It's that time of the year again! The weather gets cold and it's always a comfort to gather the family and roast resistors together. Throw in some electrolytics if you like the sound of popcorn.
This video is really a reminder of how much fun people had exploring the possibilities of analog circuits before integrated circuits simplified every design. Nice work!😃
I went straight to op amps like the venerable 741 and hooked that up to an LM386 which, at 1 watt, is pretty loud. Since then I've moved to class-D board amps, which run on 35Vdc and are amazingly loud, run floor speakers, and are the size of a credit card. I use an old laptop power supply to run them, with a usb wifi dongle to make it work in our home theater.
Used opamp with resistor matrix DAC. even fitted both in (big) LPT port connector. Good old days.. sb-emu, LPT DAC and third-hand car speakers:) Wolfenstein never soundd so good before :) (nostalgically .. after, too)
The thing about FETs in general and power FETs in particular is that they're designed for efficient high frequency switching. Their linear region is generally considered undesirable. As such efforts are made to minimise it as much as possible instead of making it truly linear. Smaller linear region (and faster transition through it) means quicker switching, less heat output and less power wasted by the FET pretending it's a resistor. One would have to buy a special amplification FET for a project like this.
This is exactly it, and this is why you do not see common mosfets in audio use. They are designed to be switches, which oddly enough in the darlington you were using was likely designed to be. It was just not as good for what it was designed for as it had a wider linear region. That and easier interfacing is what led the world into mossets and igbjt's. I have little doubt you could look over the data sheets and find a fet with better characteristics for linear use. Also, I would be tempted to say your sine wave source is pretty dirty. If you want to play with audio there are some nice designs out there that will get that thd value down at least on order of magnitude. Of course that also beings into question the thing you are reading the thd on. Nice and able to see the harmonics and but I am not sure how many of them are caused by that scopes front end. They are great for what the do, but not optimized for very small readings. For readings around .1% or so I trust my old HP334A and a very clean source.
Thankfully today we have audio signal level standards in place so you can get away with just a single MCU with a built in ADC, PWM timer and an OpAmp combined with a MOSFET pair and 2 MOSFET driver ICs per channel. The "D class amplifier" is a nice and relatively simple project for MCU programming students, just don't forget to add a PolyFuse to the MOSFET power circuit to protect it from programming mistakes causing both transistors to open at the same time. And the best part is that you can even experiment with some DSP here starting from basic stuff like converting stereo to mono and pseudo-linear filtering up to FFT-based graphic equalizers and continue with more advanced stuff like synthetic chambers and stereo effect enhancement. The sound quality and the power you can easily get from the thing makes even quite advanced commercial analog solutions just pale in comparaison to even the simple kind of a project for electronics students. Just make sure to choose a powerful enough MCU for that, something at least with a Cortex-M4 running at lesst at 100MHz if you want to test all the modern techniques.
Collector feedback bias is even simpler, and since it has local negative feedback, should distort a bit less. The distortion of a single ended MOSFET is actually very close to that of a triode, and triode output amplifiers have been something of a holy grail for audiophools. That distortion adds a warmth that many people find more pleasing than a clean, undistorted signal.
@@pearan If you compare the static curves of a MOSFET and a typical power triode, they're almost identical, so they should have almost identical distortion, with emphasis on even harmonics. Power BJTs and IGBTs, on the other hand, have almost identical curves to power pentodes and beam "kinkless" tetrodes, so they have almost identical distortion characteristics, with emphasis on odd harmonics. I've been dabbling in home-brew guitar amps for about 15 years now and am a reformed tube amp snob. It's easy to get all the right distortion and tone shaping in all the right places at the small signal level with solid state components and then just loudify it with any clean, efficient power amplifier. No hollow state rubbish required. Small signal MOSFETS like the 2N7000 can even satisfy audiophools that want that triode "warmth."
I still use my wired headphones. Good audio quality, low price and no dead batteries to worry about in the future. Also 1 less device to charge every day.
Wired headphones all the way: They don't need to be charged, drain the phone less (at least with the phones i tested it), and best of all: No losing anything just cause they drop out of your ears. The lack of a 3.5mm jack would not be so bad if phone-manufacturers at least used USB3s features - yes, it DOES offer the option for analog audio but sadly hardly any phone supports it.
Agreed. #BringBackHeadphoneJack I had thought that the USB-C adapters were doing exactly that, until I felt the one I was borrowing and noticed it was warm.... and I immediate knew it was active, not passive! 😮💨 Granted, that was an Apple dongle, but since Samsung feels is NECESSARY to copy an evil company, I doubt my S23 Ultra does audio passthrough. I have a Fiio BTR7 and the novelty of listening to music wore off FAST and I listen to music *_so much less_* now that I can't just carry my nice headphones with me 😞 _(I also have an iBasso USB-C DAC, but even if it wasn't painfully bright, I wouldn't use it since I still need to drag that around AND it's a massive power draw)_
🔊 The speaker needs an enclosure. Simply cut a hole in a cardboard box and tack the speaker in place with hot glue or screws. You will be surprised at the difference in volume and sound quality. Great electronics explanations in these videos. 🏆
The thing about the non-linearities of the mosfet means... people will probably actually like it more. Next time try building a transformer coupled amplifier with it, you can get a massive bump in efficiency with this, and it's the topology of a vacuum tube amp which can be attractive to audio nerds. Also next time at least get a piece of cardboard or something and put the speaker in it so you don't get that thin tinny sound. Having the speaker bare like that causes pressure waves from the front and back to wrap around and cancel, reducing bass and volume.
I put together Nelson Pass's Mosfet class A Burning Amp and it is excellent. Thank you for showing the challenge with mosfets as I understand more now what I built.
What also really helps is a speaker in an enclosure that is build (I mean measured) for the speaker you are using. The second thing I wanted to give as a tip, is when using a MOSFET amp, usually there is a preamp used. But, nice project and good information!
Nice little class A amp! One thing you could have pointed out: the non-linear amplification of the Mosfet isn't always undesirable. In fact, the mosfet gain curve closely mimics the transfer curve of a vacuum tube amplifier. As the many commenters who have missed the point 😉 have said, a class A mosfet amp is very inefficient for listening to music. However, this kind of setup is loved by guitarists, who love the mellow tone of a non-linear class A amp.
A common way to approach it is to put first a pre-amp, e.g. your initial circuit, followed by a power amp circuit. The pre-amp just amplifies the voltage and focus on low noise and distortion. And the power amp adds the current (power) needed to drive the speakers. Also, low noise audio op-amps makes things simpler and modular. For example the ubiquitous NE5532, present in many audio devices for many years. Probably there is not a single piece of music in the world that has not gone through an NE5532 many times.
