Infrared modulated transmitter (CB7247E)

This simple Philips circuit from the 1960s can use any general-purpose transistor. The signal is modulated at 2.7 kHz.

Remote Load Monitor (CB4642E)
The purpose of this project is to monitor remote loads. The windings are made in a burnt...
Electronic Bargraph Scale (CB16655E)
The scale of this scale uses LEDs, and its accuracy depends on the number of LEDs. We found this...
JFET dip meter (CB5176E)
We find this circuit in an American documentation from the 80's. The circuit has the coil given by the...