Photocells For The Neovibe/Univibe

[smallbearelec]

The Canadian company, Silonex, that made the photocells that everyone liked for the 'Vibe was sold to Advanced Photonix, and production was moved to China. The made-in-Canada parts had an enormously higher dark resistance--over 200 meg--compared to current manufacture. I found out about this when I started getting complaints that the parts I was selling did not give the depth in the "notch" that makes the 'Vibe sound the way it does. So I have had to remainder my existing stock.

The new management has promised me a quote for a made-to-order part with the high dark resistance, and I will continue to pursue getting new stock. Meanwhile, the closest thing I can suggest is the Advanced Photonix #9203, my SKU 2506A.

[Lurco]

Hook up a max-limit parallel resistor?

[PRR]

> Hook up a max-limit parallel resistor?

The "new" run acts like it HAS a parallel resistor in it.

They have not got their process running clean and right. Stray chemistry is leaking. They can fix it, if they can be made to care. But many-many uses for photocells detect LIGHT, and the dark resistance only has to be "higher", not super-high. Audio (limiters and Univibes) are about the only things that take a photocell _way_ out to a long dark state.

I'm shocked that the Lead or Cadmium cells are even available in this the year 2014. RoHS recently ended their exemption. They can be used for "service" (DIY can hide as "service") but I'd think the service market is VERY small. Not worth running the line to make service parts. Dark-only light controllers must all be phototransistors now. "Service" of these things is to throw the whole unit away and install a new one; nobody ever opened them up to replace the photocell alone. Oil-burner flameout controls can be phototransistors or ion detectors or even thermocouples. As with Mercury-switch boiler controls, the service industry develops an "equivalent" control with the new technology. (Though I did scramble to get a true Mercury control for my old boiler when I realized that the new-tech controller was not-as-good.)

[mikro]

...by the way what dark and light resistance value should these photocells be for Easyvibe?

here i can buy a Perkin Elmer FR 48/1M that says 1 MOhm @ 0 lux and 72 kOhm @ 10 lux. also shown R=24K-72K so that's why "48" is mentioned, maybe...
would that do for Easyvibe?

thanks.

[smallbearelec]

...by the way what dark and light resistance value should these photocells be for Easyvibe?
here i can buy a Perkin Elmer FR 48/1M that says 1 MOhm @ 0 lux and 72 kOhm @ 10 lux. also shown R=24K-72K so that's why "48" is mentioned, maybe...
would that do for Easyvibe?

Those will work, but parts with higher dark resistance will give you more depth.

[Lurco]

> Hook up a max-limit parallel resistor?

The "new" run acts like it HAS a parallel resistor in it.

OOOOPS - sorry folks - I had read too hastily, and adversely mixed up the old and new ones, canadian and chinese ones. My reply was falsely assuming the current ones had "too high dark resistance".   Scrap my reply.

[midwayfair]

...by the way what dark and light resistance value should these photocells be for Easyvibe?
here i can buy a Perkin Elmer FR 48/1M that says 1 MOhm @ 0 lux and 72 kOhm @ 10 lux. also shown R=24K-72K so that's why "48" is mentioned, maybe...
would that do for Easyvibe?

Those will work, but parts with higher dark resistance will give you more depth.

The LIGHT resistance seems like the big breaker for me ... I can't understand how there can be a big difference between 20M and 200M. Both seem sufficient to completely kill any audio signal, shouldn't they? I just threw in two of a bunch of different photocells with a recent order to test.

[tomas1808]

2021 bump.

It seems that the made-to-order photocell will no longer be available. Kind of a bummer. Anyone knows of a comparable alternative? Thanks!

[Mark Hammer]

The other alternative is to simply use two photocells in series, to increase their summed maximum dark resistance.

Not particularly convenient, though.

[tomas1808]

Yeah, I was thinking about that. Not sure about the minimum resistance though. I'll have to try.