just got done building one of these:
http://www.hardforum.com/showthread...=npn+transistor
I used a 50kohm Liner Pot and NPN transistor MPS2222A(RadioShack Part)
(http://filebox.vt.edu/eng/ee/faculty/lai/mps2222.pdf)
My problem is.........
When ever I turn the pot to 7.00v to 5.00v I get an odd buzzing from my power supply, I opened my power supply to see if it was arching or something visable and found no clues as to what was making the noise. Has anyone ever heard of this before and if so what was making the noise?
Here's some more info.
Ok I went and hooked it all up and put a delta screemer(.48A) on it and.....(With 50kohm pot)
1. Using a Multimeter I checked voltages- I could change it from 0.00 to 11.43v
2.The NPN got hot with only 1 fan on it I would say about 120-130F(I'll check in the morning with my temp probe.)
I also used the 100kohm liner pot and got the exact results only when turning the nob it was more touchy(voltages increased/decreased more with the same amount of turn on the pot than the 50kohm).
O and here's how I hooked it up....
12V in to Pin 3(NPN) and middle leg of pot
Left leg of pot to Pin 2(NPN)(Nothing on right leg of pot)
Pin 1(NPN) to to fan
Should something be hooked to the other leg of the pot?
Thanks
Kook
http://www.hardforum.com/showthread...=npn+transistor
I used a 50kohm Liner Pot and NPN transistor MPS2222A(RadioShack Part)
(http://filebox.vt.edu/eng/ee/faculty/lai/mps2222.pdf)
My problem is.........
When ever I turn the pot to 7.00v to 5.00v I get an odd buzzing from my power supply, I opened my power supply to see if it was arching or something visable and found no clues as to what was making the noise. Has anyone ever heard of this before and if so what was making the noise?
Here's some more info.
Ok I went and hooked it all up and put a delta screemer(.48A) on it and.....(With 50kohm pot)
1. Using a Multimeter I checked voltages- I could change it from 0.00 to 11.43v
2.The NPN got hot with only 1 fan on it I would say about 120-130F(I'll check in the morning with my temp probe.)
I also used the 100kohm liner pot and got the exact results only when turning the nob it was more touchy(voltages increased/decreased more with the same amount of turn on the pot than the 50kohm).
O and here's how I hooked it up....
12V in to Pin 3(NPN) and middle leg of pot
Left leg of pot to Pin 2(NPN)(Nothing on right leg of pot)
Pin 1(NPN) to to fan
Should something be hooked to the other leg of the pot?
Thanks
Kook
Facebook
Twitter