Constant current source (CB20484E)

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

Triggered Oscillator (CB21252E)
This trip switch circuit was found in a Popular Electronics from the 90's. The frequency basically...
LED Test Using the Oscilloscope (MSB008)
The LEDs act as diodes, so if good they will show the same characteristic curve. Arrangment shown...
DC to DC converter (CB8749E)
Found in a 90s 303 Circuits, this circuit has an output power of 100 mW. L1 consists of 890 turns...