Need Help... Yet Again.
#11
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I think the key here is the aftermarket stereo. Back in the old days when I messed with aftermarket stereo systems, it was quite common to have a "ground loop" problem where you'd hear a whining noise through the speakers and would get louder with engine rpms.
The solution, I seem to remember was to either find a common ground for all the audio equipment and/or get a ground loop filter (or isolator) from a place like Radio Shack.
It sounds like that's what's going on here...
The solution, I seem to remember was to either find a common ground for all the audio equipment and/or get a ground loop filter (or isolator) from a place like Radio Shack.
It sounds like that's what's going on here...
#12
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Originally Posted by Rudy' post='333816' date='Sep 12 2006, 03:57 PM
I think the key here is the aftermarket stereo. Back in the old days when I messed with aftermarket stereo systems, it was quite common to have a "ground loop" problem where you'd hear a whining noise through the speakers and would get louder with engine rpms.
The solution, I seem to remember was to either find a common ground for all the audio equipment and/or get a ground loop filter (or isolator) from a place like Radio Shack.
It sounds like that's what's going on here...
The solution, I seem to remember was to either find a common ground for all the audio equipment and/or get a ground loop filter (or isolator) from a place like Radio Shack.
It sounds like that's what's going on here...
#13
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Originally Posted by Heiss5' post='333817' date='Sep 12 2006, 06:02 PM
I'm not getting any added noise when I rev the engine though, and I'm fairly confident that all of the audio equipment in my car is sharing the same ground, I'll find out though.
Hope I'm not preach to the chorus.
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Originally Posted by dlevi67' post='333793' date='Sep 12 2006, 03:13 PM
Adding a capacitor in parallel to the socket should help - possibly two caps in parallel (one electrolytic say 10,000 uF // 0.1 uF mylar or other high Q material to filter high frequency noise above 10kHz - electrolytics tend to "fail" that test, or at least they did 20 years ago when I last studied these things
). This would mean that actually the noise is always there; it simply does not get amplified enough until you pump up the volume.
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Originally Posted by dlevi67' post='333793' date='Sep 12 2006, 11:13 PM
Adding a capacitor in parallel to the socket should help - possibly two caps in parallel (one electrolytic say 10,000 uF // 0.1 uF mylar or other high Q material to filter high frequency noise above 10kHz
It's more likely to be a harmonic of 50Hz audible at low audio power.So I think, like the previous post, you're filtering entrely the wrong frequency band with this circuit.
ABC
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Do you really think that this sound caused by the inverter is LIKELY to be above 10KHz??!!!
It's more likely to be a harmonic of 50Hz audible at low audio power.So I think, like the previous post, you're filtering entrely the wrong frequency band with this circuit.
ABC
It's more likely to be a harmonic of 50Hz audible at low audio power.So I think, like the previous post, you're filtering entrely the wrong frequency band with this circuit.
ABC
1. By having a 10,000 uF as the main capacitor, you are effectively filtering out any frequency above about 100 Hz, assuming an inverter load resistance of 0.5 Ohm (0.5 Ohm is a reasonable value, given it's exactly 300 W for a nominal 12 V) cutoff frequency is almost exactly 50 Hz.
2. All spikes ("static") have a very high proportion of high frequency signal, and it is good practice to put a small, high quality cap in parallel to high capacity electrolytics to filter out these spikes. This lowers the low pass frequency further, though in practice it does not really affect it, as the total capacity is practically the same (0.1% difference).
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