Found on an 80's Elektor, this circuit uses common components, being the diode a general purpose germanium. The coils select the frequency range of the indicator that reaches 60 MHz.
This circuit was found in a 1964 Electronic Design to indicate when a headlight or flashlight bulb is...
In the figure we have a way of obtaining a 13,2 V with current up to 5 A using an integrated 7812...
Using a 4046 PLL this circuit generates rectangular signals in three wavebands that depend on the...