I've built a fair few higher power class A amps through the years. The biggest one was a stereo setup that drew 25A at 24V, requiring a lot of cooling and very big ceramic resistors. It sounded awesome though! Also a great space heater. Haha.
@@greatscottlab Hehe yeah it's a fun thing to tinker with! And the fact that everything just scales up the more power you want, it's a very simple thing to build if you have a bunch of high power components already. A vastly improved version that requires no massive resistors is the "Death of Zen" circuit form Elliott Sound Products. It's a lot more complicated and sounds just as good. So it takes away some of the simplistic charm of a big raw class A stage. Thanks for a great video as always! :D
@@H3adcrashwhat a small world solid state electronics is! Reading Elliot sound being the amplifiers built in our school trough the years make me smile (living in Argentina)
Something basic: electrolytic caps distort signals quiet a lot & in several ways at the same time. & usually unipolar ones - even if you manage to operate them only in forward direction - are even worse then the more rarer bipolar electrolytic ones. For the smaller input I'd recommend using a compact film cap, but for the output, if you're not willing to get poor from a large audio film cap, you'd really have to think outside the box to make it both safe & functional...
If you want to improve efficiency, you need to start looking at Class A/B. Class A amplifier are not really scalable. Class A/B are easy enough to do with discrete components, but if you want there is "chipamp" solution that are efficient (50-70%) and has a good audio quality. I did a stereo amp using a LM4766 and it was surprisingly good. Overall a nice analog project to do for fun.
Well, if you try hard enough, class A can be scalable. I have a friend who built 2x30W pure class A amp that draws 600W from mains while doing nothing. Ideal winter solution, room heater with crystal sound quality.
@@__MINT_ I would hardly call that "scalable" ahah. 10% effiency it's insane. Imagine that at a rock concert, you would need to put the amp outside lol.
I spent alot of time messing around with class A mosfet amps, they can be made to sound very good. but they are also so precarious, dont expect to be actually using your volume knob. but it was a good primer for when I started playing with tubes, which are far more forgiving, just because they have alot more voltage to play with. if you do need a small, simple power amp, you simply cant go past power opamps like the LM1875 or LM3886 (other brands are available). for how few parts required , the ease of construction and fidelity is incredible. you are going to want a very stout power supply, lots of filter caps and a big bit of iron. and significant amounts of cooling. If you want a bargain price DIY audiophile setup, a moderately good USB DAC, and adjustable active crossover, a LM1875 to run your tweeters and an LM3886 on your woofers, in an MDF speaker box will blow your socks off. all for less than the price of an 'audiophool grade' power cable.
There are some people that can’t hear distortion…. Speakers that turn good music into something that triggers my chalkboard response and others are just turning it up even more and enjoying being oblivious.
When I was 14 years old, I made an amplifier with this exact same mosfet but used a single resistor. I don't know how it works but I still remember the circuit. I added a 1k resistor between the gate and drain of MOSFET and connected the drain to the -ve terminal of a speaker, +ve terminal to a 5V supply, Source of MOSFET to the 0v rail and connected the audio into the Drain of the MOSFET. It works like magic.
Hey, I remember that headphones amplifier! I love the way you revisited that. I believe the most efficient and generally good design would be an opamp-like structure, with a feedback. You could also build a class D amp of course, but that's quite a bit trickier and not as "pure analog" That being said, I am myself looking to build an amplifier for a headset that would need a decent amount of power. It's a DT880, and it sounds pretty bad, also without bass, when plugged directly into a phone. An EQ doesn't solve it, it really feels like a lack of power. I'm not sure what would be a good amp design that won't hiss. I thought of several NE5532 mounted in parallel...
Me hearing and enjoying whole video through my diy audio class A amp, with one resistor (1ohm) and very good linear mosfet, and bias current set 7 amps with vcc 14.4v. Both are same idle current for left and right audio channels, suitable for headphones and very large floor speakers.
Hi! I am new to electronics and i made a little amplifier some time ago. It was really simple. Idk much about amplifier classes and things like this but it was easy to make and had 3 components. 1 mosfet, 1 capacitor and a resistor. It sounded good(maybe because i was excited that i made it myself), there are youtube videos on it, i would like to see a short video on it.Keep it up with these amazing videos!
Ah... I remember it took me a while, but I built my first transistor circuits from book "Dators Fizikas Laboratorijā Skolā". A Relay controlled trough LPT port by a DOS program in Pascal used a signal transistor BK315 and medium power transistor, I think 817 (russian numbers, something like BC517-ish and BD40), and audio amplifier circuit using one trasistor. I was strugling to get my head wrapped around it for a while - as 4 resistors to set up currents affect each other... Good memories.
EDIT: it looked like the THD on the mosfet was happening at around -75db to -95db (circa) which is not really an issue in a small speaker like this and can be further mitigated with a good enclosure to the point of becoming insignificant. original comment: man, this is such a cool and practical project to draw in noobs like myself. I think I've been subbed since 2017-ish and this is the first project I'm going to attempt. I'm not sure what that says about your turnover rate, but I'm super thankful at least ;) ps. please consider doing a simple preamp some day
making a class-D ampliier next would be cool, to show efficiency increases. also perhaps using one of those super cheap 3w class-d amplifiers, and making a class-d amplifier amplifier. essentially a H-bridge driver connected to the outputs of the class-D amplifier to increase the voltage and amps on the output. since these days almost everyone uses class-D amplifiers as they are much louder and more efficient, and often much cheaper as well if you want okay quality. completely making your own class-D amplifier also would be cool, even though I know there are many simple ways like using a comparator and such, it would be interesting to see a as simple and cheap as possible way to make a okay class-d amplifier. even better if possible with only normal parts so without parts people would need to custom order(only things a average hobbyist would have). ofcource just for fun since a class-D amplifier doesn't need to be that high power. and can easily become dangerously powerfull like when for example using the €0.50(new original) IRL7833 mosfet you can technically send 18000W pulses (30V and 300A(pulsed)(150A constant and only 3.8mOhm RDS on max (so 0.0038Ohm)). www.infineon.com/dgdl/irl7833pbf.pdf?fileId=5546d462533600a4015356600d71257b essentially weak 1W and 3W class-D amplifiers are super cheap, and up to around 120W they are not that expensive either. however even at something like 50W the price increase probably already is way more than when using a super cheap class-D amplifier and combining it with a self made H-Bridge cirquit to amplify it(self made since that is much cheaper than prebought ones often, even though for lower power you can use one of the cheap ic's for that. but most cheap h-bridges have capacitors build in which doesn't need to be bad and can improve performance, but a class-d amplifier works at much higher frequencies than a dc motor drivers and most cheap H-bridge cirquits are made for driving dc motors so with a big capacitor(low pass filter).
