This circuit was obtained in a Electronics World of 1968. The transistors can be equivalent as the BC558 for the PNP and the BD135 for the NPN powering lamps from 3 to 12 V according to the supply.
Using an operational amplifier with FET, this voltmeter has a high input resistance. The circuit has...
This circuit was found in a Linear Technology documentation from the 90's. The integrated circuits are...
This circuit generates signals controlled by crystal and can generate marks up to 30 MHz of 1 in 1...