Dual Rail Supply - Different Options for Negative Voltage
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- เผยแพร่เมื่อ 1 พ.ค. 2024
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🔥How to get for example +12 and -12V. Dedicated ICs, dual rail supply with center tapped transformer and much more. Learn how to get negaive voltage.
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pleace indonesia subtitle
Sir I'm your big fan. Sir can you make a radio controler transmitter and receiver for drone with lora module (SX1278/SX1276 wireless module).. it is very helpful for us.
Batteries don't give "Positive DC voltage", they're free of any kind of reference and they can be used in circuits to provide negative voltage reference
With reference to video, he needed simultaneous positive and negative supply with respect to a common ground, which a single battery surely can't provide.
@@retweaksatapathy106 in battery circuits, you define common ground, let's say you have 2S LiPo pack and decide to use the connection between 2 cells as GND. Then you have -3.7V from one cell and +3.7V from the other cell, this is exactly how it can be done and I've seen multiple portable battery powered amplifiers that do this
@@szymonjastrzebski2909 Did you notice that how i mentioned the word "single" in my comment? For some higher voltage requirement projects or some really mini projects where space is restricted and even feasible point of view multiple sources may not be possible, although multiple sources if you are using there is use of this video, since it solely focus that you might want to use a single source. Your argument isn't wrong.
@@retweaksatapathy106 I didn't notice "single", fair, although if you need low voltage negative rail in battery operated project to eg get the Op-amp V- low enough as for example rail-to-rail ones don't always have better characteristics and are more expensive, it's often beneficial to add a 2nd, small cell for negative rail. Not only it'll give cleaner results, but also will give higher efficiency, to make a space for the cell in the project one can decrease the size of the primary cell for positive rail as it won't be sustaining the negative rail anymore.
@@Bubu567 this depends greatly on the circuit, for example for opamp based circuits what matters is that V+ and V- are far enough from the signal max out as otherwise clipping will happen, changing the supply voltage won't change anything unless you change it too much and get out of working point. Most of circuits requiring negative rail aren't sensitive to exact value of negative rail voltage. And still, technically speaking that's not a virtual ground and it wouldn't be ground drifting but voltage rail drifting, if you're using for example 2S Li-ion and using the center connection for GND, then 2 linear regulators, +3.3V and -3.3V and you're golden
The most clear explanation that I've ever heard for the use cases and ways to achieve negative voltage. Awesome channel!
As always, great video!
Since the last example is capable of delivering more current using the transformer, you could take it a step further and use variable regulators with some current bypass transistors (TO-3 style) for a big current variable power supply. That would be great for the bench! Keep up the good work. These videos are appreciated.
Thank you, it is a really important topic. Keep up the good work!
most useful! thank you so much! i've been looking for a comprehensive video on negative voltage sources for so long! thank you very much, very appreciated from me! 👏💯👍
A decent basic consideration of the topic. Thank you.
Interesting video with some great examples! On thing I noticed is that in the first example, you have your polarized capacitor reversed since the gnd ref is lower voltage than the high rail so it should be flipped.
Cool , I never understood the use of negative voltage till now but after seeing your video I understood it clearly and understood how to achive it... Keep It Up ☺️
Thank you! Soldered it with different transistors. Is working.
It's exactly the subject I am working on!!
Amazing content! Thank you to share all these knowledge! I will try to assemble the buck converter on my project!
Nice simply explained video... just want to add a couple more options for higher power applications: since boost and buck converter modules handling currents of 10 to 50 amps are commonly available, if one has a useful supply voltage already (can use a boost or other supply to get this first) one can either use a boost converter to generate a voltage further above that and use the middle of the three voltages as ground (current can flow from the top to the middle happily if the middle voltage is where the boost that is generating the top is supplied from) or using a buck module, connect the power input across from +in to +out, and a negative voltage set by the output Vset pot will be generated at the common ground (this works with most buck converters and should work with all, but I have found some which don't). This can easily generate larger -ve voltages than the +ve supply, and be paired with a boost regulator to get a balanced +- for something like an IRS2092 class-D amp module.
Lately I have been doing a lot of research online about dual rail supply for my DIY function generator output, in the meantime this guy came up with the exact same thing, quite a coincidence.😅
Awesome tutorial ! Thanks!
Thank you for this informative video.
Good work!
BEAUTIFUL! I feel my 2 polarities
Great video. I would recommend an input fuse in that last center-tapped transformer example. I know that’s not the focus of your video, but a fuse is immensely important, so it is good to get people thinking about that aspect of circuit design right from the start. Also a good rule is to use an isolation transformer of some sort when working with mains voltage.