Yes, the problem with Class A amplifiers: efficiency of less than 50%, if you're luck. Class B will be really efficient, but sound like you are listening underwater with how badly they distort things. Class C are pretty efficient and sound alright, but are not really suitable for music level fidelity. They are fine for a telephone conversation or an intercom. A lot of cheap amplifiers are Class C. What you are going to land on is a Class D amplifier as your perfect solution, which is a digital amplifier. It uses a high frequency pulse modulated signal to form the sinusoidal sound waves by controlling the number of pulses used per second in any given time frame. This allows any waveform below a certain frequency of the driver frequency to be recreated. This is highly power efficient, very accurate, and uses MOSFETs to drive the power side of the circuit. For small, sub 1 watt applications, you can get single chip amps that just require a heat sink or some copper/soldier on the board to dissipate some of the heat they will generate. Most surround sound systems use Class D amps, as does your phone, and your computer.
Note that MOSFETs usually have a positive temperature feedback when operating in its linear region. This means with the same gate voltage, it gets a lower Rdson with a higher temperature. This means it gets into a sort of slow thermal runaway. There are MOSFETs though that feature a negative feedback if I'm right. This is one of the reasons I'll always try to avoid MOSFETs in linear applications. That being said, I love to see you make an LDO using a MOSFET and a zener diode. If you connect the gate of a MOSFET to a stable voltage made with a zener diode, you get a crude LDO. It drops its drain at its GS threshold voltage. I want to use them for very low power applications but I've never done it.
I made similar mosfet amplifier 10 years back, I had to adjust the potentiometer every few days due to distortion. Not sure if it was due to change in mosfet characteristics or drift in potentiometer. I still dont have tool like you to check, so used my ears to figure out the distortion.
Another problem with high power MOSFETs is that they were designed as switches. In other words they try to design them to go from "off" to "on" in a narrow range. By modifying the gate design and the geometry of the source and drain the turn on voltage doesn't operate as a linear input. It's what allows a power MOSFET to quickly turn on and off at high frequencies without a long transition period. I've used a tungsten lamp (like a car headlamp) for the collector or drain resistor. It has a non linear resistance and sort of acts like a current source, plus it was designed to get hot. You can get them for free if you check out a car repair shop. Most cars have a dual filament, so if the low beam goes bad the high filament still works.
FBSOA coul tell something is mosfet suitable drive straight like voltage controller resistor. Then comes linearity curves with given different voltage values and maximum power dissipations, transconductanse with different bias voltages ect :D
I had some IHW20N135R5 in surplus that I needed to repair an induction cooktop and did an amplifier experiment with them out of boredom. I was amazed at how good the sound was. My circuit looked different from this one of yours, I put everything together freehand without doing any real calculations and I succeeded. But I think it would be even better if I calculated everything correctly, but this was just a play out of boredom 😁
Great Scott - If you're interested in audio amplifiers, I would direct you to the work of Nelson Pass and his Zen and First Watt series of amplifiers. The former are simple (but great sounding) class A DIY projects for instruction, and the latter are commercial products that he's released the schematics for. Pass himself hangs out in the DIY Audio forums, but there are lots of crazy audio/electronics enthusiasts there answering questions all the time.
Seeing that a basic amplifier need around 7W to drive that speaker to make some loud music makes me even more impressed on how well optimized these boomboxes are nowadays. I have a Harman-Kardon Onyx Studio3 and its battery died eventually. I was looking for replacements, and realised, that it works with a singe 18650 cell that is ~2400mAh meaning roughly 8Wh. That thing works for 5-6 hours straight from battery on a reasonably loud volume.
There is another catch with MOSFETS, most that you come across are designed for switching only. with higher power ones often using multiple FET in parallel internally to get the desired current, trouble is they don't all operate identically, so when biased to be linear, the load is not shared properly internally, meaning you can kill the MOSFET. In it's intended use, hard switching, they never see this linear zone, so no problems. So if you want to use a MOSFET as shown, make sure it is designed/intended for linear/audio use.
Mosfets are current amplifier devices while bjts and fets are voltage. They are also a lot more difficult to get stable when put in parallel and dealing with bigger output power. Controlling them is more expensive in practice as well.
I would like to share a simplest way to design this class A amplifier. 1) Voltage gain is closely to Rc / Re. 2) Once the voltage gain is defined, fine tune Vb ( the value of R1 & R2 ) to get Vc closely to half of Vcc. The transistor will working at linear region for less distortion but maximum output voltage swing. 3) In parallel a capacity at Re can get higher output voltage.
I have started to build a similar with FET 2SK1058 and also a driver - a small Soviet 6S31B tube. That requires two voltages, 24V for the FET and 110V for the tube, but I got transformers.
Most audio amplifiers have capacitors to stabilize voltage spikes and multiple mosfets to increase output. The beauty is its a DC voltage controlling a variable ac sin wave
This came at a great time! I'm trying to create an affordable PEMF therapy device. It's not driving a speaker, but a high current coil to produce a magnetic field. This simple amplifier will work nicely for that!
The common emitter or common source configuration you are showing here is not really a good choice for a power amplifier. The low RDSon of the MOSFET is not at all utilized in this configuration since the current to the speaker is not actually passing through the transistor. That's unless you also make the drain resistor quite small, which would result in an unreasonably high quiescent current. But it's nice to see that you could make it working at all...
A follower like it's usually done would have been more useful for driving loads, and can still be technically called an amplifier (of current). Or maybe just lots of feedback to have a low output impedance
Nice circuit & walk through. I always learn something interesting from watching your videos. Maybe ask HexiBase to 3D print you an exclosure for that little speaker…?
Maybe you could make a Video on how to amplify Audio signals created by a Mikocontroller, either with a smart circuit a a amplifier like the LM4991, since I'm not smart enough to figure it out and could use some help.
Don't forget - P=IV. If you dissipate too.much power through these resistors you'll just cook them. Reliably. If you don't have higher power resistors, you can run a bunch in parallel. That way you can also fine-tune the final value. It's messy, but it works.
