Cylewet 30Pcs Optocoupler PC817C 2.54mm Pitch 4 Pins DIP-4 Mounting Photo Coupler for Arduino (Pack of 30) CYT1056

I used this to control a Baofeng radio push to talk (PTT) button with an Arduino. A 200 ohm resistor is connected to pin one of the optocoupler and the other end of the resistor is connected to an Arduino output pin. Pins 2 & 3 go to ground and pin 4 connects to the Baofeng microphone via the center connector of a 3.5mm microphone jack.

Received on schedule. Only needed two but bought the bag for backups. Both chips worked as expected with out any trouble. Came in plastic lid small box for storage.

They work well but the 3 star rating is because many of them were defective right out of the packaging. Fortunately for me, I only needed a couple and was able to discard the non-working ones.

Only one complain. The part numbers were not marked on the chips

quality and quantity for the money ,