Unless doing something highly dodgy like using a tapped autotransformer (VERY dumb) any low voltage supply will automatically use an isolation transformer.
Helpful video. I liked it 👍
Just noting that it is less common (especially in audio applications) to regulate the rails of the supply. Yes the rails will sag under load, it’s just critical that your max load will not allow clipping into the rails. This headspace will ensure clean outputs. This same approach goes for both power path to speakers as well as signal attenuation. The regulation circuitry can inject noise, so less is more. Great video!
I have a question: how would you achieve the same results without regulation?
@@ehinostroza I started typing out a reply but got lengthy. I would note, I'm only referencing the end where he's transitioning discussing traditional center tap transformer supplies. Here's a great resource on the subject, specifically chapter 9. Goes into the pros and cons of regulated vs unregulated supplies for audio applications. d1.amobbs.com/bbs_upload782111/files_29/ourdev_554203.pdf
@@aaronwunderlich3070 Thanks a lot! I have a similar document called "Small Signal Audio Design" from the same author. I'm struggling on how to get the best power supply with the minimum noise and ripple, but sometimes I think that it may not be even noticeable. I'm a newbie on all this and the more I read, the more frustrated I feel about all this, sometimes is really discouraging.
Nice video! Thanks! I never try to add a charge pump to the buck converter. Amazing idea! I hope I can find some time to try it soon.
I use simple buck converter module to make negative output buck-boost circuit. Nice to try! xD
I also use modules like this one: TIM 2-0922 to make +12 and -12 from USB. ;)
Great video. Thanks
Thank you for sharing. Like this video 👍
I've built a credit card-sized dual power supply using two TPS5430 DC-DC converter chips last year, taking a single 15V power supply. For ±12V output voltage it could provide 2.5A current for the positive rail and 1.5A for the negative, while the no-load ripple is 4mVpp and 6mVpp, respectively. Not too shabby for powering a couple of op-amps considering the low current consumption, but would be a good idea to further suppress the ripple using a pair of LDOs.
Interesting video with a lot of great solutions. Another option I have recently seen used is to use two isolated DC DC converters and then creating a virtual ground between them. This gives a reasonably stable output voltage, while still allowing for multiple amps of current draw. The only downside is that the isolated DC DC converters can be kind of expensive, especially the ones with higher current ratings.
high current is always expensive, but if you need just 1 amp a synchronous buck can be used as the ground since it has a positive and negative mosfet it can handle loads negatively and positively
@@edussantoz9034 if you require higher current, use a BJT on the output of your buck, clamp the noise using filter caps.
Thank you so much
Awesome thanks 🙏🏻 🙏🏻🙏🏻🙏🏻🙏🏻
For audio with sufficiently large capacitors, the op amp to ground only has to compensate for the differential current. So only the current that results from the op amp offset voltage or DC servo compensation. The OPA 1677 Fet Op Amp (overload-proof for start) can be enough.
5:35 This push pull is far from ideal because there's a 2*0.6v dead zone. The output of the AO cannot change instantaneously so if the requirements if the virtual ground change from source to sink the transistors won't react immediately. A simple solution to improve the situation is to add a resistor between the AO and the output. For low loads (actually low differences in loads for + and - supplies) it's the AO that directly provide the current through the resistor.
Another solution is to have an AB amplifier but that's more complicated.
Thank you very much for such a grat tip :)
@@ELECTRONOOBS Concerning the value of the resistor, we can calculate its value from the fact that the maximum voltage it sees is 0.6V and the maximum current the amplifier can deliver, keeping a bit of margins because some will go in the transistors. Let's says for example 50mA, rounded down to 40mA. U=R.I gives
R=U/I=0.6/0.040=15 Ω
A standard 22 Ω should be fine.
Your videos are very instructive and helpful, but I have one doubt: Is it possible to get the same results of a center tapped transformer using a normal transformer? (without center tap) and one more question: how will the ripple be in that case?
Andrei,
Thank you for this awesome video.
The MP1484 TD2786 dual Boost link goes to a board that looks different from the one in the video. Is this the same board? I'm assuming the way this board works is you put in the rated voltage in + DC voltage and it returns both positive and negative of that voltage on the output?