You probably want to drive your Darlington with a preamp that acts as a voltage regulator for your Darlington or even Mosfet amp so it's not at constant power all the time, but draws power depending on the input volume.
another problem when using a power mosfet a small (10-22 ohms) carbon composition resistor must be used to kill any stray inductance from being coupled to the gate, if not parasitic oscillations (from 250 MHZ to 1GHZ) could be present on the output, I learned this from a Siliconix power mosfet handbook
I'm not an audio guy, but I know Mosfets are very much suited for class-D amplifiers. With a good LC output filter, it can't be beat. Both in efficiency and sound quality. I guess that's why they're the most popular. Some chips are so efficient, they require no heat-sinks.
I appreciate the process, but I also love the little simple amps with BT that you can find of aliexpress for like $3. There are ones that can handle decent power for like $20
Mosfets are most commonly used in Class D amplifiers. In this case they are fully on or off to drive the max power to the speakers. Class D is significantly more complex than Class A however. But any decent audio amplifier on the market is typically a Class D with mosfets on a large heat sink.
I use an IEM so honestly I need a high quality DAC AMP with little or no noise but I might use this to make an electric motor speaker and turn it into a nicely impressive circuit and put it on wood or something else.
surely you could make a much better performing amp by using a single or maybe a few nice opamp chips? or even if you used a few more caps to make sure power going into the mosfet / transistors are nice and clean i think you would get better THD levels
Class A amplifiers are fine, but if you want something more functional, you have to go to dedicated integrated circuits. Something like NJM2073 for instance (at least if you want it to be in a small package and working with low supply voltage).
Hi great scott. I was using a drill with a 21v battery pack. And sometimes at work. Outlet is not always available since I work as a windows installer here in the philippines. And I wanted to request if you will notice me if you can create a circuit that can charge both 12.6v and a 21v drill battery. With an 18v 30w solar input. Thanks a lot!
5:36 0.5 A current over 12ohm Rc and 2.4ohm Re, they need to be 3Watt and 0.6Watt resistors. Of course the poor 1/8 or 1/4 W resistors will go out with a puff hombre. 12:43 the issue with fets is even harmonics dominate which distorts the timbre directly, whereas odd harmonics are preferred, look at vacuum tube amps .
What do you think about using 2 copies of that MOSFET class A in a bridge configuration in order to gain more power? Just connect the input of the second copy to the ground, and the outputs of both to the both ends of the speaker terminals. One amp can deliver up to 6 watts (12V * 0.5A) or is it less? Not sure how to calculate the bridge configuration, or if it’s even possible in this case?
Class D would be great compact and efficient with pd trigger board we can get high voltage from mobile charger and get a high watt output at the speakers.
Class D aren't really easy to grasp though. Not so good for a video. I would go from class A, to class AB, then filtering and FFT basics, PWM and then Class D. Maybe even some sampling theory.
I've always felt like this is one of the biggest issues when designing any electronic circuit that handles higher power. Yes it can be cooled down and yes the circuit will probably work but the fact that it gets hot means it is wasting a lot of power and ultimately indicates a bad design and I personally feel like any self-respecting electronics engineer should cringe at the idea of just going with the simple yet inefficient way of designing anything. Damn I've been needing to say that for a long time. Anyways I'm really excited about the next audio project you mentioned and I can't wait to see what solution you use to solve the inefficiency issue. Though I just realised "home audio project" doesn't necessarily sound like building the speaker amplifiers from the ground up but I'm still really curious about what you have cooking. Great video as always!
5:28 Why 10% of 12V? Could you explain please, or point me to resources. My way would have been to look at the Vce to Ic Chart, look for the 500mA and find out the Vce. Then Re= 6V-Vce/500mA.
how about the Amplifier that use 2 Transistors (PNP+NPN) together as i see in the Chinese Amplifiers they sound pretty good and loud I'm not sure how 2 transistors work together for single speaker, but it does carry very high power to the speaker these premade Amplifiers hard to fix but if there was simpler way to understand how they work i might be able to fix them
Please build a class ab amplifier using only n channel mosfets, with a single sided power supply, as most class ab amp and irs2092s based class d amps are usually on symmetrical power supply
I think voltage gain by bipolar followed by MOSFETs in push-pull and using feedback should do a nice job. The feedback can be used to tame the non-linearities.
I appreciate the way you revisit your past projects as it helps those with less experience 'like myself' to improve by learning.
My pleasure! And also I had to revisit it for a future home audio project of mine ;-)
@@greatscottlab Ah yes! Now that is just a part of the lesson. Thank you.
@@greatscottlabterrible DC OFFSET thing.
It's that time of the year again! The weather gets cold and it's always a comfort to gather the family and roast resistors together. Throw in some electrolytics if you like the sound of popcorn.
This video is really a reminder of how much fun people had exploring the possibilities of analog circuits before integrated circuits simplified every design. Nice work!😃
I went straight to op amps like the venerable 741 and hooked that up to an LM386 which, at 1 watt, is pretty loud. Since then I've moved to class-D board amps, which run on 35Vdc and are amazingly loud, run floor speakers, and are the size of a credit card. I use an old laptop power supply to run them, with a usb wifi dongle to make it work in our home theater.
Thanks for the feedback :-) Sounds like a fun journey ;-)
Used opamp with resistor matrix DAC. even fitted both in (big) LPT port connector. Good old days.. sb-emu, LPT DAC and third-hand car speakers:)
Wolfenstein never soundd so good before :)
(nostalgically .. after, too)
@@matikaevur6299 cool =)
My friend has a class-D amp, this thing sounds great, is really powerful and, as you said, tiny
@@greatscottlab Of those who dwell on this Earth, yes, I was here first.
The thing about FETs in general and power FETs in particular is that they're designed for efficient high frequency switching. Their linear region is generally considered undesirable. As such efforts are made to minimise it as much as possible instead of making it truly linear. Smaller linear region (and faster transition through it) means quicker switching, less heat output and less power wasted by the FET pretending it's a resistor.
One would have to buy a special amplification FET for a project like this.
This is exactly it, and this is why you do not see common mosfets in audio use. They are designed to be switches, which oddly enough in the darlington you were using was likely designed to be. It was just not as good for what it was designed for as it had a wider linear region. That and easier interfacing is what led the world into mossets and igbjt's. I have little doubt you could look over the data sheets and find a fet with better characteristics for linear use. Also, I would be tempted to say your sine wave source is pretty dirty. If you want to play with audio there are some nice designs out there that will get that thd value down at least on order of magnitude. Of course that also beings into question the thing you are reading the thd on. Nice and able to see the harmonics and but I am not sure how many of them are caused by that scopes front end. They are great for what the do, but not optimized for very small readings. For readings around .1% or so I trust my old HP334A and a very clean source.
