Search found 11 matches

by Jesse
Wed Aug 31, 2005 6:11 pm
Forum: General Discussion
Topic: PWM motor circuit and diode
Replies: 31
Views: 6060

Re: PWM motor circuit and diode

Thanks Joe. The diodes I'm using, now that I look at them, are "general purpose" rectifier diodes (these particular ones are from Radio Shack). Usually I get my stuff from Digi-Key or others, but I didn't have any on hand large enough, so had to make due. I do have some fast recovery diodes on their...
by Jesse
Wed Aug 31, 2005 5:59 pm
Forum: General Discussion
Topic: PWM motor circuit and diode
Replies: 31
Views: 6060

Re: PWM motor circuit and diode

By the way, I hope all of this will lead of to my simple problem of a HOT diode, and being able to use a more "normal" size one. Worse case: I'll just heatsink a TO-220 package diode.<p>I have a darlington array that I'm going to experiment with now with PWM. Should be able to switch fast enough. We...
by Jesse
Wed Aug 31, 2005 5:47 pm
Forum: General Discussion
Topic: PWM motor circuit and diode
Replies: 31
Views: 6060

Re: PWM motor circuit and diode

Thanks guys, your electronics experience is certainly appreciated.<p>Jesse
by Jesse
Wed Aug 31, 2005 4:22 pm
Forum: General Discussion
Topic: PWM motor circuit and diode
Replies: 31
Views: 6060

Re: PWM motor circuit and diode

Chris,<p>Isn't that the same thing the transistor could do? I'm going to dig some of those out first and give 'em a try, as positronicle suggested.<p>I've also ordered a few of those high-power TO-220 package diodes to play with. At least with them I can heat-sink.<p>Thanks once again!<p>Jesse
by Jesse
Wed Aug 31, 2005 2:40 pm
Forum: General Discussion
Topic: PWM motor circuit and diode
Replies: 31
Views: 6060

Re: PWM motor circuit and diode

Ron,<p>Thank you for the reply. You seem to disagree with what has been said. Do you have any suggestions?
by Jesse
Tue Aug 30, 2005 9:21 pm
Forum: General Discussion
Topic: PWM motor circuit and diode
Replies: 31
Views: 6060

Re: PWM motor circuit and diode

Great suggestion, I'll give it a shot after work tomorrow, getting kinda late now to play. I will deffinitly post back my results. With your ultra clear explination, I don't think I can go wrong. :-)<p>Jesse
by Jesse
Tue Aug 30, 2005 8:10 pm
Forum: General Discussion
Topic: PWM motor circuit and diode
Replies: 31
Views: 6060

Re: PWM motor circuit and diode

I'll go check it out. Just FYI, I'm using a IRL3103 mosfet. Is there a simple transistor circuit I could use to increase the power to the gate? Thanks again!<p>Jesse
by Jesse
Tue Aug 30, 2005 7:21 pm
Forum: General Discussion
Topic: PWM motor circuit and diode
Replies: 31
Views: 6060

Re: PWM motor circuit and diode

Yep, 80khz. :-) Whoops, big difference! However it's down to 26khz now with a period of 750. Sorry about that.<p>Thanks!<p>Jesse
by Jesse
Tue Aug 30, 2005 7:15 pm
Forum: General Discussion
Topic: PWM motor circuit and diode
Replies: 31
Views: 6060

Re: PWM motor circuit and diode

Alright, crude but hopefully effective, here's a quick drawing of the motor control part of my circuit, including MOSFET & motor. My freq. is around 26khz right now, and I can drop it more if recomended.<p>PWM Motor<p>Jesse
by Jesse
Tue Aug 30, 2005 6:45 pm
Forum: General Discussion
Topic: PWM motor circuit and diode
Replies: 31
Views: 6060

Re: PWM motor circuit and diode

Hi Chris,<p>Thanks for the quick reply. I had figured in the inductive load and "generator" effect, hence the diode. From what I had read, it sounded like if you get a diode rated for the same current as the motor, you should be fine. But as you said, I may need yet a larger diode w/ heatsink. Makes...
by Jesse
Tue Aug 30, 2005 6:05 pm
Forum: General Discussion
Topic: PWM motor circuit and diode
Replies: 31
Views: 6060

PWM motor circuit and diode

Hey guys,<p>I've come to the "experts" for some advice. Let me first quickly describe my project & circuit. I'm controling the speed of a 12v fuel pump via pwm. I'm using a microcontroller, 16F876, to output a pwm signal (using a period of 250, or about 80Mhz) to a high-power MOSFET.<p>My question i...