750-90000 (-RT) Electric Speed Control for Brushless DC Motors

jharris1993

I recently purchased the Parallax Electric Speed Control [ESC] for Brushless DC Motors, P/N 750-90000-RT. Unfortunately, there is absolutely NO information about how to use, and wire, the device included.

So, I come to the Parallax site and look it up. Searching for the 750-90000 brought me to the "GemFan 30 A ESC" page. (http://www.parallax.com/product/750-90000)

Looking on that page tells me - essentially - what the product shelf package said - "For use with the ELEV-8 Quadcopter Kit". The retail packaging also mentioned that it could be used with "most RC equipment" and that it was "Compatible with a wide variety of 3.3v and 5v microcontrollers"

I have a few DC Brushless motor projects that I am working on, and this looked like something I could really use. However, there is absolutely no information about how to use it. No schematic, no datasheet, nothing that would tell me how to write a program - Parallax or otherwise - to effectively use it.

For example, it mentions under "features" that it contains a 5v Battery Eliminator Circuit. Further down the packaging says: "Cells: 2-3S LiPo Input". Are there actually batteries in this thing? (Of course, the motor it is designed to drive claims to have the same "cells".)

Likewise, all three of what I believe are the motor control wires are blue. So, which is phase 1, phase 2, and phase 3? Does it expect to drive a delta or wye motor? Or does it not really matter?

Can anyone direct me to more detailed information on how to use this fine product? If possible, could links to this information be provided on the GemFan 30 A ESC page?

Thanks again!

Jim (JR)

SRLM

This is a standard brushless ESC, similar to other offerings out there. I suspect that Parallax didn't include extensive documentation for two reasons:
1. It's standard off the shelf product
2. They don't manufacture it, only resell it.

To use it you give a standard 1000-2000uS PWM pulse every 20ms. The duration of the pulse corresponds to the speed of the motor. The 0 position may be at 1500uS or 1000uS (depends on the settings).

You should be able to find more information just by searching for brushless motors online.

The BEC (battery eliminating circuit) means that it has a 5v regulator onboard that will "eliminate" the electronics battery by regulating the motor battery to electronics voltage. This voltage is output on the 5v (red) wire of the 3 wire connector. There are no batteries in the ESC.

For a brushless motor it won't hurt the motor to connect the three wires in any order. If you notice that the motor is spinning the wrong way (from what you want) simply swap any two connections. It should work with any normal hobby brushless motor.

Duane Degn

I agree with Jim. There should be more documentation that what's provided.

There should be at least a sheet describing how to program the ESC (if it can be programmed).

Here's a similar ESC with instructions about programming. I don't know if they use the same programming protocol or not.

You might want to send Parallax support an email. Every interaction I've had with Parallax has been extremely positive. I'd likely be a fanboy even if they didn't have the Propeller chip (which won me over to fanboydom early on).

Many of your questions aren't Parallax's fault (though I agree there should be more information provided). Your questions just show you're very new to all this. In which case, you've come to the right place.

I'll attempt to answer some SRLM missed. No, it doesn't have any batteries of its own. The 2-3S means you can power it with either two or three LiPo cells in series (with freshly charged batteries this is between 8V and 12V).

I don't know about delta or wye motors.