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| Is there a simple circuit solution for this? |
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| ballen:
Device is packaged in a small metal cylinder with an adjustable focusing lens and a red and black lead coming out the back. I don't think I can see what's inside without destructive disassembly :( |
| magic:
Well, nevermind then. Mine was like shown below and yours is probably similar if it maintains constant current. Actually, with one difference. I think R2 was some sort of a thermistor originally, but I damaged it while replacing power leads and installed a fixed resistor instead. |
| RJSV:
Let me see if I got this right, please: You present a question: "...need proper fixed VOLTAGE..." "...for a FIXED load...". NO, it's not a fixed load: it's a semiconductor. After which a likely very experienced reply comes: "...don't connect directly to a voltage..." So, you then proceed to another possibility: A VOLTAGE, this time created by a zener, followed by an inevitable reply, explicitly warning: "laser diode is a current-controlled device.." Generous with advice, that reply also mentions things (like necessary VOLTAGE) 'can vary a lot, with temperature..." THEN you introduce another LDO regulator option and focus on... wait for it: VOLTAGE output to laser diode. Granted, of course you have to ensure the headroom is sufficient, there. To which, the predictable reply ends with: '...to make a constant current sourc, e...'. You then further 'experiment' with drive VOLTAGE, even mentioning current NOT constant, a little. (Whatever that means), 'happily' working, (and again, at whatever the device temperature was then...who cares?) And yet, yet, again REPLY comes: to focus on 'current setting', for a temperature-dependant semi-conductor load. Ok, I'm done. Set your sights on 'device current'!!! I made that mis-step a bunch of times, (tried voltage controls). |
| NiHaoMike:
A MOSFET current sink can have close to zero voltage drop. |
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