Thankfully today we have audio signal level standards in place so you can get away with just a single MCU with a built in ADC, PWM timer and an OpAmp combined with a MOSFET pair and 2 MOSFET driver ICs per channel. The "D class amplifier" is a nice and relatively simple project for MCU programming students, just don't forget to add a PolyFuse to the MOSFET power circuit to protect it from programming mistakes causing both transistors to open at the same time. And the best part is that you can even experiment with some DSP here starting from basic stuff like converting stereo to mono and pseudo-linear filtering up to FFT-based graphic equalizers and continue with more advanced stuff like synthetic chambers and stereo effect enhancement. The sound quality and the power you can easily get from the thing makes even quite advanced commercial analog solutions just pale in comparaison to even the simple kind of a project for electronics students. Just make sure to choose a powerful enough MCU for that, something at least with a Cortex-M4 running at lesst at 100MHz if you want to test all the modern techniques.
add a USB C DAC in the future amp project, so you can just use 1 cable to the phone/laptop to provide both small power and audio signal
Will do ;-)
Collector feedback bias is even simpler, and since it has local negative feedback, should distort a bit less.
The distortion of a single ended MOSFET is actually very close to that of a triode, and triode output amplifiers have been something of a holy grail for audiophools. That distortion adds a warmth that many people find more pleasing than a clean, undistorted signal.
Thats why audiophool amplifiers still uses vacum tube which has even more distortion
@@pearan If you compare the static curves of a MOSFET and a typical power triode, they're almost identical, so they should have almost identical distortion, with emphasis on even harmonics.
Power BJTs and IGBTs, on the other hand, have almost identical curves to power pentodes and beam "kinkless" tetrodes, so they have almost identical distortion characteristics, with emphasis on odd harmonics.
I've been dabbling in home-brew guitar amps for about 15 years now and am a reformed tube amp snob. It's easy to get all the right distortion and tone shaping in all the right places at the small signal level with solid state components and then just loudify it with any clean, efficient power amplifier. No hollow state rubbish required. Small signal MOSFETS like the 2N7000 can even satisfy audiophools that want that triode "warmth."
I still use my wired headphones. Good audio quality, low price and no dead batteries to worry about in the future. Also 1 less device to charge every day.
Wired headphones all the way: They don't need to be charged, drain the phone less (at least with the phones i tested it), and best of all: No losing anything just cause they drop out of your ears.
The lack of a 3.5mm jack would not be so bad if phone-manufacturers at least used USB3s features - yes, it DOES offer the option for analog audio but sadly hardly any phone supports it.
Agreed. #BringBackHeadphoneJack
I had thought that the USB-C adapters were doing exactly that, until I felt the one I was borrowing and noticed it was warm.... and I immediate knew it was active, not passive! 😮💨
Granted, that was an Apple dongle, but since Samsung feels is NECESSARY to copy an evil company, I doubt my S23 Ultra does audio passthrough.
I have a Fiio BTR7 and the novelty of listening to music wore off FAST and I listen to music *_so much less_* now that I can't just carry my nice headphones with me 😞
_(I also have an iBasso USB-C DAC, but even if it wasn't painfully bright, I wouldn't use it since I still need to drag that around AND it's a massive power draw)_
🔊 The speaker needs an enclosure. Simply cut a hole in a cardboard box and tack the speaker in place with hot glue or screws. You will be surprised at the difference in volume and sound quality.
Great electronics explanations in these videos. 🏆
The small bjt amp can be used as a 'pre' amp stage to drive a bigger an more efficiently desinged output stage
The thing about the non-linearities of the mosfet means... people will probably actually like it more. Next time try building a transformer coupled amplifier with it, you can get a massive bump in efficiency with this, and it's the topology of a vacuum tube amp which can be attractive to audio nerds. Also next time at least get a piece of cardboard or something and put the speaker in it so you don't get that thin tinny sound. Having the speaker bare like that causes pressure waves from the front and back to wrap around and cancel, reducing bass and volume.
I put together Nelson Pass's Mosfet class A Burning Amp and it is excellent. Thank you for showing the challenge with mosfets as I understand more now what I built.
What also really helps is a speaker in an enclosure that is build (I mean measured) for the speaker you are using. The second thing I wanted to give as a tip, is when using a MOSFET amp, usually there is a preamp used. But, nice project and good information!
Nice little class A amp! One thing you could have pointed out: the non-linear amplification of the Mosfet isn't always undesirable. In fact, the mosfet gain curve closely mimics the transfer curve of a vacuum tube amplifier. As the many commenters who have missed the point 😉 have said, a class A mosfet amp is very inefficient for listening to music. However, this kind of setup is loved by guitarists, who love the mellow tone of a non-linear class A amp.
yes brooooo
A common way to approach it is to put first a pre-amp, e.g. your initial circuit, followed by a power amp circuit. The pre-amp just amplifies the voltage and focus on low noise and distortion. And the power amp adds the current (power) needed to drive the speakers. Also, low noise audio op-amps makes things simpler and modular. For example the ubiquitous NE5532, present in many audio devices for many years. Probably there is not a single piece of music in the world that has not gone through an NE5532 many times.
I've built a fair few higher power class A amps through the years. The biggest one was a stereo setup that drew 25A at 24V, requiring a lot of cooling and very big ceramic resistors. It sounded awesome though! Also a great space heater. Haha.
Haha sounds like fun :-) Thanks for the feedback ;-)
@@greatscottlab Hehe yeah it's a fun thing to tinker with! And the fact that everything just scales up the more power you want, it's a very simple thing to build if you have a bunch of high power components already. A vastly improved version that requires no massive resistors is the "Death of Zen" circuit form Elliott Sound Products. It's a lot more complicated and sounds just as good. So it takes away some of the simplistic charm of a big raw class A stage.
Thanks for a great video as always!
:D
@@H3adcrashwhat a small world solid state electronics is! Reading Elliot sound being the amplifiers built in our school trough the years make me smile (living in Argentina)
Something basic: electrolytic caps distort signals quiet a lot & in several ways at the same time. & usually unipolar ones - even if you manage to operate them only in forward direction - are even worse then the more rarer bipolar electrolytic ones. For the smaller input I'd recommend using a compact film cap, but for the output, if you're not willing to get poor from a large audio film cap, you'd really have to think outside the box to make it both safe & functional...
