Can you check a radio control controller (for a hobby car or plane) is working by using a oscilloscope?
Answer:
You should be able to connect the antenna to a decent scope to see the output signal. The ground to connect would be the chassis ground on the transmitter, I'd expect.
DO NOT DO THE TESTING ANYWHERE NEAR AN RC FLYING FIELD! Presumably the reason you want to test the transmitter with an oscilloscope is because the servos are not reacting, and you want to isolate the fault. Since standard procedure for R/C vehicles is to switch on the receiver FIRST to ensure the frequency is not already in use, and you are not certain the receiver is functioning, then imagine if the defect's in the receiver and the frequency IS is use — you could easily destroy someone's beautiful plane, or injure someone by jamming a plane's control signal, without realizing anything is amiss.
You may be able to unscrew the antenna from the transmitter body, which will pretty much eliminate RF transmissions and may be a good idea during bench-tests.
i would have thought you would use a geiger counter or something to detect a radio frequency... i dont know for sure, i wasnt too good at physics...
If you can get the unit open you should be able to clip the o-scope to the antenna lead and a suitable ground and see if the unit is transmitting. You'll need a scope with a 100-MHz or more bandwidth, but that's pretty low by today's standards.
It will probably depend on what sort of modulation the transmitter is using, if AM it will probably work pretty well, but if FM it may be very hard, if even possible to see the signal on a general purpose 'scope. Keep in mind you are looking for the the modulation which is probably in the kilohertz range not the 27mHz, 72mHz or whatever carrier frequency. I'm not so sure a ground connection is actually necessary, but the negative battery terminal might be a place to try. Note that you scope bandwidth does not actually have to be as high as the carrier frequency, while the gain will roll off, an analog 'scope will still have some response well above the rated frequency and you are not doing quantitative measurements. I suspect a digital 'scope will probably have sharp cutoff input filtering, so you might need a high bandwidth, but if the transmitter is AM and you happen to have a demodulator probe, you are, again, only looking for the relatively low frequency modulation.
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