I'm building some LED based lights for my work trike, intended as safety daytime running lights, but with the ability to be used as headlights at night.
Using a pair of LM317s in constant current configuration, with the input source switched between them.
Would a diode be needed on the output to prevent reverse current damage to the inactive current source, like this? Yes, I know a diode will add an additional voltage drop of ~1.7V to the circuit, but given the power is being supplied by an 8Ah SLA, I think I have the headroom available, since I am driving a trio of 1W Osram type white LEDs wired in series with a typical voltage drop of 3.2-3.6V
Low beam would be configured for 90mA and high beam for 250mA.
Circuit:
**broken link removed**
Thumbnail is clickable.
Using a pair of LM317s in constant current configuration, with the input source switched between them.
Would a diode be needed on the output to prevent reverse current damage to the inactive current source, like this? Yes, I know a diode will add an additional voltage drop of ~1.7V to the circuit, but given the power is being supplied by an 8Ah SLA, I think I have the headroom available, since I am driving a trio of 1W Osram type white LEDs wired in series with a typical voltage drop of 3.2-3.6V
Low beam would be configured for 90mA and high beam for 250mA.
Circuit:
**broken link removed**
Thumbnail is clickable.