Any way to start a PHR without a driver?

Hello, I was wondering if it was possible to power a PHR temporarily (like a few seconds) without a driver. I only want to see if the Diode actually works before I decide to invest money (driver) and then even more money in case it is dead. I dont care if I kill the diode in the process, at least it will put my mind at ease.

Thanks,

Yer it would probably work and kill it straight away. Why don't you have any faith in the diodes :-? if you kill this one seeing if it works, you'll just need to spend more on another diode that you haven't tested yet, and the cost of a new diode could easily equate to that of a regulated driver.

I dont have much time or money to continue with the DIY projects, so I would honestly rather "accidentally" kill the diode testing it, than have it and not know whether there is still hope for it, or if I should just throw it away.

I do NOT recommend this for long-term use, but if you're looking for a poor man's driver...

If you get a 12 V supply, a decent-sized capacitor, and a heavy-duty 150 ohm resistor, you can drive the diode temporarily with about 50 mA of current.  However, you could easily damage the diode if the capacitor was charged when you attached the diode, or if there is even a momentary diode disconnect.

Make sure you are measuring the voltage drop across the resistor.  If it's not around 7-8 volts and/or you're not lasing, your diode is bad or you just broke it.

Edit:
Power supply + to Diode + and Capacitor +
Short capacitor before proceeding
Diode - and Capacitor - to Resistor terminal 1
Resistor terminal 2 to Power supply -

Plus, be sure that it is a REGULATED power supply. Some linear power packs/wall warts/ac adapters can output 2-4 volts higher than their rating when under small loads.

laserman22 said:

I dont have much time or money to continue with the DIY projects, so I would honestly rather "accidentally" kill the diode testing it, than have it and not know whether there is still hope for it, or if I should just throw it away.

Click to expand...

If it's broken, just desolder it from the driver. :-?

what I mean is that if I do buy a driver, and the diode really is broken, then I will have to buy another diode (for the driver).

I really want this to be my last diode ever. If it does work, ill go ahead and get a driver, and heatsink for it (already have a host).

Use your DMM in the Diode Check Mode. The diode may even laze dimly while you're checking it

Here's a schematic for how to build a ghetto "driver" which should at least allow you to run your laser for a few seconds without killing it...
http://www.laserpointerforums.com/forums/YaBB.pl?num=1210197694/5#5 (substitute 3x AA batteries for a bluray, that circuit is for a red)... It's safest if your batteries are somewhat dead, with fresh ones you could be in trouble. Use ohms law to tell you what value of resistor to use.. err on the side of caution. (this is basically what phoenix was suggesting above.. it's certainly not a long term solution, but it should at least protect your diode for a few seconds of testing... I'd suggest against using power from the wall, since alkaline batteries don't have voltage spikes and have internal resistance to limit the current.)

Otherwise, for a couple bucks and a trip to radioshack you can make yourself what basically amounts to the exact same thing as a rkcstr driver, here: http://www.laserpointerforums.com/forums/YaBB.pl?num=1185701612 ... This is a fully current regulated driver which protects against reverse polarity, voltage spikes, current drift, and most other things which might kill your diode.

laserman22 said:

what I mean is that if I do buy a driver, and the diode really is broken, then I will have to buy another diode (for the driver).

[highlight]I really want this to be my last diode ever.[/highlight]

Click to expand...

laserman22 said:

Hello, I was wondering if it was possible to power a PHR temporarily (like a few seconds) without a driver. I only want to see if the Diode actually works before I decide to invest money (driver) and then even more money in case it is dead. [highlight]I dont care if I kill the diode in the process[/highlight], at least it will put my mind at ease.

Thanks,

Click to expand...

Erm...

:-? :
If you want to be done with the whole bit for certain, just connect the diode directly to a battery (making certain of course that voltage is > 4V).

But what good is that kind of certainty?

btw, with all due respect to the lobster, any method that relies on a battery to not be fully charged, is a formula for disaster.

If you truly want this to be your last working laser diode, and want it to keep working, use a proper driver every time. Otherwise you may as well throw your money away... want to buy some dead laser diodes? I have a few, but they won't be cheap, I put a lot of work into getting them in that condition.


DanQ

You can easy and safely test the PHR803 diode with a 9V Battery and a Resistor. The diodes lase with >31mA and can be driven up to at least 90mA. If you aim for 60mA you are safe. You take the battery voltage (9V) minus the diode voltage (4,5V) =4,5V and divide by the current (60mA) this gives you a resistance of 75 Ohm, if you have 68 Ohm or 82 Ohm in your drawer its no problem.
The key to drive a LD with just a resistor and a battery is to have some volts for the resistor left, so you get a quite constant current. If you had a red LD with 2.7V and batteries with 3V then you cant get a defined current, it depends very much on temperature and battery condition.