I used 4 x 1.5V button cells, check the multimedia section for a photo.philguy said:On a side note, may I ask what power source you use for your BR-diode? Portable solution?
Fair comment. The problem is if you try to adjust the output optical power, a small change in voltage can cause a large change in power. In contrast, the power is proportional to the current (above threshold) so it is much easier to adjust the output power in small amounts without over driving and killing the diode. The output power is always specified in terms of current in the datasheets because it is much more predictable and consistant between devices.pseudonomen137 said:Perhaps a lame excuse, but given a set temperature a voltage and current regulator will do the same thing. As long as you aren't planning on using your laser in some extreme temperature change, I don't see why you couldn't use a voltage regulator.
Given that the 7805 is not adjustable I guess it is a moot point (another reason to use a 317).
In practice I just used a current limiting resistor due to size constraints of my case - I wanted my pointer small! Either an adjustable voltage or current regulator would be a better solution than just a resistor, but it requires extra batteries to raise the voltage into the regulator, and more room in the case to mount the circuit.