Hey guys,
I just finished putting together a .2-2A current source for use with most lasers. The source will run off of any 18V laptop charger. I have tested it many times in PSpice and also used an oscilloscope to verify that there are no large current.
Here is a schematic along with a PSPICE step response. You can see the op-amp reaching equilibrium (the simulation assumes that the potentiometer is maxed, setting the current to 2A) in the step response, and there is no current overshoot. Also, even if the potentiometer is scratchy, rather than send too much current, it will send very low current.
This could be improved with LASASORB, and is not very efficient (because the laptop output is 18V and most of that voltage has to be dissipated in resistors), but I was trying to make a simple, safe driver to run off of most laptop chargers.
The source could also drive multiple diodes in series (because of the huge 18V overhead).
***YOU MUST USE POWER RESISTOR FOR R7 and R1!!! R7 is not necessary but if you use it, USE A POWER RESISTOR***
Any critiques or suggestions are appreciated,
John
I just finished putting together a .2-2A current source for use with most lasers. The source will run off of any 18V laptop charger. I have tested it many times in PSpice and also used an oscilloscope to verify that there are no large current.
Here is a schematic along with a PSPICE step response. You can see the op-amp reaching equilibrium (the simulation assumes that the potentiometer is maxed, setting the current to 2A) in the step response, and there is no current overshoot. Also, even if the potentiometer is scratchy, rather than send too much current, it will send very low current.
This could be improved with LASASORB, and is not very efficient (because the laptop output is 18V and most of that voltage has to be dissipated in resistors), but I was trying to make a simple, safe driver to run off of most laptop chargers.
The source could also drive multiple diodes in series (because of the huge 18V overhead).
***YOU MUST USE POWER RESISTOR FOR R7 and R1!!! R7 is not necessary but if you use it, USE A POWER RESISTOR***
Any critiques or suggestions are appreciated,
John
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