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help buying multimeter

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nvmextc

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chido

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Your current multimeter should be fine. Are you sure you're properly testing the circuit? What do you mean you don't get any readings? Do numbers show up at all????
 
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chido

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Using 1N4004 diodes shouldn't matter. Have you tried testing it with the actual LD?
 
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nvmextc

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No, I wasn't sure how to without damaging it.
Should I test it like it says in step 4 "If your reverse diode and capacitor are already connected to your LD you can connect your test assembly to the output from your fixed resistor and the neg of the battery."
 
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chido

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Just set the pot to the maximum resistance, connect your LD to the driver, (make sure to short out the capacitor first) test the mA by using the 1 ohm resistor like you would with the 4 silicon diodes and slowly lower the resistance of the pot while checking your multimeter.
 
rog8811

rog8811

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Just be sure, you have set the multi meter to DC mv (Direct current milli volts) when connecting across the shunt resistor?  If your shunt res is 1ohm your mv reading is also your ma (milli amp) reading....

Regards rog8811

*sudden other thought....On most mm's the numbers dissapearing indicates "over-range" so if you are on mv now, change it up to the next scale, could be something like DC 20v.
My meter does up to 400mv on the lowest scale maybe yours has a lower top end?
 
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laserhacker

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hi all. i am new to the forum and read a lot of posts. just wanted to know if this meter i have would be good to check the mw on the laser i am going to build.



i have a craftman model 82344
 
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chido

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mW?? I think you mean mA. You need a laser power meter to check the output of a laser.
 
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nvmextc

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I worked out the reason why I can't find current with my DMM, it's not made for diode testing and doesn't show voltage drop.
 
SenKat_Stonetek

SenKat_Stonetek

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laserhacker said:
hi all. i am new to the forum and read a lot of posts. just wanted to know if this meter i have would be good to check the mw on the laser i am going to build.



i have a craftman model 82344
Click to expand...

you can check the current <ma>, but not the mw. That is a great model of a multimeter - depending on the circuit you build, you should be able to find a point to measure the current with no issues. If you are building the standard LM317 circuit, then you will be good to go!!!
 
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