We found this circuit in a Hands-On Electronics from the 90s. The circuit must be connected to an external amplifier. Frequency control is capacitive, using an antenna for this purpose
The circuit shown in the figure can indicate the presence of static charges by lighting a 6 or 12 V...
The purpose of this circuit found in the September 1977 issue of Radio Electronics magazine is to...
Found in a 1966 publication, this circuit is a simple version of a field strength meter. The diode...