Electrical Question #15 Need Help Please, I'm totally stumped this time |
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Electrical Question #15 Need Help Please, I'm totally stumped this time |
76-914 |
Apr 6 2014, 06:33 PM
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#1
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Repeat Offender & Resident Subaru Antagonist Group: Members Posts: 13,611 Joined: 23-January 09 From: Temecula, CA Member No.: 9,964 Region Association: Southern California |
I'm going to have several electrical questions. 1st, Is pin #8, on the 14 pin plug at the relay board, the only switched 12v+ source in the engine compartment? TIA, Kent
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Tom |
Jul 6 2015, 03:01 AM
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#2
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Advanced Member Group: Members Posts: 2,139 Joined: 21-August 05 From: Port Orchard, WA 98367 Member No.: 4,626 Region Association: None |
Kent,
If you have a meter, check the resistance of the test lamp. I'm thinking it may have a high resistance, therefore limiting current for the halogen lamp when you run them in series. Any idea what the current is for the halogen. The least load for your "on" indicator light would be an LED. Very low current, so you can use small gage wires to wire it in. As a test, put an LED across the radiator fans right up by the radiator fans, in parallel - not series. See if it works ok, then pull the wires in to the cockpit to where you want the indicator lamp. If you prefer the halogen lamp and the current is high, you can use a relay in place of the LED in the above idea, then run power for the relay from a nearby source in the cockpit. As above, test the way the relay works up by the fans first. Tom |
Spoke |
Jul 6 2015, 05:59 AM
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#3
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Jerry Group: Members Posts: 7,052 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None |
Kent, If you have a meter, check the resistance of the test lamp. I'm thinking it may have a high resistance, therefore limiting current for the halogen lamp when you run them in series. Any idea what the current is for the halogen. The least load for your "on" indicator light would be an LED. Very low current, so you can use small gage wires to wire it in. As a test, put an LED across the radiator fans right up by the radiator fans, in parallel - not series. See if it works ok, then pull the wires in to the cockpit to where you want the indicator lamp. If you prefer the halogen lamp and the current is high, you can use a relay in place of the LED in the above idea, then run power for the relay from a nearby source in the cockpit. As above, test the way the relay works up by the fans first. Tom (IMG:style_emoticons/default/agree.gif) As mentioned, the LED indicator (actually LED + series resistor) goes in parallel with the radiators fans. Use the series resistor to limit current in the LED. Allow 5ma, 10ma of LED current. Supply voltage is 14V; LED ON voltage is about 2V. So a resistor of (14V - 2V)/5ma = 2.4k ohms or (14V - 2V)/10ma = 1.2k ohms. Choose a current where the indicator is bright enough to be seen but not too bright. Power in the resistors is I*I*R = 5ma x 5ma x 2400 = 0.06W; 10ma x 10ma x 1200 = 0.12W. So choose a resistor with at least 1/4W rating. |
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