Subject: Mosfet for temperature control.
By: obedey (IP: 220.245.178.*)
Written on: 27-08-2005 05:47

I've been having trouble finding a mosfet to build a temperature control. I'm going to build it at school. They order from this company called electus. Originally i was going to use the MTP3055E 12A 60V Power Mosfet but when we ordered they said they no longer carry that part. So ive been looking at this BUZ-71 Sipmos Power FET. They have a pdf on it here
thats says it is a 14A, 50V, 0.100 Ohm, N-Channel Power
MOSFET. Do you think that sounds like the part i need??

By: obedey (IP: 220.245.178.*)
Written on: 27-08-2005 05:53

sorry about double post but does anyone know where I can find like a dummies guide to MOSFETs. Id like to learn how they work.
By: Tillmann (IP: 172.179.44.*)
Written on: 27-08-2005 12:14


probably the part you mentioned will work. Any N-channel MOSFET will work, as long as it's powerful enough (this part is) and it's not some exotic part (e.g. depletion type).

Understanding MOSFETs is a complex issue. I recommend this link:
The first sentence in the introduction is a good simple summary about what a MOSFET is:

"The Field Effect Transistor is a device which enables us to use one electrical signal to control another."

This is exactly what we're doing in the temperature control circuit.

For a more in-depth view, I recommend the book "Microelectronic Circuit Design" by Richard C. Jaeger.

By: obedey (IP: 220.245.178.*)
Written on: 28-08-2005 01:28

thankyou for your help, that article was a lot easier to understand than the ones i was finding.
By: Carl Wong (IP: 71.106.186.*)
Written on: 10-10-2005 22:07

I have just built a temperature control as instructed on the website and I am testing it on the fan for my hard drive.

How does the temperature control work, exactly? Is it designed to maintain a specific temperature, the way a thermostat does, or is it designed to supply a higher voltage to the fan as the temperature goes up, so there is a increasing correlation between temperature and voltage?

Also, could circuitry be added so that the fan will always spin at a minimum speed that you select, and increase speed only when it goes over a set temperature?

Would there be a way to change the sensitivity of the device adding or changing components?
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