By: Tillmann (IP: 84.167.156.*)
Written on: 28-04-2005 12:38
Hi,
it's very strange that the thermistor burned out. That really shouldn't happen. It is normal for the transistor to get rather hot and in case of overload, it may burn out, but in no case that should happen to the thermistor. Are you sure you got the right pice? 10K (10000 Ohms) - not 10 Ohms or 100 Ohms or something?
Try again using the correct piece. Even with a 3.8W fan, nothing should burn out; the circuit can handle that kind of power. If the transistor gets very hot, you can add a heatsink it it, but I don't think it will be required.
bye,
Till |
By: tim (IP: 192.250.34.*)
Written on: 06-03-2006 14:36
I had the exact same problem when I attempted to use a radio shack 12v 1000mA power supply. I was only running 2 .08A fans. Thermistor went red hot and burnt up in about 1 min. |
By: Tillmann (IP: 146.140.7.*)
Written on: 06-03-2006 15:19
Hi,
with proper choice of components, it is not technically possible for the thermistor to overheat. At 12V, the maximum theoretical power dissipation of the thermistor is around 0.015W, and this will not cause any noticable heat.
If you accidentally used a 10 Ohm thermistor (as opposed to 10K Ohm), max power dissipation is around 15W, and of course the thermistor will burn down within seconds.
bye,
Tillmann |
|