The home audio amplifiers such as subwoofer amplifier in our home audio system is usually powerful. The output of these amplifiers usually connected to a large power loudspeaker such as subwoofer. When we activates the power to the amplifier, the loudspeaker works with annoying "TTAP" sound and this will damage your loudspeaker. So this circuit keep the situation clear when you power up your home theater. It allows the sound to fade in to the speaker by activating a relay.
Monday, May 31, 2010
Friday, May 14, 2010
Hard Disk Temperature Controller
Many of us have had a problem of over heating computer hard disk while in long use. Here is a temperature controller circuit that switch on a DC fan to reduce temperature of your hard disk drive when it increases abnormally. The metal plate sown in the circuit should be screwed tightly with your hard disk to work it as a temperature sensor. When the temperature on hard disk increases than a preset level, the relay is activated and the fan connected to it will be start running to reduce the temperature.
Thursday, May 6, 2010
Low Cost Metal Detector Circuit
Metal detectors are usually very complicated and it may be consist of very costly components and metal detector DIY circuits are rare. However this metal detector hobby circuit can be constructed by only a few components such as BC548 and an ordinary AM radio that we usually use.
Wednesday, May 5, 2010
Burglar Alarm System With High Sensitivity
Most standard light sensors that used in ordinary burglar alarm systems requires precise alignment of light beam to deactivate the alarm system during standby mode. However this circuit of burglar alarm is so sensitive that it will detect a moving person at a distance of few meters in pure daylight or under electric lighting.It requires virtually no set up, and may be simply placed within the line-of-sight of almost any light source including ambient daylight or high end fluorescent electric light. The alarm system uses a beep generated from the circuit driven through a buzzer that is high enough to detect the entry of a person inside the fence.