✅✅✅✅✅Good job✅✅✅✅✅
Not sure if you know them but I would be really interested in the efficiency rating of those of those power supply's too.
i have a question: the 1st solution was a voltage divider right? but the amplifier opamp circuit's ground should be connected to the (0 volt) middle of dual rail isn't it? is there a way to make it to 0 volt instead of split voltage +-6 as a middle ground just like in center tap transformer?
Thanks man. Am a tutor asante sana
use a sinchronous buck converter as half the voltage from the input and use that voltage as a ground since it has a positive and negative mosfet it can handle very well with positive and negative loads
Hello Mister. I have a question that was not so clear for me on your video. The PSU created with the Transformer will for sure deliver more current. But will also have less noise them the module with 2 ICs? I need a +12V and -12V PSU ( max 1A in each rail) to power a DIY milliohmmeter. I am not sure I can use this module and have it all on a small enclosure with I could power with a 24V Battery pack or a 24V Switch mode PSU, or going with the transformer option. Will the transformer give me more accurate readings in this case? The design for the milliohmmeter I got it from Electrolab channel. I really appreciate any help. Thanks a lot!
how do you select the value for charge pump capacitor?
Curious why you didn't cover High Frequency transformers for the split. You mentioned about using the Mains to power the transformer, but what about using a bank of FETs to create high freq?
Basically a flyback converter, with split output from what I remember about that topology.
You're making a switching dual rail power supply, and that's indeed a great idea for a high power application. Just not the simplest solution so I think it would fly past the target complexity of the video.
Maybe that would be for a future video. Thanks!
Can some one tell my if they tryed that circuets on alternators as cloosed loop voltage regulation ,or useing it as starter motor voltage boosting or any ignition coil controling out put in cloosed loop circuet? I have tremendes problems with my 80s Opel I need terribli retarding circuet for my HEI ignition system basisali its to much coold in my land and my car does not support any upgrades my land also does not have option to buy 5 pin GM Ignition Module so Im cinde of stuck dono what to do? Is there any posibility to trick that deam ignition module/pick up coil or E Core Ignition coil to some how phase shift??? Also in the past I used hv ceramic capacitors to boost my ignition coil peopel call that staff plasma ignition it has some good advantages but also draw back one of problems I acured was the delco 12si alternator is constantli back feading true the bulb if I use those hv capacitors on my ignition coil the starting current wont acure unless I rew up my engine at around 3-4krpm so the bulb is constantli back feading If I dont go higher roms and the bulb refuse to shut of other vise. I know I dont have diode in my field wire but regardless I think my alternator wuld still not charge properli because I think it uses the baterry - voltage as reference point for the ic chip inside the voltage regulstor I opened up that thing to see whats inside only small ic chip and 2 capacitors nothing ells.So Im kinde of in dilema now It apears resistor/caoacitor box's can control alternators out put manuali but I dont know honestli how to counter those effects what to use value of capacitor and resistor to restore my alternator to normal values and where to place those conections exactli??? Thats the problems with ic chips I ques they are effected by static or arcing.Also similar crap happens if for some reason my xenon bulb start to shut arcs with out ballast basicali ,arcing dual relays shity gm wire harnest or stuck vibrating horn similar effects acure. So Im anoyed with this shit + the chassys start rosting more then usuali so I hoppe some one has ideas how grounding is done by cars with out useing the chassys at all what rubber to use exactli because Im interested how posibli cloosed loop system work . I also was curiuse if generators current cutt out selenoid wuld might work on alternators like the delco 12 si I hopped there is posibility to force that deam thing to charge constantli by planting a push button exitation wire after engine is started or sone thing similar. I reali hoppe some one can help my. The ic chip used for the 4 pin GM Ignition Module uses the MC 3334 design easeli found on google scematic Im preaty much shure peopel after looking at that circuet wuld agree with my its reali sloppy design doesnt work on lowr engine rpm has slow ignition coil saturation and has no variabiliti for the ignition coil what so ever so no wonder Im anoyed at that thing. So hoppe some one has similar experiances
Just bought the buck-boost type with split rail output. I hope it is not noisy unlike the first that I have which is just a boost converter with split rail output.
@@jim9930 thanks 👍
🔥🔥
Nice video. Can you provide links to that particular board?
You have links in the description for all 3 modules
Well I learnt something.
