How to design a single transistor amplifier with voltage divider bias

This video simplifies the design of a small signal common emitter transistor amplifier that uses a voltage divider bias circuit on the base. Demonstration circuit is breadboarded after the design.
Thank You!

[hemlocksalazar]

You are gifted when it comes to explaining stuff, I'm proud to announce I'm listening to this on a TDA1517p I built after watching your videos. Thanks for sharing your knowledge with the world John.

[P_P]

I built lm386 amplifier using your schematic and it works really well !

[rogermcinerny]

After absolutely scouring the internet for a straightforward explanation of how to chose resistor values for a voltage devider biased transistor amplifier, this video finally explained exactly what decisions need to be made and how to make them. Thank you so much for making these videos!

[oakspines]

Concise. Brief and to the point. Back up with protoboard hookups. Good job.

[kavindugilshan]

Please make more electronics theory tutorials.
It was very interesting.
You explained that 100 times better than my electronics teacher .
Thank you !!

[xbnnqll]

As ever, you make it look simple and easy peasy. And yet, I always learn something.

[carlgradolph]

Nice job of presenting just enough detail to allow novices like me to understand how amplifiers are designed. You admit to glossing over some finer points, thus opening yourself up to accusations from the cognoscenti of either not telling or (worse) not knowing the full story. But your practical, simplified approach is worth far more to learners like me than a million hours of pontificating by "experts"!

[kugodx]

I am a beginner hobbyist and this was immensely helpful! You get a like, comment, and subscribe good sir. Looking forward to more videos!

[Blowncapacitor]

Its absolutely insane when I think about how much I've learned from you! Thank you John!

[argcargv]

The vbe reported by the transistor tester is probably at a 1ma bias current. The .65 v value is probably closer to correct at the 13 uA bias operating point of your circuit. Great intuitive explanation.

[boeingpete]

Thanks John, really helpful tutorial. I know this is a tricky topic but nicely explained without it turning into an algebra lesson. 👍

[jonlambert]

Thank you!!! Simple explanations of elementary building blocks is something been looking for, for ages! If you could do an explanation of differences for mosfet (voltage input) bjp (current input). And npn pnp using the single transistor amp format like this that would be even better 😀.

Also I'm aware of differences between purely current output with the capacitor below the transistor and current and voltage output like you have on this video but am unsure of what those differences are.

Anyway. Thank you! Great stuff 😀

[souvicknaskar]

Thank you! It's very informative video for hobbyist with simple explanation.

[qolbunsalim]

Thank you lecturer John. U explain it in simple easy applicable way.
Simple math.

[johnnytoobad]

I attempted to do this (once!) "on paper" in order to re-design a 70's vintage pre-amp circuit. I ended up using a circuit simulator (TINA) to converge the circuit for lowest THD for the gain value (+9db / stage) I was shooting for. I used MPSA18 transistors (beta of 800+) for all three stages. The end result is still working quite well. Only a small amount of negative feedback is used from the follower (output) stage. The original design used un-obtainium FETS with a max output of 5 volts (!) less than .25% THD. I was able to achieve .11% THD at 3v rms using the mpsa18s WITHOUT changing the original board design. I just needed to add RB1. However it took quite a bit of "simulator" experimenting to home-in on the proper resistor values. It's two CE stages followed by an EF stage. The original design had NO RB1. I guess you didn't need them for the FETs. but I needed Rb1 at 10 meg and Rb2 at 1 meg. The simulation failed without Rb1. (even at 10 meg!) The original design also had Rb2 at 1 meg. I believe that's the only value that didn't change. Every board level component got replaced. This was originally done as a "re-capping" project back in 2006, but a few years later, I decided to replace the entire circuit. I had NO choice but to re-design the bias network even if I wanted to use modern J-FETS (the original plan) . But I eventually switched to the low noise (easily obtainable) NPN bi-polars. I used the same 36vdc that Sony was using off of their (re-capped) PSU board. The actual Pre-amp was a SONY TA-2000f (circa 1975). Except now it's got a re-built line amp. The line amp (20db) gain stage is a classic textbook design. Twin (daisy chained) CE stages followed by an EF stage, all cap-coupled. THD and transient response are much better than the original circuit.

[fredfabris]

Great video! I would have been curious to see it’s performance at higher input levels. I would have liked to see where and how it clipped. I also would have liked to see how a transistor with a different measured hfe acted. Thanks for all your hard work. Like others have said, you are an asset to YouTube and possess a gift for teaching.

[urkolarranaga]

I’m happily hooked to this channel, just fantastic!!

[idahorefugeecommunityassoc]

Thank you so much dear human brother. You donated your knowledge.

[tektech]

Thank you for sharing your practical knowledge and posting this video. I specifically enjoy your talent for explaining how things work. It's a rare ability. Would you consider in a future video designing emitter follower? They are simple to build and work great in a wide range of frequencies, from audio to RF.

[taintedmeat]

I've discovered some of the Beta tests on these meters and testers are pretty far off so if I need an accurate Beta measurement I will get the actual base and collector measurements and then use the formula B=Ic/Ib ...this always works out. Thanks !