Mosfet Equivalent Parts

[bryan]

Hello:

Was going to breadboard this schematic below, but don't have the correct Mosfets, and nothing available local. What should I be looking at when trying to substitute something equivalent. Other than the obvious such as rated the same or higher in the following categories:
Correct Polarity:
Continuous Drain Current Id:
Drain Source Voltage Vds:

Is there anything else in the specs of a MOSFET I would need to match.

Just a note, does Q1 need to be a high current as I have a 2N7000 handy. From the schematic it would only switch the fan off

https://www.discovercircuits.com/images/2012/12V%20Cooling%20Fan%20Thermostat.pdf

 

[dougy83]

Just a note, does Q1 need to be a high current as I have a 2N7000 handy. From the schematic it would only switch the fan off

Q1 doesn't have to be anything special and 2n7000 should be fine. It is providing positive feedback, and thus creating hysteresis (this means that the temperature that the fan turns on is different to the temperature at which it turns off).

 

[bryan]

Thanks for that, anything I need to look for that's critical in a equivelant for Q2 other than the ID and Vds

 

[dougy83]

Just make sure it's a P-channel MOSFET too...