Univibe LDR option

[spacecommandant]

Hi, I'm wondering if either the 5528 (2M dark resistance) or PDV-P9008 (20M dark resistance) could work in a classic Univibe circuit, which I've read used a 6M7 dark resistance LDRs.

Thanks in advance..

[bean]

I'm no Univibe expert, but I've built plenty of them and IMO a 10M dark resistance is probably the minimum you'd want. I've even used some photocells that were 50M dark but those don't seem to be easily available.

The PDV-P9008 lists a rise time of 60ms which is actually quite slow. If you can find one with a min dark resistance of 10M and a rise time of 10-20ms you should be golden. 6.7M might be totally fine. It just seems rather precise for something that is probably not manufactured with that much precision!