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I have piles of junk ESCs that need to get fixed up.

Me too, what's your address and your turn around time

I don't think I comprehended half of what you just wrote, but it is cool that you can figure all this stuff out. I would have just cut my loss and tossed the bugger.

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I really enjoyed reading that! I was almost late for work beacause I was reading it

Makes me wonder why Demon on their proking used the same BUZZ11 fets but a TIP36A pnp power transistor for the brakes? It does seem more elegant to use a similar topography as your Tekin.
Could it be because of the reverse?

I just got done re wiring a Demon 2C from 1981 (pre FET)
BC249 npn power transitor FWD with telay bypass for full FWD. BC250 pnp power transitor for brakes and another relay for reverse.
Reminded me of that old school speed control you repaired in another thread.

That's crazy awesome that you can do all that. I think my fav older ESC is the Novak M5. Perfect for stock club racing.

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I see you still have original BUZ11 by Siemens!
These were the best ones by far, also the most expensive. I tested several brands BUZ11 and the Siemens always had lower on-resistance.

Regarding the Demon ESC, there is one reason why you don´t find FETs used for brakes or reverse. A traditional PNP transistor was not only cheaper but also much easier to use for this task. If you wanted to use a FET, you had to go for a N-channel FET as P-channel FET were not available or not ready for the amps needed. Using a N-channel FET means you need a drive signal what is much higher voltage than your battery voltage, as this FET also rides above that voltage. But a lot of people didn´t knew how to get such circuitry working so a lot of the early FET ESCs don´t use FET brake. It was not just Demon but also several other manufacturers. Also using a FET for this task was a risk as you had to use a really clean and well designed circuitry. I personally used a lot of time for developing a circuitry which worked perfectly. Some other ESC got wrong signals from forward section induced into brake section. This means both forward and brake transistors got an on-signal at the same time and resulting in a shorted output stage. Even when this signal was limited to a very short period, this will short the battery and create very high current draw burning the transistors or even then battery.

I discussed this with Nick (Demon) at some point but he never went this way. Late Demon ESCs might use FET-brakes but these were designed and manufacturered not by Nick.

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You know all of the early ESCs used a servo amplifier for doing the basic circuitry. Driving stages, BEC etc. are used additional. All of these are important and the way you design them but in my opinion the right servo controller made a large difference. Of course you still could tweak that integrated circuit to your needs and goals but I found exactly one of them working to my expections. Many years after I stopped making my own ESCs I found some of my favorite companies as Delta and Victor used exactly the same, I think Novak not. And the guys who designed this amplifier also were the first to make a commercial ESC.

The cross short could not happen just at brakes, actually more when forward drive is used you have to keep the brake section from being engaged. One reason is the servo amplifier, another one the driving stage and finally the FETs. A main problem also was the FET transistors are voltage controlled and there is no real current applied. So the FET could go to on-stage on it´s own, if any unwanted (induced) voltage is building up in the driving path. The Schmitt-Trigger won´t help you in this case.

It scares me how much you guys know

Well just about the old stuff, I have little to none knowledge on brushless ESC. Use them, but not more.

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hay tamiyadan do you fix brushed esc for people
or is that what you do on snow days for fun
i didnt know what you was talking about but
i am pretty sure you did fix it though
marty

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