The main problem I have noticed why people don't know how to use transistors, is the teachers. They are starting electronics with transistors, and immediately dive into the deep end of transistor analysis and different types of transistors, without actually ever explaining what they are and what they are used for. Even on the first introduction to electronics, teachers start throwing around words like FETs, BTJs , IGBTs, NPN, PNP, emitter, controller, base etc. never actually telling students what those acronyms mean. For example, a few years ago, I participated in 1st year students electronics course in an University as an undercover student to troubleshoot why everyone was failing these lessons. I have a few engineering degrees and although my electronics degree is from the the early 2000s, I could barely follow the class and had to correct the teacher several times on critical (possibly fatal) theoretical errors, because he thought they were so obvious everyone would know that he was talking about only a very limited use case with a lot of safety precautions in place. With the excuse that I had "just read on a the internet that isn't it like this instead?", since I couldn't just let those things pass. Then the after the 2nd week, theory was over, and we moved to lab to start building a full audio-amplifier. Basically, everyone just followed instructions, but didn't understand anything they were doing, and learned even less. I won't name the school, state or country The teacher was a former electronics virtuoso from a top name company (that still did consulting for them, but had downshifted to teaching), but he was so disconnected from beginners, he was talking and teaching to them as they were all post-graduate students, and just excepted everyone to be at that level coming in to the first electronics lesson. Also, for some messed up reason, physics I and II were scheduled AFTER the electronics courses.
Many many thanks for explaining how easy it is to use these little devils. I have lots of transistors, but never use them and stick to simple circuits for fun, but now that you have explained them to me, I will start to use them in my circuits and get all the benefits that they bring as well as enjoying electronics more. Thank you so much, Joe
Ahhh, this is outstanding stuff for the audience you intended this for & I most definitely count myself as part of it! I'm in the "Super eager-to-learn electronics enthusiast w/zero formal schooling & 100% self-taught" & transistors are like the Next Big Step for me that I've procrastinated LIKE CRAZY on implementing in any of my projects all just bc of how intimidatingly arcane it was for me to try & learn even the basics about them w/o any primer. Pretty much any "intro" to transistors & semiconductors in general might as well be written in sanskrit if you don't have a grasp on the lexicon going in, so thank you for the effort to help bridge the gap for people like me!
"trite" - awesome. that is a better word choice than most native speakers would make. i had to watch this again after your recent transistor magnum opus.
Another excellent review deepening my understanding. I'm an Amateur Radio operator and electronics hobbyist since childhood. This is an area that I clearly grasp but still was not fully confident. Logic was easy, but other applications are now much more clear. My Sansui QRX 7400a is clearly an example of class A B amplifying. But PWM and other applications I was not quite clear on. Your examples are very helpful, thanks again..
Excellent Explanation . you taught me so many things in just 27 mins which my college failed to teach in four years. please keep making the videos which is very helpful for knowledge seekers like me. Thank you so much
Exactly what I'm looking for. Not just the bare explanation of how a transistor works, but even several examples what they are doing and above all why that's important. Cause, I never understand realy why I should use a transistor as a switch after e.g. an push button. Direktly saved in my learning list! Thanks
Salam dorud. I suspect you're Iranian. That makes you the second great Iranian electronics teacher I've found on YT. You're tutorials and contents are fantastic and you're channel will grow fast. I'm from Tehran.
I tried to better understand how circuit at 9:21 works (mosfet as a switch for another circuitry) and here is what I came up with: 1. P-Channel MOSFET Operation with Knock Sensor: In this circuit, the P-channel MOSFET has its source connected to the positive terminal of the battery and the drain connected to the "main circuit" (whatever load or circuitry it controls). The knock sensor temporarily connects the gate of the MOSFET to ground when triggered by a knock. This grounding lowers the gate voltage, creating a sufficient gate-source voltage difference to turn the MOSFET on, allowing current to flow from the source to the drain and powering the "main circuit." 2. Role of the Pull-Up Resistor: The resistor between the positive terminal of the battery and the gate of the MOSFET acts as a pull-up resistor. Once the knock sensor disconnects (i.e., it stops grounding the gate), the pull-up resistor raises the gate voltage back to the battery level. By restoring the gate voltage, the MOSFET turns off, as the gate-source voltage difference is eliminated or reduced to the point where the MOSFET no longer conducts. This ensures that the MOSFET only stays on as long as the knock sensor is grounding the gate. 3. Role of the Green Wire: The green wire here could be intended as a way to influence the gate voltage in a delayed fashion. For example, if the green wire connects to a timing circuit (like an RC network or a secondary transistor), it could slowly discharge or recharge the gate, allowing the MOSFET to stay on for a set duration after the knock sensor releases. Essentially, if the green wire is part of a timing mechanism, it would allow for delayed turn-off, extending the time the main circuit is powered even after the knock sensor is no longer active. In this configuration, the green wire would indeed control the timing independently of the immediate action of the pull-up resistor. This approach combines the instant effect of the knock sensor with a gradual control mechanism via the green wire, allowing for more control over how long the MOSFET stays on after the knock. This arrangement provides flexibility: the MOSFET can turn off right away if the knock is brief, or it can stay on for a pre-defined time if the green wire is connected to a timing circuit.
