SMALL - SMALL - Telemetry SMALL - Radio
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Old Sep 17, 2011, 09:45 PM
Scratch building addict
rotagen's Avatar
United States, CA, Felton
Joined Jan 2005
664 Posts
Frsky receiver not working with brushed motor

Don't know if anyone else has seen this. It doesn't make sense to me, maybe someone knows why. I dug out an old trainer plane of mine for a friend that is learning to fly. It has a brushed motor/brushed esc designed to handle lipos and I'm running with a small 2S lipo.

The old receiver was FM but I wanted to try my Frsky rx in it.

Well all channels worked except the esc/motor (ch3). I got proper servo movement but no response from the motor. Took me a long time as I figured it was the esc, then possibly the old brushed motor but swapping them out did nothing, no motor response.

Then went back to the old FM receiver and everything functioned.

Anyone know why? It seems crazy to me, the Rx should be giving the same signal to the esc, but maybe not ?
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Old Sep 17, 2011, 09:49 PM
I don't want to "Switch Now"
pmackenzie's Avatar
Toronto (Don Mills), Canada
Joined Dec 2002
17,381 Posts
Make sure the FrSky reciever is not in "High Speed" mode.
The LED should flash slowly if you turn on the receiver without turning on the transmitter. If it flashes quickly then press the bind button for 3 seconds to change modes.

(This assumes you are using a D8 telemetry receiver)

Pat MacKEnzie
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Old Sep 19, 2011, 01:22 AM
Sudden Freak
c2po's Avatar
Atlanta, GA
Joined Oct 2006
330 Posts
Originally Posted by rotagen View Post
Anyone know why? It seems crazy to me, the Rx should be giving the same signal to the esc, but maybe not ?
Probably because old FM receivers usually output 5V PWM signal, and FrSky receiver has 3.3V PWM output (as also many other modern receivers).
I bet your brushed ESC doesn't like it. Look here for more info.
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Old Sep 19, 2011, 06:05 PM
Suspended Account
Panorama City, CA
Joined Sep 2004
5,566 Posts
Old brushed ESC was probably made to match old FM receiver.

Just stay with old FM radio.

To fly with 2.4, change motor and ESC to modern brushless.
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