Graupner Reservoir Capacitor

[OldPrairieRedNeck]

Yes that would seem reasonable. It's been a while for me too but somewhere in the back of my mind I seem to recall that caps were different. That is how capacitor discharge ignition systems work? Maybe they charge them in parallel and discharge them in series. Hmm... need to research that!

[tkbig]

If you look up cd ignitions they all have an ignition coil of some sort and that is where the high voltage comes from. I suspect these capacitors were initially inserted to protect the receiver from high frequency noise produced by the motor or the esc. An added benefit would be to smooth out any relatively high frequency voltage spikes generated by the higher draw servos we use today. At least that's my theory and I'm sticking to it! Lol

Merry Christmas everyone!!!

[Pete]

I’m going to add a little to the subject may or may not be related. On some of my planes that I don’t have telemetry I install a digital voltmeter for monitor purposes on preflight. I notice that when I move one of the control surface (battery not hooked up yet) that the voltmeter would light up 00.0V & the red light in the receiver as well. So today I thought why not put a sensitive voltmeter on & by moving the elevator rapidly was able to generate 5.01V. Then I left the servo idle for an hour & still had a reading of stored energy at .74V. If I continued to leave the probes on can bring it down to .00V in about a minute. So I wonder is it possible depending on speed of the movement to produce more volts then what is being used times 4 servos (more on larger planes). By the way my body has constant reading of .20V.

Pete

[OldPrairieRedNeck]

Yes it's true, a cap cannot produce a voltage higher than the source charging it. Maybe I was thinking of current, but that is going to be limited by the circuit resistance so there is no reason these capacitors won't work. So ignore my warning please.

Peter, any motor with magnets in it will generate power when turned. I suspect the voltage you are reading after the servo has stopped is stored energy and is likely coming from a capacitor in the servo circuitry somewhere. I highly doubt that there is much being generated when the system is in use else it would be self sustaining and would be attempting to recharge the on board battery.

Man, I bet an electrical engineer would get a kick out of our attempts to understand this stuff!

[JBajkor]

Man, I bet an electrical engineer would get a kick out of our attempts to understand this stuff!

There is nothing special about a cap bought from a hobby store. If you can solder a servo wire, go to Digikey, Sayal, or any electronics supplier and buy a low ESR capacitor. Just make sure to get the polarity correct.
Joe

[JoeT]

Hahaha ever connect an electolytic capacitor in reverse polarity! !! It's hilarious.

Kabooooom!!

[itizme]

WiRe one end to the floor mat and the other to the door knob.

[Pete]

Hahaha ever connect an electolytic capacitor in reverse polarity! !! It's hilarious.

Kabooooom!!

The sudden heat should take the wrinkles out of the covering if any left!

Pete

[JoeT]

Back in my "MUCH YOUNGER DAYS" I used to install audio systems in cars for my friends. I accidentally installed a noise filter (Capacitor), reversed, and that's when I learned how much fun these things could be. hahahha

The sudden heat should take the wrinkles out of the covering if any left!

Pete