Hi Electronic Wizard. Thank you for the video. Could you please help me to assess if my understanding of the MOSFET as a touch sensor at 10:29 is correct? 1. MOSFET Configuration: The IRF640 MOSFET is configured in a way that its gate (G) is sensitive to touch. The drain (D) is connected to the motor (MOT) and the source (S) is grounded. 2. Gate Capacitor Effect: MOSFETs have an inherent gate capacitance, which is very small. This gate capacitance can be charged up by a small amount of current, such as the one from your finger when touching the circuit. 3. Touch as a Charge Source: When you touch the exposed metal connected to the gate, the tiny electric charge from your body (called Electrostatic Induction, or ESD) is enough to slightly charge the gate of the MOSFET, changing the voltage level at the gate. 4. Gate Voltage Control: When the gate reaches a high enough voltage, it allows current to flow from the drain to the source, turning on the MOSFET and powering the motor. This means the motor will activate when you touch the gate. 5. Resistor Discharge: The 10 MΩ resistor connected between the gate and ground serves to discharge the gate capacitance when the touch is removed. With this high resistance, the discharge happens slowly, allowing the motor to turn off gradually after you remove your touch. 6. Improving Sensitivity: A spiral or touchpad pattern can be used instead of simple electrodes to improve sensitivity, making it more reliable and responsive to touch. In summary, touching the gate causes a slight voltage increase due to your body’s electrostatic charge, turning the MOSFET on and powering the motor. The 10 MΩ resistor discharges this charge when you stop touching, turning the motor off. On the role of the resistor: 1. Role of the Resistor in Setting Gate Voltage: The 10 MΩ resistor serves to discharge the gate capacitor when there is no touch. However, it also influences the voltage at the gate when you do touch it. When you touch the gate terminal, a small current flows through your body, charging the gate capacitance through the skin’s resistance. The 10 MΩ resistor provides a path to ground, so it creates a voltage divider effect with the effective resistance of your skin. 2. Skin Resistance and Resistor Value: The resistance of human skin can vary widely, generally ranging from hundreds of kilo-ohms to several mega-ohms, depending on factors like moisture and contact pressure. If your skin resistance is, say, around 1 MΩ, it combines with the 10 MΩ resistor to form a voltage divider, which can set the gate voltage closer to the threshold voltage of the MOSFET. The higher the value of the resistor, the more it “favors” the gate retaining a charge (keeping it “on”) after touch is detected, since it provides only a slow discharge path. 3. Choosing the Resistor Value Based on Skin Resistance: If the resistor is too low (e.g., 100 kΩ), it would discharge the gate too quickly, and your touch might not increase the voltage sufficiently to activate the MOSFET reliably. On the other hand, if the resistor is too high (e.g., 100 MΩ), the gate might remain charged longer than desired, making it less responsive. Thus, a resistor in the range of 5-10 MΩ strikes a balance, ensuring the gate reaches a high enough voltage when you touch it, while also discharging reasonably when you remove your touch. In summary: • The resistor helps achieve the necessary gate voltage by creating a voltage divider effect with the skin resistance. • Skin resistance influences the resistor choice, as a higher resistor value is needed to work with the variable (but high) resistance of human skin and ensure reliable gate voltage change upon touch.
@@Enigma758 A common collector (CC) amplifier or "emitter follower" is a good circuit to use when you want to apply a constant (but variable as required) voltage to a load that varies in impedance. Remember that an ideal voltage source has zero output impedance - the voltage stays constant no matter what current is drawn from the source. The CC amplifier has high input impedance and low output impedance. The output impedance isn't zero, so you don't get a perfect voltage source, but it is low. Just what the ratio of input impedance to output impedance actually is depends on the current gain of the transistor. The higher the gain the higher the ratio of input to output impedance. That gain will vary somewhat from one unit to another of the same type and will vary with temperature. Usually with a DC motor with brushes what you want to do is control the speed , which is reasonably proportional to the applied voltage. If the mechanical load increases while the applied voltage is kept constant, the current increases, and vice versa. That low output impedance of the CC amp is just what you need. Overall the performance isn't great, but can be quite adequate for lots of purposes. (If you need really good speed control you'd typically use a tachometer in a closed-loop system, though you can do a pretty good job by measuring the back-EMF from the motor, which tends to be very linear with speed). There are circuits where you might add some extra resistance in the emitter circuit of a CC amp but that moves the circuit farther away from being an ideal voltage source if the load is in series with the added resistor. If a CC amp is used as the final output stage of an amplifier with feedback, sometimes a small resistance is used to isolate capacitance that may be present with the load. Capacitance can cause a phase shift that can play havoc with the stability of the system and the resistor can mitigate the problem. This is common with audio power amplifiers. Both JFETs and MOSFETs can be used in "source follower" (common drain) circuits for extremely high input impedance. The difference between gate voltage and source voltage is not as well defined as with BJTs.
