I have put the schematics and photos of an inexpensive and lightweight DC motor speed controller with 4 transistors and power fet to:

http://lennokki.innoplaza.net

Hello Bruce,

I see you have very interesting and advanced ESC circuit and PPM decoder on your page http://homepages.paradise.net.nz/bha...ectronics.html

That is how I would make them if I were sharp enough with microcontrollers...

Regards,

- Juha -

This speed control was made using the above 4-transistor schematic as the first independent electronic building project of a junior builder.

He made it without any model of component layout. The result is a 'matchbox' type controller. Lightweight, works well and parts did not cost anything - congratulations for the builder!

I've done "matchbox" circuits before and found that conservative amounts of goop or heat-glue can really firm it up. The weight penalty is minimal (less than the box).

Pullin'

ya i have just started in the rc thing and i am doing a school project i was wondering if you would make an esc from scratch if you have been doing this for about 4 months now? cuz it looks hard

Added to this brushed controller designs compilation:
http://www.rcgroups.com/forums/showthread.php?t=190829

Vriendelijke groeten Ron
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• int. E fly-in & diy outrunner meet, Aug.26 2007, Nijmegen, the Netherlands

Hmm It relies on a fixed PRF for accuracy...which you don't always get on a tranny.

Still a brave effort, and something that COULD be adapted rather nicely for ultra small motors on single LIPO cells.

whats PRF
pulse repetition frequency ????

Originally Posted by brucej

whats PRF
pulse repetition frequency ????

This is a low frequency ESC. It uses the same pulse frequency as the RC transmitter, which is about 30 ... 50 Hz.

The low frequency PWM tends to tremble smallest brushed motors like the GWS Pico motor, but 350 class and bigger motors run quite smooth with it thanks to their bigger rotating mass.

High pulse freq ESC's are easier to make with microcontrollers.

Originally Posted by vintage1

Hmm It relies on a fixed PRF for accuracy...which you don't always get on a tranny.

Still a brave effort, and something that COULD be adapted rather nicely for ultra small motors on single LIPO cells.

You are correct, this really is no accuracy circuit, but it runs nice once trimmed it to used transmitter. 2 channel tx's have a little higher pulse rep freq than 6 ch tx's, for instance, so I must trim the esc a bit if I change to a different tx. But it has worked quite well and it really is lightweight.

Recently, I have got nice tiny Atmel's AT90LS2343 chips, which seem need practically no extra components to read servo pulse and drive the power mosfet of a high freq ESC. So, it could make a still lighter ESC for microflyers than this 4 tranny one..!

Alas, I have no experience of making programs to microcontrollers. Anybody give a beginner advice how to make the 2343 measure servo pulse width and save it as a variable for calculating PWM output..?


- Juha -

Juha,

You might find the DIY (Do It Yourself) forum here interesting and a good place to find the answer to your question:

http://www.rcgroups.com/diy-electronics-199/

In fact, I'm sure the people over there would find your project interesting and they could also provide you with an interesting discussion about it.

You might want to post the same thing there.

Jack

Originally Posted by J. Hartikka

I have put the schematics and photos of an inexpensive and lightweight DC motor speed controller with 4 transistors and power fet to:

http://lennokki.innoplaza.net

i build the controller but an getting direct power to the motor even when switching the power off please help

dd
south africa

Hi DD!

Your power fet obviously keeps conducting when it is not supposed to.

Check:

- Mosfet polarity. If source and drain are reversed it will conduct all the time.

- Mosfet gate voltage? If it has zero volts, it should not conduct. If 2 ... 5 volts it should conduct and power up the motor.

What?
Without pcb?

Sure, unnecessary parts are left out..! Leaving the heaviest part out of the circuit - the circuit board. This cuts the circuit weight to less than half. This is of course desirable for featherweight flying models.

The electricity does not mind the missing PCB. It flows directly from one component contact to another quite as well as with the PC board acting as intermediary.

If the weight of the circuit is not critical using a PC board will of course make the circuit more rugged.