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Old 11-29-2010, 03:18 PM   #1
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Default COP testing

Anybody know how to test cops? I did some interweb searching and mt searching and have not come up with anything helpful. Can somebody impart some resistance values I should see (mainly thinking the resistance across the driver will be most important/helpful and I think it should be around 5k). Thanks!
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Old 11-30-2010, 10:55 AM   #2
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1: Put the ignition coil on the bench.

2: Have a source of 12 volts available, such as a car battery. A wall-wart probably won't cut it unless it's rated for well over 1000ma (1A), and more is better here.

3: Insert a spark plug into the coil.

4: Take a length of wire, strip one end several inches, and wrap that end around the threaded portion of the spark plug, securing it with tape, zip-tie, etc. Connect the other end of the wire to the GND or (-) side of the 12v power supply.

5: Connect the (+) and (-) terminals of the coil to the 12v power supply.

6a: When I've done this, I have had a second power supply available to supply 5v to the trigger input. This one can be a small wall-wart, or one of those battery holders that puts 3 AA batteries in series.
i: If you have this available, connect the (-) or GND side of the 5v supply to that of the 12v supply.

ii: Tap the (+) wire of the 5v supply to the trigger pin of the coil very briefly, and the plug should spark.
6b: If you do not have a 5v supply available, you can probably get away with triggering via 12v:
i: Install a 1k resistor in series with a piece of wire.

ii: Connect one end to the (+) terminal of the 12v supply, and tap the other to the COP's trigger terminal.

iii: I don't guarantee that this will work / not destroy your coil.
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Old 11-30-2010, 05:26 PM   #3
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I just did resistance checks across all of my cops and they were all within 1% of each other. These are the values I got:

+12 to Gnd. 27KΩ

Gnd. to Trigger 346.5Ω

Gnd. to Tach. 0Ω

+12 to Tach. 485.8KΩ

+12 to Trigger 27.2KΩ
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