Your approach to teaching is unique, practica, clear and previous!! It’s seems all so natural and easy to explain these topics your way!! But it’s clear that there is a lot of preparation An planning before each video. Thank you very much!! I just discovered you today but U will come back often!
I would not call the simple 2-transistor current limiter a "switch." The main transistor is essentially switched ON below the current limiting threshold, but as that threshold is approached the whole circuit begins to operate in linear mode. It is important to remember that the main transistor power dissipation may be quite high and a heatsink may be required. This circuit isn't high precision and you'd get a moderate amount of variation from one unit to another, but it is plenty good enough for lots of applications.
Good points, the circuit is not high precision, you have to add some other components to make it more precision. Components like OPAMP. I will explain it in one of my upcoming videos 👍
Absolutely outstanding presentation which leaves more room for more. Particularly interested in RF amplification applications and also discussions about filtering in all types of amplification using transistors. Terrific presentation as usual. Many thanks. 73, NZ5i
Great way of high side switching n-channel mosfets.... Use photovoltaic opto isolators. The isolator's output can be floated on the mosfets source. Thus gate-source voltage can always go high enough to ensure full on.
Photovoltaic couplers are generally pretty slow and the last time I looked (years ago) they were quite expensive. Still, they are a good solution for some applications.
Thank you sir, now I know how touch buttons on certain old elevators work on the inside ! I’m a lift mechanic and nobody could explain it to me on a component level!
Yes it's like sales people that read from the back of the box, but this is all very interesting. I guess there is an attitude to things that, nobody expects anyone to use a soldering iron any more.
Nope, this configuration is called "Common collector" the circuit is OK. There is a dedicated video about this circuit on the channel. Look for DC motor speed controller video on the channel for detailed information on this subject.
very very very very very useful channel! Thank you a lot , continue like that 🙏 I have idea why You sir don't use a plastic table to draw not loose paper 🙂.
Well, I'm positive i learned something new - but i also feel i may need to watch this many more times! Easy to understand once you get used to his accent and speech speed.
Good video! I would like to see more information on how to create constant current supply for led and laser diodes. There’s not a lot of very good videos on cc supply. Cheers!
Great contents as always ,congrats. Could you make a video explaining inductor the same as this video(example: how exactly inductor oposes the Change in current,)please Iam stuck in electronics until I grasp this
@elewizard I have similar vice type and without filter the sound is not good. In order to avoid post processing my audio every time I use Sure MV7 with their software. Once you setup the filters the audio is good every time. My configuration for creating TH-cam videos is: I use SurePlus Motiv for the microphone , then it goes into NVidia Broadcast as I apply some extra filters and background blur, and then it goes into OBS Studio. I don't use filters in OBS though it has plenty. Just to setup my scenes, screen. My first video had terrible audio when I used my Webcam microphone.
@@elewizard its true. Not only for integration of small electronics into big machines, but you can add complexity to circuits simply by having an entire secondary circuit connected via transistor. I use them for all sorts of stuff, almost as much as I use diodes.
When switching a motor or anything else with a coil, use a feedback diode! This is to avoid/cancel back EMF. Without it can ruin your funny experiments with transistors pretty soon.
One type of transistor serves as an inverter in one piece. Solar power banks use it for the Nokia 5110,6110,7110 series. The transistor can invert the 3.2v safely to 6.9 v when loaded, and can operate a 6 v cleaner motor at high speed from a little 3.7 v Nokia battery.
wow washing someone describing my hobby in such a confusing way troubles me. first vacuum tubes and FET field Effect Transistors are voltage contorled devices. a BJT is NOT Binary Junction Transistors are current controlled. I stopped counting at 30 misleading statements, If anyone wants to learn electronics this is not the channel. a great example of " If you can't dazzle them with brilliance baffle them with BS "
The speed at which you run your drawings and the practicals on already assembled components on the breadboard make the video useless for beginners. If you could take some time to explain the circuit as you draw and also explain when you put components on the breadboard...that would make the video a very valuable source of learning for the beginners. Thank you!
