 LED Instrument Illumination |
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| lapuwali |
 Aug 26 2005, 12:53 PM
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#21
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Not another one!  Group: Benefactors Posts: 4,526 Joined: 1-March 04 From: San Mateo, CA Member No.: 1,743   |
I did. Here's an example of why, and a dimmer that works, but isn't just a pot: Dimming LEDs It may well be that NH Speedo provides a circuit board for the inside of the gauge with several LEDs, a voltage regulator, a transistor, and a handful of resistors, as shown here. They could also be using a simple timer to produce dimming via PWM. None of this is all that expensive, but it's more than just a bulb, a wire, and a pot. |
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| mightyohm |
Aug 26 2005, 01:01 PM
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#22
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Advanced Member Group: Benefactors Posts: 2,277 Joined: 16-January 03 From: Seattle, WA Member No.: 162 Region Association: Pacific Northwest |
If I were doing this I would dim them with PWM in response to the voltage change across a voltage divider formed by the dimmer knob and a dropping resistor. The downside is you would need a custom circuit to connect all the LEDs to and you wouldn't be able to use them as a drop in for regular light bulbs. (Unless you included a tiny dc-dc converter and the pwm circuit inside the base of each bulb.)
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