General Electric suggests this circuit in an 80's documentation. The circuit makes use of PUTs that are not common components today. Note the timing components that may change.
This circuit came out in a 1978 American publication, but can be assembled with transistors BC547 or...
The components of this filter are calculated using the formula f = 1 / RC and it can be...
This common circuit with two transistors was found in an old French publication. The supply can be...