With the capacitor used, this circuit provides delays of 40 to 60 seconds. Larger capacitors can be used, and the SCR supports an equivalent. The circuit is from the 1977 RC semiconductor manual.
This circuit was found in an English magazine from 1973. The magazine no longer exists, but the...
This radio version of 1 transistor, extensively explored on this site and in this section, is from...
This dual control was based on Texas Instruments documentation for the CD4050. The circuit has two...