Constant current source (CB20484E)

This circuit uses a current regulator from the 90's. This component is uncommon nowadays. The transistor admits equivalent.

50 ohm Line Driver LM3900 (CB5056E)
The gain of this amplifier is 10 times and the excursion to the output voltage is 6.0 V (peak to...
Overcurrent oscillator (CB9627E)
The frequency of this circuit depends on the crystal. The transistor supports a modern equivalent. We...
Switching Power Supply (CB25379E)
This circuit uses the SQ3524, a switching integrated circuit. The circuit was found in the April...