Wisconsin Parts Database Instructions and Discussion Team/Group > WISCONSIN
> Machine Parts
> Add
> Used
> Power supply 3.3V dc 4.55A ideal for laser diode
Power supply 3.3V dc 4.55A ideal for laser diode
New 3.3V DC 4.55A Power Supply
This is ideal for powering many laser diodes up to 4 watts when used with an appropriate current limiting resistor in series with the laser diode. You can use ohm's law to calculate the value of the current limiting resistor as follows:
Where Vd is the diode voltage (typically 1.8-2.2V) and Id is the diode current.
For example, to get a diode current of 2 amps, the current limiting resistor should be (3.3-2.0)/2.0 = 0.65 ohms. The power dissipated as heat in the resistor can be calculated as follows:
In the previous example, the power is 1.3 * 2.0 = 2.6 watts so a 3 watt or larger power resistor must be used.
The advantage of using a 3.3V power supply instead of a more common 5V supply is that the power lost in the current limiting resistor is much lower. For example, in the case of a 5V power supply set up for the same 2 amp diode current:
P = (5.0-2.0) * 2.0 = 6 watts (which requires a 10W or larger power resistor that will get quite hot)
