36. The Darlington Pair and Sziklai Pair

An introduction to the function and use of the Darlington Pair and the Sziklai Pair.
This video replaces one I did earlier on the same topic. It improves on the explanation I gave of overall gain and corrects a current error. I am also testing my fourth microphone to improve audio quality. I have a very noisy, echo heavy shop and it seems to be a constant battle to be understandable. I need more practice with Audacity:)
NOTE: I should have mentioned it in the video. There are no 100mA plus LEDs - it's only there for a load. Should have used a resistive load. I will speak to the staff about this!!!

[@grahamhall2662]

Great lesson. Makes me realize how little I know about electronics. However I was able to follow the gist of your presentation, found the theory and especially the practical demo fascinating, thank you.

[@user-su5sq5ib3i]

I am so happy I found your channel. Your explanations are much much better that my teachers

[@TheOffsetVolt]

Well, thank you very much. I always thought Q, from Star Trek knew it all though? ;)

[@Sarth_draws]

Great video .very informative.

[@Thefarnworth1]

Excellent video, thank you for a great video.

[@stevetobias4890]

Great explanation, loved the video

[@LUMINARIASFOTON]

very cool video! It served me a lot. thanks

[@tribulationcoming]

Thanks for the tutorial. Very helpful,I work with inductors and ocylator circuits.

[@stevekoehn1675]

Thanks for filling in some gaps in my understanding.

[@antoniolucena7304]

Great work! Simple practical and balanced.Just try to improve the sound recording. Thanks!

[@TheOffsetVolt]

Thank you and you are right on the mark about the audio, I record in a noisy environment so the filter I have to use adds a tinny sound. I have most of the kinks worked out now - I hope.

[@agstechnicalsupport]

Thank you for the informative video. The video makes it easier to understand than any textbook can.

[@TheOffsetVolt]

Glad to hear it. I try to make the topic more approachable than a textbook while maintaining some of the depth. Thanks for watching.

[@daltonalessandro272]

sorry to be so offtopic but does anyone know of a tool to log back into an instagram account?? I was stupid forgot the account password. I appreciate any tips you can give me!

[@jedidiahwesley8522]

@Dalton Alessandro instablaster :)

[@daltonalessandro272]

@Jedidiah Wesley I really appreciate your reply. I found the site through google and im trying it out atm. I see it takes quite some time so I will get back to you later when my account password hopefully is recovered.

[@saarike]

Nice!

[@andymouse]

Very interesting.....cheers.

[@TheOffsetVolt]

Thanks for the visit

[@rich1051414]

I just made a sziklai pair of sziklai pairs... 10na on the base resulted in 88 amps of current. :P

[@paulanthonybridge5741]

Couple together 8 of those pairs, and it's goodbye California.......

[@playstorepj2788]

hey there awesome explanation i loved it, audio was clear for me (as i was lost in the lecture, i hardly noticed it), but if you want to improve it, you can use a condenser mic and a good audio card.(if you are not using one) i'v a quick question can i create a pair of 3904 and 5088 (for extreme gain) npn bjt's??

[@TheOffsetVolt]

The audio problems are a result of filtering I had to do to get rid of a lot of mechanical background noises. I think I have it whipped in the newer videos. Yes, the higher the beta is, the greater the current gain will be. Thanks for watching.

[@fer_fdi]

Excellent! I'd like to see a video around the Sziklai pair in audio applications. And also know if it can be done with Ge transistors (with added noise and distortion)

[@TheOffsetVolt]

Fernando, I'll see what I can come up with.

[@fer_fdi]

@@TheOffsetVolt Great! 🙏🏼

[@whatever3041]

I liked these example problems, do you think you can tell me which textbook they are from? Thanks!

[@waynec369]

Realizing this video is 4 years old now, I have a question regarding gain calculations when there are multiple transistors in parallel in the Q2 position. I ran across an old linear regulator with a 40 amp rated output using the Sziklai configuration. A 2N3055 was in the Q1 position and four 2N2955 in the Q2 position. Any idea behind gain calculations for this config?

[@TheOffsetVolt]

That's a tough one to answer without a schematic. A reasonable although uncertain assumption is that the total gain of the circuit would be 2N3055 beta X 2N2955 beat X four. The currents from the 2955s would sum in one line.

[@waynec369]

@@TheOffsetVolt thanks for the time you took to reply. It's greatly appreciated. I don't have the power supply at hand. It was one I repaired for a customer some time ago. I did, however, scratch out a schematic of the pass element section as it was something I had never seen before. It was definitely not covered in school. All four 2955s were simply connected in parallel with each other. All base leads together, all collector leads together, all emitter leads together. There were no emitter resistors either. All five transistors were mounted to the same heat sink. I read somewhere that someone postulated that mounting all the transistors on the same heat sink would eliminate the need for emitter transistors as the heat will be evenly distributed and all transistor junctions will be a nearly identical temps. Makes sense, but I have never seen that practiced, either. I have seached everywhere I can think of and asked countless EEs and no one knows. I suppose I should assemble the circuit and take some measurements in an attempt to find the answer empirically. Just as you, I assumed the gain would roughly equal the beta of the 3055 times the sum of all the beta of the 2955.

[@congchuatocmay4837]

Very high current gain doesn't necessarly translate into very high voltage gain due to the high input impedance of compound pairs resulting in limited input current change with input voltage change. I'll see if there is some way around that using current mirrors etc, I think I'd end up using 3 transistors though.

[@reptiloidx8942]

HELLO THERE . THERES A TIP142 NPN TRANSISTOR IM TRYING TO USE IN MY ONE TRANSISTOR SOUND AMP . SO TELL ME WHERE IS THE EXIT IS IT AN EMITTER OR COLLECTOR ???

[@SheikhN-bible-syndrome]

That depends on how you wired the amp if it's a common collector design then your sound output that goes to the speaker would be the emitter leg/middle leg

[@matthijshebly]

Sziklai Pair = genius

[@johnhopkins6260]

Sziklai Pair available as a single chip? (including "speed-up resistor")

[@debrajbanerjee2428]

Hey can anybody help me Identify a circuit.... Please its very urgent....

[@SheikhN-bible-syndrome]

I do believe it's pronounced like the motorcycle Suzuki

[@andromedusmoat9608]

It's actually pronounced "sick lie"

[@rickloresto9647]

Sir can i ask you a question....are you an ELECTRONICS AND COMMUNICATIONS ENGINEER.....i noticed your calculations are based on current flows...and that's making you different from ELECTRONICS HOBBYIST who are using trial and error method......i salute you

[@johnyang799]

BJT is current device. It's not uncommon to use current. On the other hand I haven't seen anyone not using current calculation for BJTs.

[@chuadodiengiadung]

I out = I in x (hfe1 x hfe2 + hfe1 + hfe2 + 1)