If you want to improve efficiency, you need to start looking at Class A/B. Class A amplifier are not really scalable. Class A/B are easy enough to do with discrete components, but if you want there is "chipamp" solution that are efficient (50-70%) and has a good audio quality. I did a stereo amp using a LM4766 and it was surprisingly good. Overall a nice analog project to do for fun.
Well, if you try hard enough, class A can be scalable. I have a friend who built 2x30W pure class A amp that draws 600W from mains while doing nothing. Ideal winter solution, room heater with crystal sound quality.
@@__MINT_ I would hardly call that "scalable" ahah. 10% effiency it's insane. Imagine that at a rock concert, you would need to put the amp outside lol.
I spent alot of time messing around with class A mosfet amps, they can be made to sound very good. but they are also so precarious, dont expect to be actually using your volume knob. but it was a good primer for when I started playing with tubes, which are far more forgiving, just because they have alot more voltage to play with. if you do need a small, simple power amp, you simply cant go past power opamps like the LM1875 or LM3886 (other brands are available). for how few parts required , the ease of construction and fidelity is incredible. you are going to want a very stout power supply, lots of filter caps and a big bit of iron. and significant amounts of cooling. If you want a bargain price DIY audiophile setup, a moderately good USB DAC, and adjustable active crossover, a LM1875 to run your tweeters and an LM3886 on your woofers, in an MDF speaker box will blow your socks off. all for less than the price of an 'audiophool grade' power cable.
Had a 3 watt 4 transistor 9 volt push pull transformer coupled amp when i was a kid .loved that little toy amp and it was a good sounder
At 6.27 you should have decoupled the emitter with an electrolyte capacitor as without it you get very reduced volume.
I love the intro music and animation on this channel. Something about it invokes, for me, nostalgia for US 1980s public access television.
There are some people that can’t hear distortion…. Speakers that turn good music into something that triggers my chalkboard response and others are just turning it up even more and enjoying being oblivious.
I have made these kinds of amplifiers quite a few times but thanks to you now I understand how they work quite clearly 😊
Glad to hear that! Cheers :-)
When I was 14 years old, I made an amplifier with this exact same mosfet but used a single resistor. I don't know how it works but I still remember the circuit. I added a 1k resistor between the gate and drain of MOSFET and connected the drain to the -ve terminal of a speaker, +ve terminal to a 5V supply, Source of MOSFET to the 0v rail and connected the audio into the Drain of the MOSFET. It works like magic.
@@maheen- yes it works :)
Hey, I remember that headphones amplifier! I love the way you revisited that.
I believe the most efficient and generally good design would be an opamp-like structure, with a feedback.
You could also build a class D amp of course, but that's quite a bit trickier and not as "pure analog"
That being said, I am myself looking to build an amplifier for a headset that would need a decent amount of power. It's a DT880, and it sounds pretty bad, also without bass, when plugged directly into a phone. An EQ doesn't solve it, it really feels like a lack of power.
I'm not sure what would be a good amp design that won't hiss. I thought of several NE5532 mounted in parallel...
Me hearing and enjoying whole video through my diy audio class A amp, with one resistor (1ohm) and very good linear mosfet, and bias current set 7 amps with vcc 14.4v. Both are same idle current for left and right audio channels, suitable for headphones and very large floor speakers.
Hi! I am new to electronics and i made a little amplifier some time ago. It was really simple. Idk much about amplifier classes and things like this but it was easy to make and had 3 components. 1 mosfet, 1 capacitor and a resistor. It sounded good(maybe because i was excited that i made it myself), there are youtube videos on it, i would like to see a short video on it.Keep it up with these amazing videos!
Congratulations on 2 million Subscribers !!! :)
Ah... I remember it took me a while, but I built my first transistor circuits from book "Dators Fizikas Laboratorijā Skolā". A Relay controlled trough LPT port by a DOS program in Pascal used a signal transistor BK315 and medium power transistor, I think 817 (russian numbers, something like BC517-ish and BD40), and audio amplifier circuit using one trasistor. I was strugling to get my head wrapped around it for a while - as 4 resistors to set up currents affect each other... Good memories.
EDIT: it looked like the THD on the mosfet was happening at around -75db to -95db (circa) which is not really an issue in a small speaker like this and can be further mitigated with a good enclosure to the point of becoming insignificant.
original comment: man, this is such a cool and practical project to draw in noobs like myself. I think I've been subbed since 2017-ish and this is the first project I'm going to attempt. I'm not sure what that says about your turnover rate, but I'm super thankful at least ;)
ps. please consider doing a simple preamp some day
making a class-D ampliier next would be cool, to show efficiency increases.
also perhaps using one of those super cheap 3w class-d amplifiers, and making a class-d amplifier amplifier.
essentially a H-bridge driver connected to the outputs of the class-D amplifier to increase the voltage and amps on the output.
since these days almost everyone uses class-D amplifiers as they are much louder and more efficient, and often much cheaper as well if you want okay quality.
completely making your own class-D amplifier also would be cool, even though I know there are many simple ways like using a comparator and such, it would be interesting to see a as simple and cheap as possible way to make a okay class-d amplifier.
even better if possible with only normal parts so without parts people would need to custom order(only things a average hobbyist would have).
ofcource just for fun since a class-D amplifier doesn't need to be that high power. and can easily become dangerously powerfull like when for example using the €0.50(new original) IRL7833 mosfet you can technically send 18000W pulses (30V and 300A(pulsed)(150A constant and only 3.8mOhm RDS on max (so 0.0038Ohm)).
www.infineon.com/dgdl/irl7833pbf.pdf?fileId=5546d462533600a4015356600d71257b
essentially weak 1W and 3W class-D amplifiers are super cheap, and up to around 120W they are not that expensive either.
however even at something like 50W the price increase probably already is way more than when using a super cheap class-D amplifier and combining it with a self made H-Bridge cirquit to amplify it(self made since that is much cheaper than prebought ones often, even though for lower power you can use one of the cheap ic's for that.
but most cheap h-bridges have capacitors build in which doesn't need to be bad and can improve performance, but a class-d amplifier works at much higher frequencies than a dc motor drivers and most cheap H-bridge cirquits are made for driving dc motors so with a big capacitor(low pass filter).
Yes, the problem with Class A amplifiers: efficiency of less than 50%, if you're luck. Class B will be really efficient, but sound like you are listening underwater with how badly they distort things. Class C are pretty efficient and sound alright, but are not really suitable for music level fidelity. They are fine for a telephone conversation or an intercom. A lot of cheap amplifiers are Class C.
