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Electrical Engineering Assist, Please
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Join Date: Apr 2001
Location: San Antonio TX USA
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Apr 7, 2014, 10:31 PM
I have a 12vdc, 20A max power supply that's intended to drive LED arrays (light strips, etc.), and in addition to running some LED strips, I want to run a couple other devices - an aftermarket car backup video monitor and two micro cameras. Everything is rated at 12vdc, but I have this nagging thought that I should use some sort of isolation resistor between the light power and the power lines to each of the other devices.

The cameras are rated at 500mA each and the monitor something like 700mA.

Is it really necessary to isolate 1/4" or 1/3" CMOS cameras and a 3" diagonal video monitor (all analog)? If so, what resistance and power rating would I need?


Glenn -----OTR/L, MOT, Tx
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Join Date: Jun 2001
Location: Chicago, Bang! Bang!
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Apr 7, 2014, 11:42 PM
I want a "Glenn's Neon Ground FX Build" thread.
Join Date: Jun 2000
Location: California
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Apr 8, 2014, 12:31 AM
There's no need to isolate the loads from each other. However, check the video monitor and cameras with all loads running. If the power supply has a voltage ripple, it may show on the monitor. If it doesn't, stop worrying about it.

If the ripple does cause noise or distortion, then you might want to condition the power to the monitor / cameras a bit more. An inline inductor would be the way to go, not a resistor.
Join Date: Apr 2001
Location: San Antonio TX USA
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Apr 8, 2014, 09:23 PM
reader50, thanks. I had figured that if the power supply was built to drive LEDs it would be pretty clean, but I was concerned that loading it, even a little, might cause issues with the different loads interacting. I've run the monitor and one camera, but not the LEDs with them; I don't think ripple will be an issue, but now I know what to do to address it if it rears its ugly head.

subego, I don't fit in a Neon. Tried it, got a back ache. Now if it were building Luke's speeder, I might just be there. But not a Neon. Oh heaven help us all, no.

Glenn -----OTR/L, MOT, Tx
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