Yeah, WOW man. Wizard actual. You seem to use English far better than many of my American neighbors lol. I'm already using a custom open source 'Solid State Tesla oscillator' circuit (by Master Ivo), employing SiC power mosfets, running a [bifilar pancake] Tesla Coil based 'single wire transmission line', improvising simple little analog circuitry for probing my system. Even so, this vid managed to: a. Rock my world b. knock my socks c. cause me to execute a backflip Question: How would YOU replicate Tesla's trick of using an old telephone handset to 'listen in' for null points along a [scalar/longitudinal]TX line? F resonant is around 120kHz, must i use a heterodyne to get audible tones, or can it be managed more simply? I think Tesla was also using telephone handset with a 'coherer' RF detector to make just periodic 'beeps' out around NYC while his transmitter was oscillating. A simple 'periodic beeper' to sound off when my step-down 'receiver' transformer is getting power from the line (or spherical terminal), would be helpful for me to demonstrate reception inside a grounded faraday cage too - any tips, my guy? ❤ cold
The main problem I have noticed why people don't know how to use transistors, is the teachers. They are starting electronics with transistors, and immediately dive into the deep end of transistor analysis and different types of transistors, without actually ever explaining what they are and what they are used for. Even on the first introduction to electronics, teachers start throwing around words like FETs, BTJs , IGBTs, NPN, PNP, emitter, controller, base etc. never actually telling students what those acronyms mean.
For example, a few years ago, I participated in 1st year students electronics course in an University as an undercover student to troubleshoot why everyone was failing these lessons. I have a few engineering degrees and although my electronics degree is from the the early 2000s, I could barely follow the class and had to correct the teacher several times on critical (possibly fatal) theoretical errors, because he thought they were so obvious everyone would know that he was talking about only a very limited use case with a lot of safety precautions in place. With the excuse that I had "just read on a the internet that isn't it like this instead?", since I couldn't just let those things pass. Then the after the 2nd week, theory was over, and we moved to lab to start building a full audio-amplifier. Basically, everyone just followed instructions, but didn't understand anything they were doing, and learned even less. I won't name the school, state or country
The teacher was a former electronics virtuoso from a top name company (that still did consulting for them, but had downshifted to teaching), but he was so disconnected from beginners, he was talking and teaching to them as they were all post-graduate students, and just excepted everyone to be at that level coming in to the first electronics lesson. Also, for some messed up reason, physics I and II were scheduled AFTER the electronics courses.
You are not alone even in other industries in tech
Many many thanks for explaining how easy it is to use these little devils. I have lots of transistors, but never use them and stick to simple circuits for fun, but now that you have explained them to me, I will start to use them in my circuits and get all the benefits that they bring as well as enjoying electronics more.
Thank you so much,
Joe
Glad to hear that, I am so happy for motivating you, 🥂
Ahhh, this is outstanding stuff for the audience you intended this for & I most definitely count myself as part of it! I'm in the "Super eager-to-learn electronics enthusiast w/zero formal schooling & 100% self-taught" & transistors are like the Next Big Step for me that I've procrastinated LIKE CRAZY on implementing in any of my projects all just bc of how intimidatingly arcane it was for me to try & learn even the basics about them w/o any primer. Pretty much any "intro" to transistors & semiconductors in general might as well be written in sanskrit if you don't have a grasp on the lexicon going in, so thank you for the effort to help bridge the gap for people like me!
Thank you so much for being a part of the community.
I appreciate your kind words ❤️
"trite" - awesome. that is a better word choice than most native speakers would make. i had to watch this again after your recent transistor magnum opus.
Thank you my friend for encouraging me ❤️❤️❤️❤️
BTW, gratitude for the £2 Super Thanks support! 🙌
Another excellent review deepening my understanding. I'm an Amateur Radio operator and electronics hobbyist since childhood. This is an area that I clearly grasp but still was not fully confident. Logic was easy, but other applications are now much more clear. My Sansui QRX 7400a is clearly an example of class A B amplifying. But PWM and other applications I was not quite clear on. Your examples are very helpful, thanks again..
Glad it was helpful! Thank you for sharing and watching
Thanks!
Thank you so much my friend ❤️
No word of a lie, but I'm in absolute awe of your encyclopedic knowledge of electronics. Wow!
Thank you for the compliment, I'll try to make more videos like this 👍
Excellent Explanation . you taught me so many things in just 27 mins which my college failed to teach in four years. please keep making the videos which is very helpful for knowledge seekers like me. Thank you so much
Happy to help. I will make more videos like this 👍
Showing the practical applications really helps, thank-you!
Glad it was helpful! Cheers 🥂
In a simple and short words "you are just amazing man"
Thank you so much ❤️❤️❤️❤️
Exactly what I'm looking for. Not just the bare explanation of how a transistor works, but even several examples what they are doing and above all why that's important.
Cause, I never understand realy why I should use a transistor as a switch after e.g. an push button.
Direktly saved in my learning list!
Thanks
Glad it was helpful 😃
I will try to make more videos of this type 👍
Yet another great educational video. Thank you!
