P
Pete
- Jan 1, 1970
- 0
Hi, I'm not sure whether anyone can help with this problem but I though
I would post on the of chance because I haven't a clue. I have made a 12
V speed controller/light dimmer circuit that came in kit form. It uses a
LMC555/7555 CMOS timer and BUZ71A power mosfet transistor. A 10K pot
controls the motor speed. I was testing the circuit tonight and it
worked flawlessly then suddenly the pot stopped controlling the speed.
It now operates at full current irrespective of where I set the pot. The
pot seems to work alright tested with a multimeter, so I'm anticipating
the problem is elsewhere. The transistor gets very hot (it has a heat
sink connected) as does a big 3A diode. There are no obvious signs that
anything has blown at all. Any clues?
Pete
I would post on the of chance because I haven't a clue. I have made a 12
V speed controller/light dimmer circuit that came in kit form. It uses a
LMC555/7555 CMOS timer and BUZ71A power mosfet transistor. A 10K pot
controls the motor speed. I was testing the circuit tonight and it
worked flawlessly then suddenly the pot stopped controlling the speed.
It now operates at full current irrespective of where I set the pot. The
pot seems to work alright tested with a multimeter, so I'm anticipating
the problem is elsewhere. The transistor gets very hot (it has a heat
sink connected) as does a big 3A diode. There are no obvious signs that
anything has blown at all. Any clues?
Pete