is a vactrol the same as an opto coupler??

[loss1234]

i am confused again. i know vactrols are an ldr and an led. i also see optocouplers that arent called vactrols that have an led and an ldr in a chip. is there a difference (other than that vactrols cost more???)

thanks

[blue hell]

Optocouplers usually have an LED and a photo transistor (so not an LDR).

The difference is that an LDR is just a resistor so it has no polarity, where a photo transistor can conduct only in one direction. Also an LDR has a slow response on light intensity changes and a photo transistor has a fast response. Optocouplers are used mainly for isolating digital signals, although it is possible to operate 'm in the analog domain.

[factus10]

Vactrol is a trademarked brand name for opto-isolators made by Perkin Elmer. Silonex also makes opto-isolators under their Audiohm brand. Clairex used to make the CLM-6000 that Craig Anderton loved to use in his projects, most notably in Electronic Projects For Musicians.

Opto-isolators are optocouplers are photocouplers.

The kind that are frequently used in electronic music projects have LED input and photocell (LDR) output (like the Vactrols and Audiohms). They are a distinct minority (in sheer numbers) of the optocouplers out there.

Photocell optocouplers are great for widely varying analog output. You can use them in just about any place where you'd use a resistor or potentiometer.

As far as I know, Vactrols and Audiohm are the only easily available production optos with LDR output.

The majority of optocouplers have a diode or phototransistor output. The PC900 (the MIDI input spec opto) and the HP138/HP139 are phototransistor output.

Phototransistor optocouplers are great for switching and digital signals (hence the MIDI input).

[loss1234]

the clm-6000 are very low resistance right? so they arent as useful for a lot of things.


i guess i need to order some vactrols

thanks alot

[elektro80]

Cool.. I found this one at the Audioohm site. Nice