Have you been keeping up with Zero on youtube? He is on version 2 of this PWM. It is looking really good so far.

http://alt-nrg.org/pwm-v2.html

colchiro Wrote:Try this one: http://zerofossilfuel.googlepages.com/pwm.html

I like the idea that it's current limited, (which is more important than adjusting the freq IMO).

Do these just limit amps or do they send a higher voltage signal also

Where can I buy a good reliable PWM ? I want prebuilt with instructions. I don't think I can build ZFF's unit.

glbart Wrote:Where can I buy a good reliable PWM ? I want prebuilt with instructions. I don't think I can build ZFF's unit.

PWMPOWER.COM builds custom pwm's up to 100amps

cbkid Wrote:

colchiro Wrote:Tony, I'd check with ZFF himself before starting this project. Someone may already have a board (or preassembled unit) in the works.

Hydrogen garage sells a pulse width mudulater kit for $22.00 I includes all of the parts and circut board.
CBKID

I bought one of theirs and assembled it very carefully, it didnt work and I discovered it had a defective board. Recommend people watch ebay for awhile. automatic current sensing/limiting pwms are coming!

Zero's PWM is really nice. I am working on a feedback loop for current sensing, but instead of using speaker wire for a shunt, I am going to use one of microohm.com's current shunts, the sp625 I believe. They have <.001 ohm shunts. The shunts have two leads on each end to reduce resistance in the leads. Once I figure out AutoScetch I will post my schematic.
Bill