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Need some help/advice

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tornsoul82

New Member
Ok for a college project that would benefit me and get me an easy 'A' I decided to build myself a CarPC. I completely eliminated my factory stereo and replaced it with a 7" touchscreen monitor and the CarPC. The problem I ran into was how to get the RCA wires to speaker wire, I solved this by running the RCA to a low watt amp and then from the amp to my door speakers. The problem is when I turn on the car and the speaker port on the computer gets power it surges power through it creating a loud "click" in the speakers. It not a huge deal, but its very annoying. I got a temporary fix for this by adding a toggle switch that I have to flip on and off every time I start up the car/turn it off to turn on the amp. I am in need of a switch of some sort that will delay the power to the amp.
ex.
I start the car PC gets power -- PC sends power to AMP. I need to put on a 4-10 sec delay from the time the computer gets power till it turns the amp on.
If anyone knows a name of such switch I would be grateful if you tell me.
Thanks
 

Sceadwian

Banned
You could replace the switch with a relay (or mosfet) and use a 555 timer to generate a delay and drive the device to switch it on. The 555 timer is more than just slightly well documented on the Internet, as well as in the forums here.
 

Boncuk

New Member
You might take a look into the "audio-click-pop-suppressor" chip by Maxim-IC:

MAX9890.

On the other hand you might try to delay the speakers to be activated. The click/pop is caused in single supply amplifiers where the output cap is initially charged to 1/2 VDD.

Changing the cap value is not recommended since it has an effect on frequency response.

Boncuk
 

tornsoul82

New Member
thank you i will look into both. I wanting to get a diff motherboard for the carpc, the one i looking at has rca cables and i don't think it will surge power into it when it the comp turns on. sofar the project is pretty much complete except for that lil clicking :(

thanks again for the help

torn
 

tblo163

New Member
I had a similar problem with a stereo amp I built for mp3 play back,it worked perfectly,until I ran the engine,I solved it by fitting a filter,which I took from an old car radio HU.Just connected it in series with the power supply.Ground loops can also cause a problem,they are allways worth checking out.
 
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