My pleasure!🫡
I discovered you few hours ago. I subscribed after first 5 minutes. Thank you for your work. Your content is so good. Greetings from Romania.
Welcome aboard! Thank you for watching 😊
Salam dorud. I suspect you're Iranian. That makes you the second great Iranian electronics teacher I've found on YT. You're tutorials and contents are fantastic and you're channel will grow fast. I'm from Tehran.
Hi my friend. Glad you think so, accept my warm welcomes from ardabil
@@elewizard Thank you sir. Benım anne tarafim de Ardebidiler. Sağolun abi.
this is one of the best videos i've seen about transistors. i found this so helpful thank you :)
Glad to hear that, cheers 🥂
I refreshed my memories especially about Switching, for me, transistors will always be switches though 😂 thank you so much for this video
You're so welcome! Thank you for watching 🍻
I tried to better understand how circuit at 9:21 works (mosfet as a switch for another circuitry) and here is what I came up with:
1. P-Channel MOSFET Operation with Knock Sensor:
In this circuit, the P-channel MOSFET has its source connected to the positive terminal of the battery and the drain connected to the "main circuit" (whatever load or circuitry it controls).
The knock sensor temporarily connects the gate of the MOSFET to ground when triggered by a knock. This grounding lowers the gate voltage, creating a sufficient gate-source voltage difference to turn the MOSFET on, allowing current to flow from the source to the drain and powering the "main circuit."
2. Role of the Pull-Up Resistor:
The resistor between the positive terminal of the battery and the gate of the MOSFET acts as a pull-up resistor. Once the knock sensor disconnects (i.e., it stops grounding the gate), the pull-up resistor raises the gate voltage back to the battery level.
By restoring the gate voltage, the MOSFET turns off, as the gate-source voltage difference is eliminated or reduced to the point where the MOSFET no longer conducts. This ensures that the MOSFET only stays on as long as the knock sensor is grounding the gate.
3. Role of the Green Wire:
The green wire here could be intended as a way to influence the gate voltage in a delayed fashion. For example, if the green wire connects to a timing circuit (like an RC network or a secondary transistor), it could slowly discharge or recharge the gate, allowing the MOSFET to stay on for a set duration after the knock sensor releases.
Essentially, if the green wire is part of a timing mechanism, it would allow for delayed turn-off, extending the time the main circuit is powered even after the knock sensor is no longer active.
In this configuration, the green wire would indeed control the timing independently of the immediate action of the pull-up resistor. This approach combines the instant effect of the knock sensor with a gradual control mechanism via the green wire, allowing for more control over how long the MOSFET stays on after the knock.
This arrangement provides flexibility: the MOSFET can turn off right away if the knock is brief, or it can stay on for a pre-defined time if the green wire is connected to a timing circuit.
Your videos are helpful and you are a great instructor!
Glad you think so!🍻
Hi Electronic Wizard. Thank you for the video. Could you please help me to assess if my understanding of the MOSFET as a touch sensor at 10:29 is correct?
1. MOSFET Configuration: The IRF640 MOSFET is configured in a way that its gate (G) is sensitive to touch. The drain (D) is connected to the motor (MOT) and the source (S) is grounded.
2. Gate Capacitor Effect: MOSFETs have an inherent gate capacitance, which is very small. This gate capacitance can be charged up by a small amount of current, such as the one from your finger when touching the circuit.
3. Touch as a Charge Source: When you touch the exposed metal connected to the gate, the tiny electric charge from your body (called
Electrostatic Induction, or ESD) is enough to slightly charge the gate of the MOSFET, changing the voltage level at the gate.
4. Gate Voltage Control: When the gate reaches a high enough voltage, it allows current to flow from the drain to the source, turning on the MOSFET and powering the motor. This means the motor will activate when you touch the gate.
5. Resistor Discharge: The 10 MΩ resistor connected between the gate and ground serves to discharge the gate capacitance when the touch is removed. With this high resistance, the discharge happens slowly, allowing the motor to turn off gradually after you remove your touch.
6. Improving Sensitivity: A spiral or touchpad pattern can be used instead of simple electrodes to improve sensitivity, making it more reliable and responsive to touch.
In summary, touching the gate causes a slight voltage increase due to your body’s electrostatic charge, turning the MOSFET on and powering the motor. The 10 MΩ resistor discharges this charge when you stop touching, turning the motor off.
On the role of the resistor:
1. Role of the Resistor in Setting Gate Voltage: The 10 MΩ resistor serves to discharge the gate capacitor when there is no touch. However, it also influences the voltage at the gate when you do touch it. When you touch the gate terminal, a small current flows through your body, charging the gate capacitance through the skin’s resistance. The 10 MΩ resistor provides a path to ground, so it creates a voltage divider effect with the effective resistance of your skin.
