CASE # 55: Gary Liked to Pump Up the Volume
By Design News Staff -- Design News, April 9, 2006
Ever turned on your car stereo and BOOM! the woofers unexpectedly jumped out for one filling-loosening bass note? Just great, you've just been diagnosed with turn-on thump — either due to an amp that never had a muting circuit or one that's failed open circuit. Either way, OUCH! To fix this problem, Gary built a circuit that connects externally to any car audio amplifier and keeps his speakers completely disconnected from his amplifier until it's been completely powered up. Plus, it also works with a mis-matched set of amplifiers.
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For Gary Reck's complete instructions to build a customizable audio amplifier muting circuit, click here.
| Customizable Audio Amplifier Muting Circuit Parts List | ||
|---|---|---|
| Amt | Part Description | Allied Part # |
| 1 | Darlington Driver Array | 248-2007 |
| 1 | Single Supply Quad Comparator | 568-4666 |
| 1 | General Purpose Diode | 568-0144 |
| 1 | Capacitor 47 uF, 25V, 20 percent | 852-7078 |
| 1 | Resistor 10K | 895-0355 |
| 1 | Resistor 38.3K | 895-1159 |
| 1 | Resistor 7.5K | 895-0833 |
| 1 | Resistor 1M | 895-1141 |
| 1 | Resistor 681K | 895-1108 |
| 1 | Relay, SPDT, 12V dc Coil, 15A Contacts | 850-0205 |
| 1 | Relay, DPDT, 12V dc Coil, 15A Contacts | 850-0410 |
| 1 | Fuse 5A, PCB Mount | 846-2014 |
| 1 | Fuse .125A, PCB Mount | 846-2002 |
| Additional parts required: For a list of optional parts, go to http://rbi.ims.ca/4919-505. | ||
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