Hello LPF. New here please help /w Driver

[whatsupadrian]

Right now i found an old acdc converter, output is 6vDC at 600mA on the label. i put my DMM across them and im showing 10.3 volts. Im gonna test another converter, i hope my DMM is ok.

 

[whatsupadrian]

i plugged one in that says 12v at 1A and my DMM is reading 17.3. Am i missing something basic here or is my DMM junked?
another 12vdc at 1500ma is reading 15.1v

 

[lasersbee]

If you don't have a load on your 12V 1A (non regulated) adapter...
the voltage can easily be higher than 12 volts..

You need to put a load on the output to check the voltage... you can
use a car bulb (tail, flasher, interior...etc) Not the head light...


Jerry

 

[Warske]

If you don't have a load on your 12V 1A (non regulated) adapter...
the voltage can easily be higher than 12 volts..

You need to put a load on the output to check the voltage... you can
use a car bulb (tail, flasher, interior...etc) Not the head light...


Jerry

Jerry is right! By the time you are disassembling your car, check the 12v car battery, it should read about 13.5 v. Or check a flashlight battery, or a cell phone battery... Anyway, your meter is fine...

 

[whatsupadrian]

Not too sure what im doing wrong. But i put some power on my driver and put 7.3ohm on my bread board. using a 22ohm 22ohm and 15ohm in parallel and a 1ohm in series. I am reading 0 volts for some reason..... is my circuit screwed somehow or am i measuring it wrong?

 

[Warske]

Not too sure what im doing wrong. But i put some power on my driver and put 7.3ohm on my bread board. using a 22ohm 22ohm and 15ohm in parallel and a 1ohm in series. I am reading 0 volts for some reason..... is my circuit screwed somehow or am i measuring it wrong?

Sounds like you are measuring it OK, though if you do get it to work, that 15 ohm resistor in the load is going to get hot if it is only a quarter watt.

The thing is to check the other voltages, starting with the input voltage. If you need more help, you can re-post that schematic with the voltages annotated.

 

[whatsupadrian]

there is obviously current voltage passing through the circuit. i powered an LED and it is is dimly lit, although i don't think its a bright led.

 

[Warske]

there is obviously current voltage passing through the circuit. i powered an LED and it is is dimly lit, although i don't think its a bright led.

So, your LED is sitting in for the laser diode? Sounds like you have maybe 1 mA through it. When you substitute your 7.3 ohm load, it would have .001 * 7.3 = 0.0073 - 7.3 mV across it. That could well look like 0 v, depending on your meter.

So if you put in a 1k resistor for the load, do you get about 1 volt on it? What is your power supply voltage?