2. Skin Resistance and Resistor Value: The resistance of human skin can vary widely, generally ranging from hundreds of kilo-ohms to several mega-ohms, depending on factors like moisture and contact pressure. If your skin resistance is, say, around 1 MΩ, it combines with the 10 MΩ resistor to form a voltage divider, which can set the gate voltage closer to the threshold voltage of the MOSFET. The higher the value of the resistor, the more it “favors” the gate retaining a charge (keeping it “on”) after touch is detected, since it provides only a slow discharge path.
3. Choosing the Resistor Value Based on Skin Resistance: If the resistor is too low (e.g., 100 kΩ), it would discharge the gate too quickly, and your touch might not increase the voltage sufficiently to activate the MOSFET reliably. On the other hand, if the resistor is too high (e.g., 100 MΩ), the gate might remain charged longer than desired, making it less responsive. Thus, a resistor in the range of 5-10 MΩ strikes a balance, ensuring the gate reaches a high enough voltage when you touch it, while also discharging reasonably when you remove your touch.
In summary:
• The resistor helps achieve the necessary gate voltage by creating a voltage divider effect with the skin resistance.
• Skin resistance influences the resistor choice, as a higher resistor value is needed to work with the variable (but high) resistance of human skin and ensure reliable gate voltage change upon touch.
You electronics freaks are a rare breed and I don’t mean that in a bad way. How you people understand how those components work is beyond me.
Experience, that is the key 🗝
Isn't there typically an emitter resistor for a common collector configuration?
it depends on the load, the load may need a resistor or not!
@@elewizard Thanks, I see that, but won't a load such as a motor vary in impedance at different speeds?
@@Enigma758
A common collector (CC) amplifier or "emitter follower" is a good circuit to use when you want to apply a constant (but variable as required) voltage to a load that varies in impedance.
Remember that an ideal voltage source has zero output impedance - the voltage stays constant no matter what current is drawn from the source.
The CC amplifier has high input impedance and low output impedance. The output impedance isn't zero, so you don't get a perfect voltage source, but it is low. Just what the ratio of input impedance to output impedance actually is depends on the current gain of the transistor. The higher the gain the higher the ratio of input to output impedance. That gain will vary somewhat from one unit to another of the same type and will vary with temperature.
Usually with a DC motor with brushes what you want to do is control the speed , which is reasonably proportional to the applied voltage. If the mechanical load increases while the applied voltage is kept constant, the current increases, and vice versa. That low output impedance of the CC amp is just what you need. Overall the performance isn't great, but can be quite adequate for lots of purposes. (If you need really good speed control you'd typically use a tachometer in a closed-loop system, though you can do a pretty good job by measuring the back-EMF from the motor, which tends to be very linear with speed).
There are circuits where you might add some extra resistance in the emitter circuit of a CC amp but that moves the circuit farther away from being an ideal voltage source if the load is in series with the added resistor. If a CC amp is used as the final output stage of an amplifier with feedback, sometimes a small resistance is used to isolate capacitance that may be present with the load. Capacitance can cause a phase shift that can play havoc with the stability of the system and the resistor can mitigate the problem. This is common with audio power amplifiers.
Both JFETs and MOSFETs can be used in "source follower" (common drain) circuits for extremely high input impedance. The difference between gate voltage and source voltage is not as well defined as with BJTs.
Yes, it varies. So what? There is no need to a resistor there
@@elewizard OK
Your approach to teaching is unique, practica, clear and previous!!
It’s seems all so natural and easy to explain these topics your way!! But it’s clear that there is a lot of preparation An planning before each video.
Thank you very much!!
I just discovered you today but U will come back often!
Wow, glad you think so, Thank you! 😃
Thank you for taking the time to do these videos!
Thank you for being a part of this journey! ❤️
Thanks for practical applications.
You are welcome!❤️❤️❤️
3:02 "Since BD139 is an NPN type BJT transistor, it is better to use it to switch Ground voltage"
but why ?
There are several reasons. See this video
th-cam.com/video/L0QraSYq8tw/w-d-xo.htmlsi=gcBXkraxCiDBjlcK
Excellent content with good examples! Thank you!
You're very welcome! Cheers 🥂
this is the content i wish i had a long time ago…very nice!
Glad to hear that 😃
I would not call the simple 2-transistor current limiter a "switch."
The main transistor is essentially switched ON below the current limiting threshold, but as that threshold is approached the whole circuit begins to operate in linear mode.
It is important to remember that the main transistor power dissipation may be quite high and a heatsink may be required.
This circuit isn't high precision and you'd get a moderate amount of variation from one unit to another, but it is plenty good enough for lots of applications.
Good points, the circuit is not high precision, you have to add some other components to make it more precision. Components like OPAMP. I will explain it in one of my upcoming videos 👍
Do you have any videos on capacitor dump circuit? Thank you sir.
Not yet 🙃
Awesome video, I will be waiting for more.
More to come!
