Maintain current

[h2ocommuter]

not bad for a n00b, not bad at all. I double and triple checked your layout, everything is correct, except you have no power going to your lm339. Here's what it should look like...

Just to be clear here, your PCB layout is on top of the pcb, that is, you should mount and solder the parts right on the etched (top) part of the board according to your pcb layout. If you wanted to mount the parts on top of the board and solder underneath, like most hobbyists do, you will have to mirror the image.

I missed the Power on the 399 also I missed it on the original ridelong drawing.
I apriciate it.
I made a pcb layout visualizing it like ridelongs pic. show's.
I would like someone to check it out for me. e-mail.
I am building it using spades and I turned the pot upright too.
I figured it would go into a closed box when finished. set it and forget it.

[sp1r0]

So you got it working or what? We expect progress, heh.

[galkaen]

Hi Guys!

This is my latest layout of Ridelong's PWM Schematic.
If you are interested in the .PCB file email me (galkaen@gmail.com).
Ill be glad to share it.

[scratch1676]

h20commuter did you get your pwm working? I read the post and you made me laugh will all the trouble you had. I went thru the same stuff and it was living heck. you reminded me of myself.

[jeev_alexander]

Keith's Garage,

Make sure you have the correct schematic!

My first pencil drawing had a mistake on it. I have since fixed the pencil drawing, but the guy who drew it with a layout program never fixed his.

The mistake WILL MAKE THE FET OVERHEAT and probably toasted the fet. The fet will get only mildly warm at 14 amps with the listed heatsink and no fan if the circuit is operating correctly.

Here is the correct schematic:

www.mikecramer.com/images/ifeedpwm.jpg

Hi ridealong, Thanks 4 ur circuit,i made this circuit but there is no current limiting is happening...can you advice what could e the reason? The FET is getting warm mildly ,no pulse is getting generated from LM339,only deviation from ur spec is the resistor instead of .01 i put five .05 in parallel so the effective resisitance is .0125,guess its ok.

[galkaen]

Hi Ridelong,

Finally have the parts but couldn't get the right fet. Will it work with (ISL9N302AP3)?

TKS

Give me your email and i will send you my new pcb file.

[galkaen]

It would be nice if you return to this forum thread and help us build this thing.
I have tried 5 times to put it together but it just doesn't work. Please HELP!

I've been succesfull with ZFF PWM, which is a lot more complicated. But i'm willing to build your circuit because of its simplicity.

Again PLEASE HELP!

[ridelong]

Galkaen,

Sorry haven't been on this thread for a while.

The ISL9N302AP3 should work with a good sink.

I installed the temperature feedback unit designed September 2008 and have been using it since.

Russ