This circuit is from a 1966 publication. The frequency depends on the capacitors and on R1 which can have values between 47k and 2.2 M typically. The supply voltage can be between 200 and 300 V.
This circuit works with the previous one, generating counting pulses for random draws. The circuit is...
This circuit was found in Popular Electronics. Its purpose is to warn the visually impaired when a glass...
This circuit is from an American magazine that no longer exists, Modern Electronics, in a February...