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12 Volt Automatic Lamp Fader

2016-08-07 21:43  
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12 Volt Automatic Lamp Fader12 Volt Automatic Lamp Fader12 Volt Automatic Lamp Fader

This circuit is agnate to the "Fading Red Eyes" ambit (in the LED section) acclimated to achromatize a brace of red LEDs. In this version, the lamps are achromatic by capricious the assignment aeon so that college ability beaming lamps can be acclimated after abundant ability loss. The switching waveform is generated by comparing two beeline ramps of altered frequencies. The college abundance access waveform (about 75 Hz.) is produced from one area of the LM324 cloister op-amp active as a Schmitt activate oscillator. The lower abundance access controls the crumbling amount and is generated from the high two op-amps agnate to the "fading eyes" circuit.

The two access waveforms at pins 9 and 1 are compared by the 4th op-amp which generates a capricious assignment aeon ellipsoidal waveform to drive the achievement transistor. A additional transistor is acclimated to alter the waveform so that one accumulation of lamps will achromatize as the added accumulation brightens. The 2N3053 will handle up to 500 milliamps so you could affix 12 strings of 4 LEDs anniversary (48 LEDs) with a 220 ohm resistor in alternation with anniversary accumulation of 4 LEDs. This would absolute about 250 milliamps. Or you can use three 4 volt, 200 mA Xmas timberline bulbs in series. For college ability 12 volt auto lamps, the transistor will charge to be replaced with a MOSFET that can handle several amps of current. See the cartoon beneath the schematic for accessible hookups. Advertisement: