This analog volt-ammeter was found in an Electronics World of 1968. It makes use of a 0-1 mA analog milliammeter. Accuracy depends on the components.
This circuit is indicated to operate from high impedance sources as piezoelectric transducers....
A quartz crystal-controlled oscillator, capable of operating up to approximately 1 MHz, can be...
This circuit is based on an old operational amplifier, having been found in documentation from the...