Will an ESC respond to analog DC? You know that PWM is pulse width modulation... which means the higher the PWM value the more high pulses per second.... ACTUALLY: a longer "high pulse" duration in every given cycle, but for our discussion; pulses/sec is "good enough". I assume then you know that a ESC sends PWM commands to a motor. A motor is too slow to respond to start / stop / start because of its rotational mass. Therefore, more high pulses raises the average voltage the motor "reads" therefore increasing the motor's speed. (Don't believe me? Use a Multimeter (simulates the motor) & a O-Scope (views the circuit) to read a PWM signal at the same time.) ---- IN ANY CASE ---- My question is: Would the ESC work the same way? Would it read the "average value" being sent by the reciever or would it "lock on" to the pulse cycle & read the pulse width directly? The application is the pump. If we use a ESC to control the pump we can adjust the flow rate (important for big gun)... but at the loss of a channel. UNLESS ESCs read the "average", in which case, we can use a potentiometer to "throttle" the pump.
I don't think so. They generally are smarter than that. You could probably substitute a PIC for the ESC and program it to throttle down with a potentiometer. Or you could probably use ATV on your transmitter's gear switch to turn down the output.
If you look around, there are servo testers (at least there used to be) that basically consisted of a pot and a few chips to produce the correct signal for use testing servos.
I know that Brian Koehler found something on the web, because he's using it to play with a shore battery using the circuit with a hardline saves a freq for a boat It's fun to let some of the younger members give it a shot, since it's limited to about 45 degrees of sweep, and they don't have to manuever it.
Besides servo testers, or just programming a $3 Picaxe chip to give the radio pulse for pump speed you want (using the servo command), http://www.dimensionengineering.com/SyRen10.htm has ESC's that offer analog speed control (not as cheap as an aircraft ESC and picaxe chip). Cheers,
I use the R/C version of these but buy them from Trossen robotics, they are cheaper. So far no problems, just not waterproof, so its in my W/P box. http://www.trossenrobotics.com/store/p/5104-Sabertooth-dual-5A-motor-driver-for-R-C.aspx
Having pondered for a while, the cheapest, and perhaps simplest, solution would be the Picaxe 08M chip to send the servo command. The total program would be "servo 1, 150" for middle speed. If your ESC needs an -0- throttle to arm, that could, of course be programmed in as well. Something like: "servo 1, 100" - to arm "Pause 1000" - gives the ESC time to sense the arm "servo 1, 150" - sets the ESC to mid speed. Number between 100 & 200 No pot needed. A 3 pin serial connection would let you program it on the bench, and field adjust it in firmware to make it pretty bulletproof. Total components - one 08M, 3 resistors, two 3 pin headers. Might want a couple of filter caps. There is a board designed to control 3 servos with the 08M available for about $15 that could easily be pressed into service if you don't want to figure out the wiring/filtration/etc. yourself. You can even use one of the servo "outs" as an input that lets you control the pump from your radio. One reason for going this route is that, as a pot gets wet, the value will change, perhaps making your "tuned pump" erratic. Cheers,
