This 555-based circuit was found in the August 1976 issue of Radio Electronics magazine. The tone frequencies are provided by the capacitors connected to the 555 IC.
The circuit shown is from the GE semiconductor manual of 1977. In the table we have the values of the...
This 1967 Ferranti circuit uses company components. These transistors can be replaced by modern...
This 15 V regulator uses the integrated 100 mA L series. The circuit was suggested by Motorola's Linear...