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My Changing Dump Rate on Ghurd Controller

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WooferHound:
It's Ghurds kit. I have not modified it except to put 2 LEDs instead of one, and use 1000ohm resisters instead of 470ohm.

I had never considered about induced noise possibly firing the FET. The wire is 110 feet of CAT 5 wire and the individual LEDs are on separate twisted pairs.

rossw:

--- Quote from: WooferHound on January 24, 2012, 09:55:53 pm ---I had never considered about induced noise possibly firing the FET. The wire is 110 feet of CAT 5 wire and the individual LEDs are on separate twisted pairs.

--- End quote ---

OK, I just looked at the circuit. When you said "Drive", I mistakenly thought the LED may have been on the FET "Drive" side. It appears the standard LED is from Drain to Ground, and shouldn't be the problem I thought.

Looking at it though - the 470R resistor originally in series with the LED, probably should be 470R for *EACH* LED.

While there "shouldn't" be a problem with the way you've connected it, there is a chance that higher-frequency noise is being carried back to the controller and affecting its operation. Have you tried disconnecting the long cable and see if the issue remains? (disconnect *ALL* the long wires, not just one side of each!).

If disconnecting the wires DOES make it behave "normally", I'd reconnect them and try bypassing them with perhaps 100nF to see if that tames it down. I'm sure Ghurd will make more intelligent suggestions though.

WooferHound:
Some good suggestions
Yes I can easily disconnect the long wires as they are connected through a terminal strip. However I have had very little Sun this month and have not had much actual dumping happening. Almost made it to full charge today but rain is moving in again and won't see Sun again for 3 or 4 days.

I'm just a few miles away from Redstone Arsenal and Marshall Spaceflight Center. There is a lot of military and about 1/4 of NASA. I could be getting some interesting signals from over there.

rossw:

--- Quote from: WooferHound on January 24, 2012, 10:26:19 pm ---I'm just a few miles away from Redstone Arsenal and Marshall Spaceflight Center. There is a lot of military and about 1/4 of NASA. I could be getting some interesting signals from over there.

--- End quote ---

Ooooohhhhh yeaaaaaahhhhh!

2 seconds. Is it a roughly equal mark/space ratio? (if it's cyclical every 2 seconds, is it 1 second on, 1 second off? Or more like a blip every 2 seconds?)  That could even be a mid-range radar sweeping past.

rossw:

--- Quote from: rossw on January 24, 2012, 10:04:30 pm ---OK, I just looked at the circuit. When you said "Drive", I mistakenly thought the LED may have been on the FET "Drive" side. It appears the standard LED is from Drain to Ground, and shouldn't be the problem I thought.

--- End quote ---

Some days I'm so blind I amaze myself.

I take that back. Yes, the long wires *ARE* onto the gate of the MAIN load-switching FET, and could very easily cause the symptoms. The method of testing still stands though, as does my initial suggestion to tame it.

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