Optocouplers lots of them. ideas for use?

[wormfooduk]

Hi, ive just been given a bag full of tubes or these

http://www.farnell.com/datasheets/630968.pdf

Never used one before am i right in saying its like a led and ldr in one package?

What can i use them for i dont think ive ever seen a design with them in?

[deadastronaut]

here ya go..cool..

http://www.jaycar.com.au/images_uploaded/optocoup.pdf

[wormfooduk]

Thanks for the guide should help alot. But has anyone used one in a Tremelo or comp?

[cab42]

Search for Flatline compressor. I really like mine.

Regards

Carsten

[merlinb]

Thanks for the guide should help alot. But has anyone used one in a Tremelo or comp?

Those optocouplers are designed to be basically on or off, so they're not ideally suited for analog work. With a few opamps you could build a bypass/looper box, with the phototransistors acting as switching elements.

Another possibility is to switch them on/off at high frequency (above audio), at which point you can treat the transistor as 'a bit like a variable resistor'. Google "pulse width modulated phaser" or something; a few have been built.

[Hides-His-Eyes]

Search for Flatline compressor. I really like mine.

Regards

Carsten

these are digital optocouplers, not analogue ones.

[pjwhite]

These are not strictly digital optocouplers.  If you read the data sheet (and refer to Fig. 4 - Output Characteristics), you will see that you can put a small current in and get a small current out, put a larger current in and get a larger current out.  The CTR (current transfer ratio) is about 20%, so, for example if you were to put in 20 mA, you would get 100uA out.  The transfer is not completely linear, but it certainly may be useful in some effects pedal designs.

[amptramp]

Not to be picky, but if the current transfer ratio is 20% and you put 20 mA in, wouldn't you get 4 mA out?

20% = 0.2

0.2 x 20 = 4

[pjwhite]

Yeah, you're right.  I didn't check my math.  I was going from the graph, but didn't really spend time analyzing it. 

[Hides-His-Eyes]

So using a 150R series resistor, a wide-sweep LFO at close to the 9V rails would give you ~1-10mA current transfer; where does our input signal come into that? If we put our signal, biased, on the base, 9V on the collector and the photons limit the current output to give us our tremolo?

Can we ignore the base and use the C-E junction as a current limiter = resistor-like thing? PT2399 modulator?

[Mark Hammer]

The base-collector, and base-emitter, path of any bipolar transistor is essentially a diode.  Has anyone ever tried using an LED/photo-transistor package like this as a back-to-back diode pair for asymmetrical clipping?

In this case, you'd essentially tie pins 1 & 5, and 2 & 6 together for a clipping pair.