In DDL's circuit the LM317 is used as a current regulator, so the voltage doesn't really matter. You could power that circuit with 35 volts and your only problem would be heatsinking the LM317. The laser diode takes the voltage it needs so extra voltage won't hurt the diode. The only thing you need to watch is the current.Jimmymcjimthejim said:Note how the LM317T circuit is a voltage regulating circuit. You can insert as much input voltage as you want. Yes, a red diode typically takes around 3v. You can adjust the current output with the potentiometer in the circuit, without increasing the input voltage.
In DDL's circuit the LM317 is used as a current regulator, so the voltage doesn't really matter. You could power that circuit with 35 volts and your only problem would be heatsinking the LM317. The laser diode takes the voltage it needs so extra voltage won't hurt the diode. The only thing you need to watch is the current.[/quote]styropyro said:[quote author=Jimmymcjimthejim link=1228373308/0#3 date=1228448652]Note how the LM317T circuit is a voltage regulating circuit. You can insert as much input voltage as you want. Yes, a red diode typically takes around 3v. You can adjust the current output with the potentiometer in the circuit, without increasing the input voltage.
Yes, but the circuit regulates it based on the current, diode, etc.BeavRat said:I know, but if you put in 7.5 volts, wouldn't 4 volts come out?
jonrobertd said:Yes, up to 35 volts, the laser only will get the 3 volts it needs to run and the LM317T dissipates the rest as heat. Note at those levels the heat sinking.