Circuit which is also equipped with temperature sensors would protect the high temperature. However, in the above circuit which necessiatated the input of the amplifier / audio signal. The way it works is , if the amplifier circuit to work and ouput signal to be connected to this circuit , Fan 12V will work well. If the received audio signal this circuit does not exist , then the fan 12V die. And automatic circuit amplifier also not work and does not require refrigeration. Part List : R1_________________220K R2,R9,R10,12,13_____100K R3_________________2K4 R4_________________22K R5_________________1M R6_________________150R R7_________________2K2 R8_________________33R 4W R11________________10K C1_________________100pF C2_________________47uF 25V C3_________________100uF 25V D1,D2______________1N4148 Q1_________________MJE350 Q2_________________MPSA42 IC1________________7915 IC2________________LM35 F1_________________Fan 12 Volt