This 1965 circuit uses a Philips 4068 tube to measure extremely small charges. The circuit has as indicator a micro ammeter and the transistors are of the time.
This circuit generates low-frequency sinusoidal signals. The variable capacitor is dual and the...
These circuits were obtained in an Electronics Now from the 90s. The integrated circuits are from...
This circuit for voltages up to about 20 V was found in a 90s Popular Electronics. The LED can be...