For a quick and dirty Low Power dual supply i use a max232 or eqivalent chip
You don't necessarily need a center tapped transformer... You can use any AC and just two diodes and use half of the waveform to charge one capacitor and the other half to charge another
Your choice of smokey background while talking about power electronics is giving me magic smoke anxiety.
idea for the future:
DIY USB-C microphone
like DIY Perks, but better explained
dual power can be achieved by connecting 2 adapters in series where mid point is neutral
Be careful that they're both insulated type adapters. There are some power converters out there that are not insulated (for example the buck and boost converters shown) that would instead make a short.
At 11:21 negative voltage regulator should be LM7912. (Positive part is ok)
Smps tl494... In 12v out 2x(XXXvolt) :)
What happens if you connect 2 batteries in series and you put one multimeter tip in the connection between the batteries, and with the other tip you measure the voltage in the positive and negative batteries terminals? You should get a negative and positive voltage.
you can use that but will not have a stable voltage sometimes one battery could discharge more than the other, a simple solution would be just to use one buck to stabilize the output and a synchronous buck with half the voltage and it could handle voth positive and negative loads since it has a positive and negative mosfets
@@edussantoz9034 batteries are chemically set to output a voltage, only when they start dying does their voltage sway.
What is the difference between regulators that accept positive and negative viltages ( LM 7812 and LM7912 ) ? Why can't we just place LM7812 in reverse to provide a negative rail ?
Because the regulators only work in one direction, you can't just reverse the polarity. Well, you can, but not for long 🙂
And the two regulators are doing different things when you think about it related to the GND reference coming from the center tap of the transformer. The LM 7812 steps the 15 volts down to 12. The 7912 steps the voltage up from -15 to -12 volt.
Because you change the definition of ground and if something else uses that ground you will burn it up
dc transformer - its cool)
Or you could also use a voltage devider using 2 equal value resisters.
He just explained why that was a bad idea
The timestamps does not fit at all ...
00:00 Intro
1:37 Commercial Ad
2:36 What is the goal?
2:52 Method 1: Voltage devider
3:48 Method 2: Divider + OPAMP
5:09 Method 3: Divider + OPAMP + BJTs
5:43 Method 4: Charge Pump
8:35 Method 5: Double Boost Converter
9:24 Method 6: ICL7662 ICs
10:26 Method 7: Center Tapped Transformer
Sir i want to know if it is possible to combine ( pt2262, pt2272) to 4 chnls , (rx-2b, tx-2b) to 5 chnls ,( ht12e, ht12d) to 4 chnls with 433mhz transmitter and receiver to get a 13 chnls RC device and if possible to see example of the circuits
Never used taht IC. Don't know...
Also sir please make a video every weak bcs am always wating to learn something new
lol, 3 Amps.....how about heavy duty like 18A + - 65V to power up 2 kits of 500w irs 2092S audio amplifier? (my ttoroidal transformer it's around 7kg and I want to change it with something lighter weight)
use two heavy power smps get one posititive of one and tie to the negative of the other, thats your grounf now and you will have a positive to ground that will give positive voltage and a negative to ground that will give negative.
I have another idea...its a smps with reversed dual output transformer
Sir can you make a video on all agriculture farm monitring from anywhere in the world please
why and where we need negative voltage?
Negative voltages are normally used in amplifiers
For stabilising negative supply need to use LM7912. Not LM7812
I can already see what you've fixed.
haha his voice sounds exactly like Great Scott, is this an accent?
Gold does not provide greater conductivity. It prevents corrosion. Silver is a better conductor.
Thanks sir i seen Hindi translation in display
Yes, is it good?
Why do you need an LDO rated for negative voltage for the negative rail? Couldn't you orient it so voltage is positive relative to your ground rail?
Redefining ground is a big no no.
@@cpK054L Well that tells me you conventionally wouldn't do that. But why would it be bad to do that physically/scientifically?
FULL BRIDGE RECTIFIER!!!
Also known as a bipolar power supply
🌟🌟🌷🌟🌟
PLEASE, do not use the so-called "Ground lead" when measuring an SMPS !!
the capacitance of a typical passive probe, and the inductance of that lead, give a resonance at 90-120 MHz !! Too much 'fake noise' !
Yes, you want to keep the area between the tip and ground lead as small as possible to minimise noise pick-up. I would place dedicated test points right next to the output capacitor to allow probing without probe tip caps and with grounding springs.
Hi sir I'm your big fan. Sir can you make a transmitter and receiver with lora module (SX1278/SX1276 wireless module) . Please sir it is very helpful for us..
I took inspiration from this video for two examples for the solution of dual rail power...
th-cam.com/video/IOWBzwuNXaw/w-d-xo.html
um, just invert anything negative, to get positive
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