VTL5C3 optocoupler

Optocoupler (also called a vactrol) used in many tremolo, envelope filter and compressor circuits such as the Tremulus Lune, Mu-tron III, and Flatline Compressor for more consistent performance than discrete LED & LDR pairs. Response time, on resistance and off resistance are fairly average, making it the most versatile among the VTL5C series. This is the Xvive reissue of the part formerly manufactured by Perkins-Elmer, Excelitas and Vactec under the same name.

Note: These are marked with a yellow dot. The VTL5C4 has a white dot and the VTL5C6 has no dot. This is the only way the three types can be visually distinguished.