Radio Shack Bargain Parts

harrybissell at harrybissell at
Mon Mar 20 22:20:02 CET 2000

If it is the single inverter "schmitt trigger" oscillator, then using a FET or a TL071 (81,82 etc) to
buffer the input pin (junction of the cap and resistor) will give a triangle wave....

I'm assuming this is the light activated theremin from the thread....

Another photo (conductive) cell could control volume...

H^) harry

 ---- On Mar 19 CHoaglin at wrote: 
> In a message dated 3/19/00 6:11:41 PM Pacific Standard Time, 
> efm3 at writes:
> << 
>  > I was in Radio Shlack today and came across (and impulsively bought)
>  > a pack of 5 cadmium sulphide photocell devices.  They were marked as
>  > "photocells".
>  I've got a bunch of parts gathered together for when I get some spare time 
> to build the therman. For the CdS cells, I managed to get some really nice 
> ones from a friend. They're really old, with date codes from the 60's, but 
> they're WAY nicer looking than the radio shack ones. They're metal cans about 
> an inch across, with a huge cell inside, covered by a quartz window. My 
> friend had a bunch of them, so I sorted through them to find a couple pairs 
> of cells with similar resistive characteristics. The cells were used in 
> street lights, to turn them off and on..(mental picture of synth-diy'ers 
> climbing streetlight poles to get parts)
> If I remember correctly, the therman uses a square wave oscillator made from 
> a hex inverter..Is there a nicer oscillator which could be substituted, and 
> is also simple to build?
> Chris

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