2pcs Vishay VO615A optocouplers (DIP-4)
10 in stock.
These are the optocouplers that I use in the OptoThing module - whilst they're pin-compatible with similar devices such as the Sharp PC817 and Cosmo K1010 I find that the Vishay units give a somewhat 'smoother' sound, so they're what I use for 'production' modules.
Like the Sharp and Cosmo devices, this is a photo-transistor device.
DIP-4 package - supplied as a pair.