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How to connect the lightbulb for the photoresistor


zaboomafoo

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Hello,

I am building a floor controller for behringer VAMP2. It is mostly done. I wanted to connect to it an expression pedal from an old hammond organ. It has a photoresistor and from what I can see a regular lightbulb inside. I am not sure how to connect the bulb. I tried to conect a 9v battery to the bulb and it seems to work fine.

I tried to connect the bulb to the +/- 5V from the core board, which brings the voltage down to below 3V and nothing works. Should I try to connect it directly to the power (J1 on the CORE board). Or maybe to one of the DOUTs?

It would probably make it easier if this was a LED, but I don't think I can take this thing apart and replace the bulb with the LED. I will try that if nothing else works.

Regards,

Frank

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Or maybe to one of the DOUTs?

... you better don't do this. If you want to control it over a DOUT, you should take reed relais to connected, which is triggered by the DOUT.

But since it does not have to be controlled, you can power it directly. Don't you have any ratings written on this photoresistor package? Or at least a "type" label to find a datasheet?

Greets, Roger

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You are correct Roger, the bulb doesn't need to be controlled. it should be always on.

I will try to connect it directly to the power in, before the power supply and se how it goes. I might fry the wallwart if too much current is drawn.

Unfortunatelly I don't have any specs on this pedal. It came of an old '70 hammond organ that I got off ebay for $0.01. This was probably the best purchase I ever made on ebay. this thing became a donor for many things - nice 30w solid state amp, 12inch alnico speaker, spring reverb (that is now a nice guitar combo), 61keys for the midi controller keyboard. And now I have this pedal that just begs to be used for something :) .

Regards,

Frank

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I solved this problem. It turned out that it was easy to just take the bulb out of the pedal. I took the bulb, broke the glass and soldered a LED inside the bulb's base. LED is controlled from one of the DOUTs. Everything works fine. Now I have to add some code in my program that will handle the pedal movements and send some CCs.

Thanks

Frank

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