|Power Amplifier Protector Circuits|
Tuesday, April 03, 2012
Power Amplifier Protector
Now you can protect your HiFi amplifier from damage due to overheating. This circuit will cut off power to the amplifier board at the time the temperature was high. Automatically connect the power when the temperature returns to normal. This circuit uses a sensor NTC Thermister heat and also has a warning sound and reset determination.
Amplifier circuit protector is using popular timer IC NE 555 as the temperature controlled switch. The trigger pin 2 is connected to a potential divider consisting Thermister VR and NTC. Thus the voltage on pin 2 depending on the resilience and determination Thermister VR. NTC (Negative Temperature Coefficient) Thermister has a high resistance in the normal temperature and the resistance decreases as temperature increases. Threshold pin 6 of IC is used to reset the IC if necessary. When the pin 6 voltage gets higher than the IC pin 2 will reset and the output is low.
Power to the amplifier board is given by (NC) contact is usually connected from the relay and the switch S2. So that power to the amplifier board will be available through the NC contacts of the relay when the relay S2 and the state is not powered. Thermister resistance is governed by VR triggering pin 2 of IC peaks at normal temperatures. When the temperature inside the cabinet amplifier increases, resistance decreases so that it becomes conductive Thermister. This makes the trigger pin 2 of IC is low and its output is high. T1 works so that the relay energizes and the ringing of a bell. This will damage the electrical supply to the amplifier board. Relay will not be automatically powered when the temperature returns to normal.
Amplifier circuit protectors are very useful to protect your home sound system.
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