ps2501-1 opto

[simple&cheap]

what ohm resistor should I use if I'am operating a ps2501-1 opto with 6v. :?:

 

[lavenatti]

It has an absolute maximum current rating on the diode of 80mA. This would mean a 70 ohm resistor (which is really on the low side).

You probably won't need much more than 10 mA (depending on your application) so anywhere from 470 to 680 ohms should suffice. The less current you run through the diode side of the device the longer it will last. You could even try a 1K resistor, it will probably work.

 

[simple&cheap]

thanks Lavenatti, one more? does the resistor on the diode side have any effect on the transistor side. just trying to learn alittle about optos as I go for a little home project.

 

[lavenatti]

Yes, it can limit the current that flows through the transistor, very similiar to current applied directly to the base of a bipolar transistor.

Try hooking up an LED and resistor with power to the transistor side and vary the current throught the diode side with a pot. You should be able to make the LED change in brightness. (put a 220 ohm resistor in series with the pot and use around 6 volts, you don't want to blow up the diode side of the opto.

 

[simple&cheap]

thank you again you have just cleared up alot of ?s I thought that was right. but was just not shure. I'm using a PIR motion detecter to start
a timer curcuit that has 2 555s that drive the opto. on the proto board
Iwas using a led on the transistor side. but because of some thing I saw
on a drawing I had a 3k resistor on the diode side and the testing led was very dim. On the finished board the opto will drive a camera shutter.
SO min is 70 ohm but I can increase that as long as it will still operate the shutter. Thank you have been very helpful to this simple minded old man

 

[lavenatti]

Glad I could help. Remember 70 ohm is the minimum at 6 volts.

 

[simple&cheap]

I,m back to this again I've got a chance to use a 12f629 pic chip ( instead of the 555) to drive the opto the outputs of the 629 is 25ma. max. just to be safe what is the min. ohm resistor I can use between the 629 output and the opto diode. thanks again this is a great place for help.

 

[Nigel Goodwin]

I,m back to this again I've got a chance to use a 12f629 pic chip ( instead of the 555) to drive the opto the outputs of the 629 is 25ma. max. just to be safe what is the min. ohm resistor I can use between the 629 output and the opto diode. thanks again this is a great place for help.

I would suggest about 150 ohms minimum, but would probably recommend 330 ohms or so. It's only ohms law!.