Re: PWM speed controllers cheaper than Victors?
 

If you're interested, and you have the PCB artwork in Gerber format, you can upload it to the folks over at BatchPCB (which is run by the guys at SparkFun) and they'll make it available for ordering on demand.

Matt

Re: PWM speed controllers cheaper than Victors?
 

OK Folks, procrastination time is over.

This circuit is based on the "Test Circuit" on Page 5 of the LMD18201 Datasheet. You need to study the data sheet to figure out the input signals.

This is an H-Bridge. It does not decode R/C PWM signals such as used by Victors and Jaguars. Instead it takes a variable duty-cycle 'PWM' signal and amplifies it. There are several ways to convert R/C PWM to a duty cycle, including single-chip solutions.

The PC Board is simple enough to reproduce at home with stick-on tape. The set of 3 holes between IN+ and GND is for the 1200 uF capacitor; the extra hole allows for some component flexibility. The other 2 holes are for the 1 uF cap. Near the logic input side, the 2 sets of holes are for the 10 nF caps between pins 1 & 2 and 10 & 11. Pin 1 of the LMD18201 is marked with a square pad. You are looking at the COPPER side of the board!

You MUST use a heat sink with this chip, I suggest one about 2 or 3 inches tall and 1.5" wide, with fins, like this (but you can find these cheaper)

You are well advised to also coat the thick power traces with a layer of solder, to increase the thickness and therefore current-carrying capacity. Not mandatory, but cheap insurance.

The image is about to scale - the board should be 2.5" long and 1.125 wide - but use the logic input pin holes (spaced exactly 0.100") as a reference.

Any questions, let me know.