What you are going to land on is a Class D amplifier as your perfect solution, which is a digital amplifier. It uses a high frequency pulse modulated signal to form the sinusoidal sound waves by controlling the number of pulses used per second in any given time frame. This allows any waveform below a certain frequency of the driver frequency to be recreated. This is highly power efficient, very accurate, and uses MOSFETs to drive the power side of the circuit. For small, sub 1 watt applications, you can get single chip amps that just require a heat sink or some copper/soldier on the board to dissipate some of the heat they will generate. Most surround sound systems use Class D amps, as does your phone, and your computer.
Note that MOSFETs usually have a positive temperature feedback when operating in its linear region. This means with the same gate voltage, it gets a lower Rdson with a higher temperature. This means it gets into a sort of slow thermal runaway. There are MOSFETs though that feature a negative feedback if I'm right. This is one of the reasons I'll always try to avoid MOSFETs in linear applications.
That being said, I love to see you make an LDO using a MOSFET and a zener diode. If you connect the gate of a MOSFET to a stable voltage made with a zener diode, you get a crude LDO. It drops its drain at its GS threshold voltage. I want to use them for very low power applications but I've never done it.
I made similar mosfet amplifier 10 years back, I had to adjust the potentiometer every few days due to distortion. Not sure if it was due to change in mosfet characteristics or drift in potentiometer. I still dont have tool like you to check, so used my ears to figure out the distortion.
When will we see a IGBT opamp design
Another problem with high power MOSFETs is that they were designed as switches. In other words they try to design them to go from "off" to "on" in a narrow range. By modifying the gate design and the geometry of the source and drain the turn on voltage doesn't operate as a linear input. It's what allows a power MOSFET to quickly turn on and off at high frequencies without a long transition period.
I've used a tungsten lamp (like a car headlamp) for the collector or drain resistor. It has a non linear resistance and sort of acts like a current source, plus it was designed to get hot. You can get them for free if you check out a car repair shop. Most cars have a dual filament, so if the low beam goes bad the high filament still works.
FBSOA coul tell something is mosfet suitable drive straight like voltage controller resistor. Then comes linearity curves with given different voltage values and maximum power dissipations, transconductanse with different bias voltages ect :D
I had some IHW20N135R5 in surplus that I needed to repair an induction cooktop and did an amplifier experiment with them out of boredom. I was amazed at how good the sound was. My circuit looked different from this one of yours, I put everything together freehand without doing any real calculations and I succeeded. But I think it would be even better if I calculated everything correctly, but this was just a play out of boredom 😁
Great Scott - If you're interested in audio amplifiers, I would direct you to the work of Nelson Pass and his Zen and First Watt series of amplifiers. The former are simple (but great sounding) class A DIY projects for instruction, and the latter are commercial products that he's released the schematics for. Pass himself hangs out in the DIY Audio forums, but there are lots of crazy audio/electronics enthusiasts there answering questions all the time.
Seeing that a basic amplifier need around 7W to drive that speaker to make some loud music makes me even more impressed on how well optimized these boomboxes are nowadays.
I have a Harman-Kardon Onyx Studio3 and its battery died eventually. I was looking for replacements, and realised, that it works with a singe 18650 cell that is ~2400mAh meaning roughly 8Wh. That thing works for 5-6 hours straight from battery on a reasonably loud volume.
There is another catch with MOSFETS, most that you come across are designed for switching only. with higher power ones often using multiple FET in parallel internally to get the desired current, trouble is they don't all operate identically, so when biased to be linear, the load is not shared properly internally, meaning you can kill the MOSFET. In it's intended use, hard switching, they never see this linear zone, so no problems.
So if you want to use a MOSFET as shown, make sure it is designed/intended for linear/audio use.
Mosfets are current amplifier devices while bjts and fets are voltage. They are also a lot more difficult to get stable when put in parallel and dealing with bigger output power. Controlling them is more expensive in practice as well.
I would like to share a simplest way to design this class A amplifier. 1) Voltage gain is closely to Rc / Re. 2) Once the voltage gain is defined, fine tune Vb ( the value of R1 & R2 ) to get Vc closely to half of Vcc. The transistor will working at linear region for less distortion but maximum output voltage swing. 3) In parallel a capacity at Re can get higher output voltage.
I have started to build a similar with FET 2SK1058 and also a driver - a small Soviet 6S31B tube. That requires two voltages, 24V for the FET and 110V for the tube, but I got transformers.
Most audio amplifiers have capacitors to stabilize voltage spikes and multiple mosfets to increase output. The beauty is its a DC voltage controlling a variable ac sin wave
This came at a great time! I'm trying to create an affordable PEMF therapy device. It's not driving a speaker, but a high current coil to produce a magnetic field.
This simple amplifier will work nicely for that!
The common emitter or common source configuration you are showing here is not really a good choice for a power amplifier. The low RDSon of the MOSFET is not at all utilized in this configuration since the current to the speaker is not actually passing through the transistor. That's unless you also make the drain resistor quite small, which would result in an unreasonably high quiescent current.
But it's nice to see that you could make it working at all...
Thanks......I guess.
A follower like it's usually done would have been more useful for driving loads, and can still be technically called an amplifier (of current). Or maybe just lots of feedback to have a low output impedance
@@bentfishbowl3945hey! How would that be set up?
you deserve more scott ♥️
Nice circuit & walk through. I always learn something interesting from watching your videos. Maybe ask HexiBase to 3D print you an exclosure for that little speaker…?
Well Mosfet boost shematic are all around the net...
You can also think about using one FET buffer at the output...
So when we getting the vid on the nrf54l15? You know I'm dieing for it big bro. You teasing us or what!?!?!?!?!?
You can put a large capacitor across R4, the resistor from emitter to ground, to increase AC gain of the circuit. Give it a go!
Maybe you could make a Video on how to amplify Audio signals created by a Mikocontroller, either with a smart circuit a a amplifier like the LM4991, since I'm not smart enough to figure it out and could use some help.
Don't forget - P=IV. If you dissipate too.much power through these resistors you'll just cook them. Reliably.
If you don't have higher power resistors, you can run a bunch in parallel. That way you can also fine-tune the final value. It's messy, but it works.
After 0:26 I would expect a wireless solution, like BT. Great explanations as always, thanks
You probably want to drive your Darlington with a preamp that acts as a voltage regulator for your Darlington or even Mosfet amp so it's not at constant power all the time, but draws power depending on the input volume.
My electronics mentors.
Big ups great scott, 🎉
Much appreciated
Going to put an opamp in the mix somewhere to control the amplification at some point?
