P1 on this Radio Shack circuit is a 6 V lamp with current up to 500 mA depending on Q2. The frequency is given by C1 which can have a modern standard value such as 3.3 uF or even 4.7 uF.
This 3 + 3 V symmetrical source circuit uses an old operational amplifier. The circuit is from an...
This circuit for low frequency data transmission was found in the May 1977 issue of Radio...
This circuit was obtained from an English documentation, with the purpose of carrying out the...