ramses

Hi, I have 2 questions related with ESCs.

1.) I have 30A Emax ESC. I want to connect it to DC power supply instead of li-po battery. If I set the desired voltage and max current from DC power supply, is there any problem? Motor max current 15A and ESC max 30A. Please share important points with me.

2.) I will send PWM signal from controller instead of PPM(that is generated via RC controller). Do I have to any other setting to drive motor on ESC?

CHELLIE

1. As long as you have sufficient voltage and Amp output from your DC power supply there should be no problems, I would think that if your DC power supply is able to deliver at least 20 amps, you should have no problem, the esc and motor dont care where the voltage is coming from, as long as there is enough dc voltage and amps, you should be fine.

2. If i read your second question right, it sounds like your talking about using a servo controller to operate the esc and motor, That should work fine . the esc is just looking for a signal to make it work. or you can use your transmitter and receiver to generate a esc / motor signal. the servo controller should only see about 5 to 6 volts input no more than that, or you may burn up your esc.

crxmanpat

Also be sure your DC power supply does not provide more voltage than your ESC can handle. Not sure if that ESC is only good to 12v, or 18v.

ramses

Thanks for your feedback
2.) I will generate PWM on Beaglebone(of course it doesn't matter any microcontroller can be) instead of using RC transmitter. I wonder that: is there any restriction on ESCs against PWM signal that generated by microcontroller?

kyleservicetech

Nope, done that myself several times with Microchip "PicChips".

You need to send a repeating pulse to your servo, with pulse width from 1.0 to 2.0 milliseconds. And, repeat the pulse every 20 milliseconds or so.

As far as using the PWM feature available on the PicChips, I found just used a variable pulsewidth by a simple 1 - 2 ms time delay for the "On" pulse, and a second 20 ms time delay for the "Off" pulse.

Most recent project was to use a PicChip timer to operate a servo, once per minute going to full clockwise, then return to counter clockwise. The software just output a 2 MS pulse, about 50 times, then output a 1 Ms pulse 3000 times. Simple, and it worked.

At least with the PicChips, using their PWM feature didn't have the resolution I could get with the simple time delay pulse generator program.

The arm on that servo pushed the shutter button on my Canon SX20IS camera.

CHELLIE

I am not aware if there is any restrictions on ESC against PWS signals, maybe one of the electronic Gurus here can chime in. if you have any issues in generating a signal with your microcontroller, here is a servo tester dedicated for rc use.

http://www.ebay.com/itm/New-Turnigy-...3D171373022360

kyleservicetech

Hi Chellie

That looks good, and should do the job.

But, my PicChip cost 99 cents, and can be programmed to do many things automatically.

With an evenings worth of programming anyhow

I made a couple of them for fellow club members that wanted to fly electric control line models. It was programmed to "first blip the motor" as a warning, then 10 seconds later, quickly ramp up to full power. Then run for exactly 4 minutes, then again blip motor power in flight, then cut power 15 seconds later. Wouldn't take much to include computer type jumper clips to allow digital changes in time for full power, increasing by one second increments to 6 minutes or so. No one has asked for it yet.

The entire circuit consisted of one PicChip, one resistor. That's it. (The resistor is needed for on circuit board reprogramming)

CHELLIE

There are cheaper servo testers out there, but you get what you pay for IMHO I have had great luck with turnigy products, so i tend to try to stick with them, Take care and have fun, Chellie