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<blockquote data-quote="thylantyr" data-source="post: 1539564" data-attributes="member: 560358">I was under the assumption that the detector could be a permanent install //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gifLED near dash to monitor the amp.The relay idea is actually more complex than the comparator idea. Comparatorsare simple, look here;Op Amps as Comparators section<a href="http://www.bcae1.com/opamp.htm" target="_blank">http://www.bcae1.com/opamp.htm</a>Both resistors, 1000 ohm form a voltage divider at the + input. This is yourreference voltage, any voltage you want really. Assume 12v battery as shown inthe picture, 6v is the reference based on those two 1000 ohm resistors.The capacitor connects to the &#039; - &#039; input, the 8200 ohm resistors is notconnected to the battery until you &#039;press that button&#039; on screen, so thevoltage at the &#039; - &#039; input is zero. When the cap charges and exceedsreference {6v}, the LED is lit up.To make a peak detector for this application, you don&#039;t want a capacitorbecause it will slow down the reaction time. You add a potentiometerto the + input to preset a reference, you scale the voltage divider so theopamp can accept high voltage from the amplifier so it won&#039;t blow up,and to be clever, add a zener diode to make your circuit immune to9v battery voltage fluctuations. A few more things to add.</blockquote>

[QUOTE="thylantyr, post: 1539564, member: 560358"] I was under the assumption that the detector could be a permanent install [IMG]//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif[/IMG] LED near dash to monitor the amp. The relay idea is actually more complex than the comparator idea. Comparators are simple, look here; Op Amps as Comparators section [URL="http://www.bcae1.com/opamp.htm"]http://www.bcae1.com/opamp.htm[/URL] Both resistors, 1000 ohm form a voltage divider at the + input. This is your reference voltage, any voltage you want really. Assume 12v battery as shown in the picture, 6v is the reference based on those two 1000 ohm resistors. The capacitor connects to the ' - ' input, the 8200 ohm resistors is not connected to the battery until you 'press that button' on screen, so the voltage at the ' - ' input is zero. When the cap charges and exceeds reference {6v}, the LED is lit up. To make a peak detector for this application, you don't want a capacitor because it will slow down the reaction time. You add a potentiometer to the + input to preset a reference, you scale the voltage divider so the opamp can accept high voltage from the amplifier so it won't blow up, and to be clever, add a zener diode to make your circuit immune to 9v battery voltage fluctuations. A few more things to add. [/QUOTE]

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