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.

Telephone Amplifier with TDA7052 (CB990E)
Like the previous circuit, this is used in the analog part of the telephone lines. The same...
Color Bar Generator (CB25390E)
This analog TV circuit generates bars in the NTSC standard. We found it in the July 1991 issue of...
Voice operated transmitter (CB20412E)
This transmitter kicks in when the microphone picks up sound. This sound then modulates the signal...