Discrete audio amplifier project PT4 current mirror

[@AbnerBerganza]

Cant believe someone is really explaining this in detail. Actually the whole internet theres is little info. Once I got to know enough I can realize the great value on ypur work. And you make it look simple

[@stephankashkarov1761]

The cat scared the crap out of me. Wasn't expecting that

[@ckimsey77]

A thousand thanks to you bro, this series is awesome!! I know moderately electronics, but still lacked that "ah ha" moment of the bigger picture Your vids have allowed me to understand how all this works as a whole and i much appreceiate the time you put in. Drawing out the schematics as small stages of the whole really makes understanding the system much easier, and you do an excellent job describing how it works in detail. Of all the vids by various people ive watched, zero compares to your level of explaination and clarity.

[@christheother9088]

I set this up and WOW that thermal runaway was pretty extreme in the first circuit. The degeneration Rs calmed everything down. We have a cat "Pickles" who is a black and white cat that looks similar to yours.

[@andymouse]

It's all comming back and I know Snickers is at peace....cheers.

[@reinermunch5159]

I like your explanation part by part or functional groups. It's easy to understand. And even when I don't need an amp it would be nice to build one. Snickers is so cute... a home without a cat is just a house

[@mikeyinhd]

Great Video, love the cat. I was going to add that if you are concerned about the transistors being unmatched, if you have a lot of a cheap transistor laying around (I have like 100 2N2222’s) you can test the base-emitter voltage on several and settle on a max allowed difference for you application. Typically for myself, I try to get Vbe to +/- a few mV. When I need a good current mirror, I usually scour parts vendors for pre-built current Mirror IC’s so I don’t have to worry as much about thermal coupling. They also typically use cool tricks like supply independent biasing/band gap references for temperature independent boarding. Thanks for the video! -Dave

[@mikeyinhd]

Temp independent biasing* please forgive all the typo’s. Ha

[@SciPunk215]

Thank you John. I like the theory and physics behind electronics, but this kind of practical application is most helpful.

[@bijouxbijouxbijoux]

Love the way you go through all this John, keep up the good work ! And that sneakers entrance was priceless ! ^^ Even made some kind of special sound effect on the microphone wich made it even more epic :D

[@electronicssciencebysherry5050]

Nice Mr.John keep it up for us de beginners.

[@nowt1002]

Great video and explanation. Really enjoying this series and looking forward to the next installment

[@charlesklein7232]

thank you for telling me about "DEOXIT" never knew it existed. but their are other grease that dont have grease in it. radio shack sells it but they dont exist.

[@rolfts5762]

John, you make very good and interesting videos. ( //btw: do often forget to respond with thumbs. Would guess all of us do when watching Y.T. clips ) have nice week. br, from norway

[@snaprollinpitts]

thanks John, looking good, I can't wait for the next video!!!

[@TAMIL-MUSIC]

please make a reviews of tda8950 tda8954 and 600w single powersupply 50v class d amp i forgot the number of the ic

[@rrangana11]

Thank you John... Good work...looking forward to you next video.

[@boonedockjourneyman7979]

There are 3 hour diatribes on KZbin that aren't as clear as this clean little demo. The bench does what PowerPoint can't. People should be aware when searching further that 50% of the stuff out there is about MOS die level issues in creating internal current references for IC masking so avoid that stuff if you want more in depth and mathematical treatments.

[@Dazzwidd]

this is great, but I don't trust those prototype boards, they're asking for intermittent/high resistance contact related issues. Other than that, very great viewing, love the investigative tinkering with the scope, meters etc. :)

[@terencekaye9948]

Hahaaah,, Fantastic John,, Been on the edge of my seat waiting for this one,, :) Sorry for the Tone stack question :(

[@CristinaKuo]

Great video! btw I love your cat

[@Stat1onary]

lmao that cat scared the shit out of me i dont know why

[@btouw8558]

interesting go on

[@Marco.SalaMessom]

Very good! Keep doing.

[@dibyamartandasamanta583]

Thanks for awesome tuts

[@RockOfGreece]

I shat my pants when the kitty got on the bench

[@gingernut3411]

Thank you for the brilliant content. I'm curious about your pre amplifier, is a home made one?

[@AniketBasak]

yea, he has a video on it.

[@BlankBrain]

Discrete audio amplifier project PART 1 kzbin.info/www/bejne/Zp6Wi6ecbd6phbs (Introduction) PART 2 kzbin.info/www/bejne/qF7aZGpshJ6MkKc (Supply voltage, Transistor SOA) PART 3 kzbin.info/www/bejne/q2rSoWB5d9GbrZI (Input stage)

[@BIGRIP87]

i love you man

[@bigbread9000000]

are you using matched transistors? if so did you buy them that way or how did you match them?

[@kevinbyrne4538]

It is possible to buy pairs of matched transistors: they're usually mounted on the same chip. However, it's also possible to use separate transistors of the same type (e.g., 2N2222's) and to put low-value resistors in the emitter-ground path in order to reduce any substantial differences between the transistors.

[@arjunpudu799]

Why without emitter resistor the current is increasing ?

[@lens3973]

Transistor is heating up. When a transistor gets hotter, it takes less voltage on the base to flow current through collector to emitter, meaning as it heats up, more and more current flows, meaning it heats up, and so on. The resistor limits the current through the transistor. As the current through the transistor increases, the current through the resistor increases. Resistors flow less current when they heat up, meaning it counter acts the thermal runaway of the transistor. Hope that helped

[@michaelrobert4094]

Nice cat! 🙂

[@ZipTiePros]

Hey John, love the videos by the way, I wanted to see if you or anyone here would help me figure something out. I have an old 4 channel car amplifier that I bought with only 2 channels working. I open it up to see what could be the issue and am greeted with missing mosfets; 5 to be exact. They were just blown to bits but the amp still turns on and plays music on that one output. (Two outputs by the way) I can replace the mosfets no prob, but the mosfets this thing has seem to be impossible to find. My question is if there is an equivalent I could use and if so must I replace all the mosfets? Thanks to anyone who helps. (Number on mosfets is SFP70N06)

[@ZipTiePros]

Also shows Ah 1311 on the mosfets. It's a Sundown Audio SAX 100.4 If anyone was wondering.

[@flurng]

Methinks SOMEbody would like to suggest you change the name of your channel to; "John&SnickersAudioTech".....

[@janmorgos5221]

Great videos John, but i think, that you should use more professional measurement tools :) no cheap Dmm from china

[@charlesklein7232]

your cats hungry or just lonely, do you let him go outside, or is he a house cat.

[@charlesklein7232]

the board can be rebuilt! the parts can be replaced! it comes apart. and they are really inexpensive, BUY A NEW ONE! the metal bends, their not made of quality! i wonder if you could buy quality metal parts for its inside?

[@charlesklein7232]

when you speak its difficult for me to follow because i have no education on this and consequently im a moron. but it appaers your not building the hole thing. i wanted to say is it a stereo of a 5.1 surround sound? but you seem to only be building part of the amp. im confused. maybe you should have a video on what your doing.