This circuit was found in a Philips documentation from 19678. The transistors are from the period with emphasis on the married pair. Modern equivalents can be used.
Audio frequencies in the 300 Hz to 30 kHz range can be measured with this circuit. Transistors allow...
This dimmer or light control for incandescent light bulbs or even small heaters, is one of many...
This amplifier for a sinusoidal function generator uses a 741 integrated circuit. The circuit is...