EQD the Depths clone

[harrisxr650]

Hello,
i'm build an EQD the depths optical vibe from pcb guitar mania and i have some LDR lying around so i was wondering which of the following can be used in place of the KE-10720

8k-20k-1M
or
16k-50k-2M
or
0-20Κ-1M


Thanks

[ElectricDruid]

Tayda give the response of the KE-10720 as 10-20K to >0.5M, so either the first one or the last one look ok to me. They're both very close to that.

https://www.taydaelectronics.com/photo-conductive-cell-resistor-ldr-650nm-radial-ke-10720.html

It'll depend a bit on how *fast* they respond too. You might find you get less depth at higher speeds, but that might not be an entirely bad thing.

[MikeA]

I built a Depths and compared it head to head with an original.  I got pretty close with a bright white LED (Vf = 2.71) and four Silonex NSL5542 LDRs, which have a published spec of 20M dark and 1k to 30k light.  A close second was the Silonex NSL-7530 which specs at 6.7M to 10M in the dark and 500R to 10k in the light.  In analyzing the original Depths, there was a lot of variation between their four (unmarked) LDRs, and the distance from LED to LDR also makes a difference.  So any of your on-hand parts might sound good, I'd socket them and try different sets to see what you like.

And BTW, Electric Druid's TAPLFO03 is a killer oscillator for this circuit.