How to use linear optocoupler

Status
Not open for further replies.

Fluffyboii

Active Member

Circuit requires some DC offset so I implemented a summing amplifier. The thing I am not understanding is to how to choose resistor values.
Looking at the graph for 6V I need 460 ohm led resistor. Can I impose my input signal over 5.5V DC like this and calculate for 5.5V + 0.5V signal. The servo photo diodes are even more confusing since its gain is very low acording to datasheet. Shouldn't currents passing through both of them be the same. At 10mA "If" current 100uF is passing through photo diode so how can I pick the R1 and R2 values according to this information. Should I just use 60K so that 100uA is passing through the resistor or is there a other way of calculating this. The op amp setup with no feedback is confusing too.
 
I thought about it but I wasn't able to find the model for that linear opto, now that you send it I will check it for sure. I use to use LTSpice so I should be able to replicate your circuit.
 
It does work. When I was testing it without load I noticed that output voltage started increasing and got 3X of original output voltage around 180Khz. I guess I hit some resonance point of something and I should have tested with a small load like a 10K resistor. Putting a RC filter to limit the output frequency solved the issue and tested it with cardiac wave like output of wave gen. I used 33K resistor for servo diodes. Didn't check if 22K or 10K works but I guess it doesn't matter.
 

Attachments

  • IMG_20221129_182757.jpg
    636.6 KB · Views: 278
  • IMG_20221129_181321.jpg
    557.1 KB · Views: 278
  • IMG_20221129_181128.jpg
    515.5 KB · Views: 264
  • IMG_20221129_181412.jpg
    541.2 KB · Views: 262
Status
Not open for further replies.
Cookies are required to use this site. You must accept them to continue using the site. Learn more…