Absolutely outstanding presentation which leaves more room for more. Particularly interested in RF amplification applications and also discussions about filtering in all types of amplification using transistors. Terrific presentation as usual. Many thanks. 73, NZ5i
Glad it was helpful! Thank you for watching ❤️
Man, this is a very comprehensive video with very interesting applications. Thank you so much!
Thank you for watching and supporting me ❤️
Amazing channel. You are a stellar teacher. Subscribed
Thanks for watching and for the encouraging comment!
Your support motivates me to create more content!
You are great not because of details of electronics but also easy understandable english
Thank you dude, not because of your support, but also because of your kindness 😉
"Wizard" - beautifully organized components in background - in-deph articulation of the topic
yes yes yes
So glad you think so
Just subscribed your channel for your beautiful explanation with practical knowledge. Keep it up. Lots of love from INDIA..
You are very welcome my Indian friend 😃
Excellent video. Thanks for putting time to make it 🎉
My pleasure 😊
as i am mechanical engineer your deep discusion is awaysome
So nice of you 😊
Super explanation. ❤
Thank you 🙂
Great way of high side switching n-channel mosfets.... Use photovoltaic opto isolators. The isolator's output can be floated on the mosfets source. Thus gate-source voltage can always go high enough to ensure full on.
Thanks for sharing❤️
Photovoltaic couplers are generally pretty slow and the last time I looked (years ago) they were quite expensive. Still, they are a good solution for some applications.
What a great approach. I grew up at age 10 playing with 1n914
I grew up with LM7805 😅
Great regulators.
Your description is very helpfull ever
I appreciate your kind words! 😊
Thank you sir, now I know how touch buttons on certain old elevators work on the inside ! I’m a lift mechanic and nobody could explain it to me on a component level!
Touch sensors can be made by using several different methods. Now you learned one of them 🍻
Yes it's like sales people that read from the back of the box, but this is all very interesting.
I guess there is an attitude to things that, nobody expects anyone to use a soldering iron any more.
The best text definitions of electronic components greatly pales in comparison to your examples, diagrams, breadboard, and oscilloscope.
Wow, thanks!
At 25.04, should the motor not be connected to the collector?
Nope, this configuration is called "Common collector" the circuit is OK.
There is a dedicated video about this circuit on the channel. Look for DC motor speed controller video on the channel for detailed information on this subject.
Thanks for the video.
You are most welcome
Good info.
Glad you think so!
Wonderful 👍
Thank you! Cheers!
Nice explanation is from nice one
Keep watching❤️
16:50 نفس الإجراء يستخدم في مكبر الصوت للخلق استقرار في التيار عند سخونة الترانزيستر
Thank you for the point
Great video. Didnt you have another channel ?
I had one, but it is not available now 😉
Super sir 🙏
Glad to hear that
very very very very very useful channel!
Thank you a lot , continue like that 🙏
I have idea why You sir don't use a plastic table to draw not loose paper 🙂.
You are very welcome ❤️
Thank you for the point
Thank you for the explanation, I learned a lot. I subscribed to your channel. I hope to learn much more. Blessings to you. Best regards.
Thanks and welcome ❤️❤️
Thakn you so much sir we need your Gidence
Anyone not give information like this
You are most welcome ❤️
I will do my best
Great video!
Glad you enjoyed it
Well, I'm positive i learned something new - but i also feel i may need to watch this many more times! Easy to understand once you get used to his accent and speech speed.
Keep watching. And I will keep improving my accent and speech 👍😊
pls teach other applications of the transistor
Will try 👍
Good video! I would like to see more information on how to create constant current supply for led and laser diodes. There’s not a lot of very good videos on cc supply. Cheers!
Noted! Thank you❤️
S0 nice thanks sir
You are most welcome
Nice video, well done, thanks for sharing it with us :)
Thanks for watching!😊
Much obliged.
Thank you so much ❤️
Sir, please make video on remaining application also..
OK, 👍
Sir, I love how you teach~
Wow, thank you ❤️❤️
great. I am your Fan.
So nice of you ❤️
Thank you 👍👍👍
You're welcome
Great contents as always ,congrats.
Could you make a video explaining inductor the same as this video(example: how exactly inductor oposes the Change in current,)please Iam stuck in electronics until I grasp this
Yes, it is in my todo list 🙃
@@elewizard waiting for it
I would happily pay 50-60$ to get a pdf/book with those informative videos' contents
😃
داداش دمت گرم عالی بود
Thank you dude, keep watching ❤️
nice
Thanks
Those things u mentioned at the end are what I thought you will talk about in this video.
My bad 😁
i sure could use your help
It is my pleasure to help you ❤️
sri,could make a vedio about the RF remote control circuit
Certainly, it is my todo list 👍
Well done
Thank you ❤️
TRAN = Vietnam for - I learned that!
