RE: [Chevelle-List] Stereo question.

[Chevelle 69]

Title: Message

Herb,          I am not an electrical engineer. I was only a technician. But I had to know most of the theory. Still it's been years so I could be wrong on this and somebody please correct me if I am wrong.   First, since the alternator feeds back to the battery to keep it charged, they are electrically the same point no matter where you take your power from .....unless you have resistance losses from smaller diameter wire or long distance wires or other things in the circuit (such as terminals with corroded connections) that don't allow the full potential to be felt at that point (- resistance). The alternator is the one feeding the electricity to circuits needing it or your battery would go dead. You always want to make sure that your wires can handle the current being drawn though. A 6 gauge wire should do the job.   It could very well be that the relays are chattering when switching. If that's the case, might have to research a fix.   It could also be that the alternator switching on is causing a spike as you suspect that will effect some sensitive electronics. You are on the right track in thinking capacitor. A capacitor is a voltage device ....it filters voltage fluctuations, and it won't pass DC current, so it has to be from the positive line to the ground. A choke (coil) smoothes out fluctuations in current. A fairly good filter design is a choke and a capacitor working together.  One of the more common designs for electrical filtering is a capacitor with a choke then another capacitor. That's called a Pi  filter due to it looking like the Pi symbol. I haven't look at Radio Shack lately but they may have something like that already to install.   I say go for the voltage/current filter first, then troubleshoot the relays. They may not be hefty enough to handle the load. They may need some filtering that the filter would solve.                                                                          Steve   -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Herbert Lumpp Sent: Saturday, October 05, 2002 8:10 PM To: Chevelle List Subject: [Chevelle-List] Stereo question. Ok all you stereo gurus...  Hopefully somebody can help, the guys at the local stereo store are stumped.   If I have my stereo on (not loud but normal listening volume) and the electric fans kick on, I get a huge thump through the woofers.   The alternator is a CS130 putting out 105 amps.  The fans turn on/off with a thermo switch through a pair of relays.  The sub amp is running 6 gauge power wire directly off the battery and the fans' main power feed off the alternator.   It sounds to me like the fans are causing the alternator to suddenly put out some juice and the sudden power output is causing a surge through the system resulting in a huge thump through the woofers.  Am I on the right track or way off base? (no pun intended)  Will one of those big capacitors in the power line to the amp absorb the surge or do I need to try something else?   Thanks. cYa-   Herb Lumpp 1966 El Camino ACES 3509, MCC 528 http://users.adelphia.net/~hlump/