8:00 true linear mosfets are super rare this days. Almost all are optimized for switching applications
The gain can be improved by adding emittor bypass cap, or at least that's how you do it in preamplifiers.
another problem when using a power mosfet a small (10-22 ohms) carbon composition resistor must be used to kill any stray inductance from being coupled to the gate, if not parasitic oscillations (from 250 MHZ to 1GHZ) could be present on the output, I learned this from a Siliconix power mosfet handbook
I'm not an audio guy, but I know Mosfets are very much suited for class-D amplifiers.
With a good LC output filter, it can't be beat. Both in efficiency and sound quality.
I guess that's why they're the most popular. Some chips are so efficient, they require no heat-sinks.
can you make more videos abot where to salvage and what to salvage for spare parts please?
and also imna give a challenge: make an oscilloscope
I can put it on my to do list :-)
@@greatscottlab OH THANKS
This was a nice little project! I remember studying and building CE amplifiers like that in school
Glad you liked it!
That looks awesome. How would this be viable in a larger scale? Fx running a 100w subwoofer?
Why aren't you using a bypass capacitor across the emitter resistor to ground? Should increase the AC signal gain.
Very good video 😀 , it would be cool to have a similar video for class B, AB and D amps. Or even class C because we don't see enough of them.
Fascinating stuff, dude! Thanks a bunch for the lesson! 😃
Stay safe there with your family! 🖖😊
Thanks :-) You too
Need more projects like this on audio amplifiers to make the best amplifiers . finally a very good and useful project !
I appreciate the process, but I also love the little simple amps with BT that you can find of aliexpress for like $3. There are ones that can handle decent power for like $20
Mosfets are most commonly used in Class D amplifiers. In this case they are fully on or off to drive the max power to the speakers. Class D is significantly more complex than Class A however. But any decent audio amplifier on the market is typically a Class D with mosfets on a large heat sink.
What happens if you use a bjt into a mosfet like a darlington circuit?
A simple low power amplifier like this can be made with even less components and no heatsink if you use a TDA7052 IC.
I love that you show the maths being worked out on the schematic, it really helps understanding the process
I use an IEM so honestly I need a high quality DAC AMP with little or no noise but I might use this to make an electric motor speaker and turn it into a nicely impressive circuit and put it on wood or something else.
Go for it!
@greatscottlab Thank you for the information. I will do that. Have a nice day
Keep the cool videos coming.
I need to know where you found, or how you made those sorting boxes!! been looking for something similar myself:)
surely you could make a much better performing amp by using a single or maybe a few nice opamp chips?
or even if you used a few more caps to make sure power going into the mosfet / transistors are nice and clean i think you would get better THD levels
Class A amplifiers are fine, but if you want something more functional, you have to go to dedicated integrated circuits. Something like NJM2073 for instance (at least if you want it to be in a small package and working with low supply voltage).
Hi great scott. I was using a drill with a 21v battery pack. And sometimes at work. Outlet is not always available since I work as a windows installer here in the philippines. And I wanted to request if you will notice me if you can create a circuit that can charge both 12.6v and a 21v drill battery. With an 18v 30w solar input. Thanks a lot!
5:36 0.5 A current over 12ohm Rc and 2.4ohm Re, they need to be 3Watt and 0.6Watt resistors. Of course the poor 1/8 or 1/4 W resistors will go out with a puff hombre. 12:43 the issue with fets is even harmonics dominate which distorts the timbre directly, whereas odd harmonics are preferred, look at vacuum tube amps .
A class A FET amp? Count me in!!!
What do you think about using 2 copies of that MOSFET class A in a bridge configuration in order to gain more power? Just connect the input of the second copy to the ground, and the outputs of both to the both ends of the speaker terminals. One amp can deliver up to 6 watts (12V * 0.5A) or is it less? Not sure how to calculate the bridge configuration, or if it’s even possible in this case?
The load must be part of the calculation I think. The bigger the load the less power there will be delivered.
Cool video! Consider doing a push-pull amp next!!
Class D would be great compact and efficient with pd trigger board we can get high voltage from mobile charger and get a high watt output at the speakers.
Class D aren't really easy to grasp though. Not so good for a video. I would go from class A, to class AB, then filtering and FFT basics, PWM and then Class D. Maybe even some sampling theory.
I've always felt like this is one of the biggest issues when designing any electronic circuit that handles higher power. Yes it can be cooled down and yes the circuit will probably work but the fact that it gets hot means it is wasting a lot of power and ultimately indicates a bad design and I personally feel like any self-respecting electronics engineer should cringe at the idea of just going with the simple yet inefficient way of designing anything. Damn I've been needing to say that for a long time.
Anyways I'm really excited about the next audio project you mentioned and I can't wait to see what solution you use to solve the inefficiency issue. Though I just realised "home audio project" doesn't necessarily sound like building the speaker amplifiers from the ground up but I'm still really curious about what you have cooking.
Great video as always!
Great video! You should put something together on the various uses of an op-amp.
5:28
Why 10% of 12V? Could you explain please, or point me to resources.
My way would have been to look at the Vce to Ic Chart, look for the 500mA and find out the Vce. Then Re= 6V-Vce/500mA.
Nice build Video 👍
any easy way to swap some components in a car stereo to give it a bit more grunt? bigger mosfet or capacitor ?? Ford sync 3 tin box.
Great Scott can you make a Amp with Audio Processor? Like DolBy audio processor or may be some custom DSP ?
if you want to make an amplifier maybe you can try the socl506 driver kit
Aren't MOSFETs used for transistor based distortion pedals in music?
how about the Amplifier that use 2 Transistors (PNP+NPN) together as i see in the Chinese Amplifiers they sound pretty good and loud
I'm not sure how 2 transistors work together for single speaker, but it does carry very high power to the speaker
these premade Amplifiers hard to fix but if there was simpler way to understand how they work i might be able to fix them
Nice. If you only want current amp. you can use a voltage regulator like the LM317 or eqv. and make a class A amp of it. Thanks for your great videos.
Cool, thanks
Please build a class ab amplifier using only n channel mosfets, with a single sided power supply, as most class ab amp and irs2092s based class d amps are usually on symmetrical power supply
is it not possible to use an H-bridge system with 4 mosfe 2 N channel and 2 P channel and 1 AOP to pre-amplify the signal at the gate ?
I think voltage gain by bipolar followed by MOSFETs in push-pull and using feedback should do a nice job. The feedback can be used to tame the non-linearities.
I realize designing it yourself is the fun part but it might also be fun to see a head-to-head between your final design and an AliExpress hidden gem.