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Lamp Push-To-Test


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Aug 18, 2006
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I have lamps on my panel.. one is for the starter, one for low/hi voltage, one for alternator warning, and the last one for warnings from my MGL cht/egt instruments.
One of things I really liked about my Yak52 was a button you could push to check all your lamps were working. This way you never had to wonder whether the one qreen gear down lamp was blown, or whether there was actually a problem with the gear- etc.
So I have installed push to test switch next to mty lamps .. but whilst wiring up hit a snag. The way it works is that all lamps are grounded, and connected to both the source (instrument, alternator, whatever) and also the test button, which is connected to power. If you push the test buttons, you close a short circuit to power, and they all light up. If not, they are all off, unless a power signal comes from the instrument.
Problem... if one instrument fires up a lamp, the power travels additionally back to the test button, and then back down to the other lamps, and they ALL light up.. not the intended outcome! I only want the correct lamp to come on, obviously.
I'm out of my depth now.. I THINK what I need is a diode to stop the power travelling backwards to the switch and then to the other lamps.. but I have no idea to be sure.. and also don't know what size/type to use? I have some spare diodes from the ones I used between the solenoids.. but I'm assuming they are big amp/volt ones... and wont be appropriate???
Anyone know how to size a diode?


Edited by: macwolf

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