This two-transistor circuit is from a December 1964 Radio Electronics. Modern transistors can be tested. The headphone must be high impedance or crystal with a 2k2 resistor in parallel.
Found in American documentation from the 1970s, this circuit is intended for amplifying analog TV...
This circuit uses only passive components and the instrument can be a microammeter or the lowest...
This oscillator generates quadrature signals, that is, with a 90-degree lag. The frequency is...