Driving a low power laser

[KB]

Hi, thanks for reading this.

For safer learning purposes I want to use a 3volt laser from a pointer with my LaserShark. With the higher power lasers, a secondary power supply is necessary, with the LS supplying control power only. In the case of my 3volt laser, is this necessary? The connections image indicates a 5v signal is possible, so I'd have to reduce it obviously. Has anyone tried this?

Thank you for your time.

KB

[Macpod]

Hi KB,

You should not use LaserShark laser output channels (A, B, C) to power a laser, even for a low powered module. These outputs are intended to provide only enough current to serve as signal lines.

What you can do is use a piece of wire or a 3-block jumper to connect all three PWR_SEL lines together on the LaserShark. By doing this the EXT_PWR header will serve as a convenient leech point for the USB power.

A USB port on a computer is supposed to provide 500mA of current at 5V. Based on the quality of the computer, this voltage can vary (usually between 4.75v and 5.25v). The LaserShark itself requires ~150mA current so this means you have about 350mA to play with at ~5V.

Where you go from here will be determined by your particular laser unit. (i.e. a diode vs. a unit with an analog/ttl input line, vs a unit that just has power leads.)