This 2-tube amplifier was found in a Japanese publication of 1964. The circuit has excellent sound quality. The power supply is not given and must provide a voltage of 300 V.
This circuit monitors the humidity of a pot or plant bed, providing indication on two LEDs. The...
This circuit is from the 2005 Linear Technology Application Manual. It provides an indication of the...
This circuit activates an old conventional cassette recorder when the telephone line is answered and...