What’s a good substitute for a CL705HL for a Standel optical trem?

[Rambozo96]

Hello all I had the idea of taking the trem circuit of the old Standel amps and possibly putting it in a pedal or maybe a rack. But it appears the LDR it uses (CL705HL) seems to be very hard to find and it seems Clairex never answered my email on whenever they had any or had a good substitute.


Thanks in advance, Taylor

[pinkjimiphoton]

google search took like, 5 seconds to find a datasheet and a bunch of substitutes.


http://www.datasheetcatalog.com/datasheets_pdf/C/L/7/0/CL705HL.shtml

CL703, CL703A, CL703L, CL703L_2, CL704

[smallbearelec]

Time to take out your breadboard. You can probably hack the circuit into something you like. However, as shown, I see a few issues with making it into a pedal. The LFO is a straight phase-shift oscillator, but the power supply is +/- 32V. Better to start with a +9 V version like in the EA Tremolo:

http://www.generalguitargadgets.com/pdf/ggg_eat_sc_improved.pdf

To drive an incandesant lamp

http://smallbear-electronics.mybigcommerce.com/lamp-screw-base-1-5-volt-25-ma/

I would replace Q2 in the EA schem with a bipolar device, maybe a 2N2222. Some tweaking would be needed to get the bias right.

Clairex has not made CdS devices in many years. The good news is that numerous inexpensive types are readily available, and they can almost always be made to work, some better than others.

http://smallbear-electronics.mybigcommerce.com/photocells-cds-5mm-diameter/

You'll also have to figure out what kind of modulator icrcuit you want the photocell to drive. Numerous possibilities in the archives.

This arrangement can give a very warm, mellow trem. I hope you enjoy tweaking it.