Good info, the audio makes it hard to listen though. Please process your audio or by a good microphone
Thanks for the point ❤️
@elewizard I have similar vice type and without filter the sound is not good. In order to avoid post processing my audio every time I use Sure MV7 with their software. Once you setup the filters the audio is good every time. My configuration for creating TH-cam videos is: I use SurePlus Motiv for the microphone , then it goes into NVidia Broadcast as I apply some extra filters and background blur, and then it goes into OBS Studio. I don't use filters in OBS though it has plenty. Just to setup my scenes, screen. My first video had terrible audio when I used my Webcam microphone.
Very interesting, thank you for sharing
I want occilation circuit with a single transistor with detailed inner and outer function and working of transistor
Will try 👍
Thank you for suggestion
transistors have insane applications, i dont see how people could struggle with em.
Maybe
@@elewizard its true. Not only for integration of small electronics into big machines, but you can add complexity to circuits simply by having an entire secondary circuit connected via transistor. I use them for all sorts of stuff, almost as much as I use diodes.
Thank you for sharing 👍❤️
This man ❤❤❤❤❤
Thank you 😎
Thank you
You're welcome
Perfect sir
Thank you so much
Please make a wireless radio receiver circuit using transistor...
Will do
you are besttttttt
So nice of you ❤️
That's what I'm trying to do switching the whole circuit without passive power drain, but I have yet to find a suitable BJT transistor with enough Hfe
Use alltransistors.com to find suitable part number
You sadly forgot about/didn't cover the capacitance multiplier circuit, works like a charm..
Yes, I didn't cover cap multiplier and also many other usages of transistors to keep video time reasonable
tesekkurler gardas!
Thank you too my friend ❤️❤️❤️
When switching a motor or anything else with a coil, use a feedback diode! This is to avoid/cancel back EMF. Without it can ruin your funny experiments with transistors pretty soon.
Yeah, this point is covered in another video of mine 👍👍
💖💖💖💖
❤️❤️❤️❤️
❤❤❤❤
Welcome abdulbari❤️
👌👍
❤️❤️❤️❤️❤️
🤯
One type of transistor serves as an inverter in one piece. Solar power banks use it for the Nokia 5110,6110,7110 series. The transistor can invert the 3.2v safely to 6.9 v when loaded, and can operate a 6 v cleaner motor at high speed from a little 3.7 v Nokia battery.
Transistor is ASS ( Amplify , Sensing , Switching ) -------thank you for clearing it
Interesting naming, ASS 😅
Yo do not explain base resistor calculation collector emitter current 😢
I have described it in another video
@elewizard give link plz and how to use transistor as an amplifier plz make vedio
درود آقای مهندس و خسته نباشی آدرس پیج فارسی تون چیه.؟
Hi there, @Artamicro
استاد ما انگلیسی نمیفهمیم چه کنیم؟
دلمون خوش بود یکی فارسی خوشگل توضیح میده که شما هم زدی کانال لندن
Try improving your English, so you can use many high quality content ❤️ try it my friend, you can do it
wow washing someone describing my hobby in such a confusing way troubles me. first vacuum tubes and FET field Effect Transistors are voltage contorled devices. a BJT is NOT Binary Junction Transistors are current controlled. I stopped counting at 30 misleading statements, If anyone wants to learn electronics this is not the channel. a great example of " If you can't dazzle them with brilliance baffle them with BS "
Thank you so much for your feedback ❤️
The speed at which you run your drawings and the practicals on already assembled components on the breadboard make the video useless for beginners.
If you could take some time to explain the circuit as you draw and also explain when you put components on the breadboard...that would make the video a very valuable source of learning for the beginners.
Thank you!
Thank you for your feedback.
I'll consider that in upcoming videos
Yeah, WOW man. Wizard actual. You seem to use English far better than many of my American neighbors lol.
I'm already using a custom open source 'Solid State Tesla oscillator' circuit (by Master Ivo), employing SiC power mosfets, running a [bifilar pancake] Tesla Coil based 'single wire transmission line', improvising simple little analog circuitry for probing my system. Even so, this vid managed to:
a. Rock my world
b. knock my socks
c. cause me to execute a backflip
Question:
How would YOU replicate Tesla's trick of using an old telephone handset to 'listen in' for null points along a [scalar/longitudinal]TX line? F resonant is around 120kHz, must i use a heterodyne to get audible tones, or can it be managed more simply?
I think Tesla was also using telephone handset with a 'coherer' RF detector to make just periodic 'beeps' out around NYC while his transmitter was oscillating. A simple 'periodic beeper' to sound off when my step-down 'receiver' transformer is getting power from the line (or spherical terminal), would be helpful for me to demonstrate reception inside a grounded faraday cage too - any tips, my guy?
❤ cold
Emitter foliowe is not as beautiful as it was presented:)
Wow, thank you😃