Topic 38: Darlington and Sziklai Pairs, Overdrive/Preamp and a Complete Power Amp

In this video examines the operation of Darlington and Sziklai transistors and their use in class-A and class-AB amplifier applications. The use of a stereo jack as a power switch for battery-operated circuits is also presented.

[@bob_mosavo]

Thanks 👍

[@jimgibson9811]

Just discovered your channel. Great content.
Now I have to go through the back catalog 😊

[@Electronics4Guitar]

Glad you found the channel. I’m just getting started and hoping to generate a lot more content and hope to keep improving the presentation 👍🏻

[@Mark_C1]

@@Electronics4GuitarI think your presentation is really good. Heavy on the maths, which I struggle with sadly. I kinda felt like I walked into a room and was like woah, this is all way above me. What even is beta 🤷‍♂️ yeah it’s that bad. I love fixing stuff but have avoided the maths. I’ll go back to the start of your videos and work on my maths a bit I guess 😬. Great content though, thank you !

[@Electronics4Guitar]

@@Mark_C1hi, Mark. Thanks for the feedback. Yeah, I definitely approach this stuff from a very technical perspective. What I envision is to eventually cover the whole field from basic RC circuits through transistors, op amps, vacuum tube amps and effects circuit operation and design. I also do plan to add a few videos that are more descriptive at some point as well.
I taught EE for nearly 40 years so it’s hard to get out of that mindset. I definitely will keep the use of calculus to a bare minimum though 👍🏻
As far as transistors go, you might start with Video 12 and see if it helps with some basic concepts. I probably should have done an introduction to transistors first but I couldn’t help but jump right into it.
Again, thanks for the feedback. And hopefully some of the presentations will be informative and thought provoking.

[@Electronics4Guitar]

Sounds a lot like my experiences with Darlingtons back in the day as well. I always seemed to have better luck with Sziklais for whatever reason. Back in the 70s I would twist my dad’s arm to take me to a hamfest once a year and I’d try to find a good deal on power transistors, heat sinks, filter caps, etc.

[@darrenmurphy6251]

I think the bdx33/34 were low saturation voltage designed for switching only nothing linear, didn't know what that was at the time, I just used whatever I could get, most of what I made back then didn't work well!

[@darrenmurphy6251]

i when i was a kid with no money (early 90,s)i tried to use bdx33b and bdx34b as audio output , the bdx33/34 were plentiful from scrap barcrest fruit machine boards i was getting free, they use them to drive the lamp matrix ,they sounded really clear and livelly and werent oscillating but i could never control their thermal runaway. went to hitachi mosfets taken from dead disco / pa amps after that