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.
The circuit shown in the figure is suggested by Intersil (www.intersil.com) and makes use of the...
We found this version of the automotive tachometer in a 1980s publication. Variations from other...
The battery charger shown in the figure uses two 60 W incandescent bulbs in series to limit the...