Im looking at an example of a DC fan circuit that regulates voltage according to temperature. Its an online example that i have modified slightly.
R1 is a 10k thermistor.
Q1 and Q2 are NPN and PNP transistors.
Id like to modify the circuit so that the fan will only come on when at least 3v is present. The fan is not shown on the diagram but i would put in it parallel with R7/D2. The fans I have have a minimum operating voltage of 6v and so running them at anything less will probably stall them.
thus if the output is less than 3 volts then the output should be 0
if the output is >=3 then the output passed should be 6
else the output should be passed unadjusted.
any help is appreciated.
R1 is a 10k thermistor.
Q1 and Q2 are NPN and PNP transistors.
Id like to modify the circuit so that the fan will only come on when at least 3v is present. The fan is not shown on the diagram but i would put in it parallel with R7/D2. The fans I have have a minimum operating voltage of 6v and so running them at anything less will probably stall them.
thus if the output is less than 3 volts then the output should be 0
if the output is >=3 then the output passed should be 6
else the output should be passed unadjusted.
any help is appreciated.
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