I have a opto coupler (4n25x) that I want to use to isolate my PC from a stepper motor driver and controller and I can't seem to make the LED side have any effect on the transistor side.
I'm using a power supply I put together from a old pc, and I'm wondering if the volts or amps have anything to do with my problem.

I'm kinda new at this stuff, obviously. I'm not exactly sure the best way to utilize the transistor side. I know there a number of ways to do it.
Some direction would be great.
parallel is about 3.7 to 5v, for the led, and I want to make the driven transistor 12v.

Rocky

 

Are you able to post schematics of the circuits you have built?

 

why 15k resistor? how do you know?

Thanks for your help.

 

how do you post schematics? is there a utility in this website?

 

how do you post schematics? is there a utility in this website?

There are provisions for attaching images, preferably in .PNG format.
Click the "Go Advanced" button below the reply text box.
Then click the "Manage Attachment" button under "Additional Options" under the reply box.
Navigate to where the image is stored on your hard drive, and select it, then click the Upload button.

 

Thanks sarge, your alot of help. nice suit.