This 1969 Mullar circuit appears elsewhere on this site. The circuit uses germanium diodes and the indicator is microammeter with zero in the center of the scale.
This circuit uses only passive components calculated for the desired frequency. We found it in an...
This fourth-order circuit was found on an 80's Radio Electronics. The power supply must be...
This simple circuit controls the brightness of an LED from LDRs, NTCs, PTCs or other resistive sensors....