Video Signal Carrier Circuit
In the video system of Figs. A and R, a single coaxial cable carries power to the remote location, selects one of eight video channels, and returns the selecte...
Visible-Light Audio Transmitter Circuit
In the visible-light transmitter, a 7805 voltage regulator is connected in a variable-voltage configuration, and an audio signal is fed to the common input, to...
Light-Wave Voice-Communication Transmitter Circuit
This transmitter uses a 741 op amp as a high-gain audio amplifier, which is driven by a microphone. The output of the 741 is coupled to Ql, which serves as the...
Fm Light-Beam Transmitter Circuit
This transmitter uses two-stage amplifier Q1/Q2 to frequency modulate an NE555 (configured as a VCO) operating at about 50 kHz. The resultant FM-modulated puls...
Fm Light Beam Receiver Circuit
This receiver will pick lip IR or light beams that are frequency modulated on a 50-kHz carrier. ...
One-Way Voice-Activated Intercom Circuit
An omnidirectional electret microphone can be used to pick up the sound and convert it into an electrical signal. The output of the microphone is fed along two...
Infrared Receiver Circuit
The circuit operates from a 5-V supply arid has a current consumption of 2 mA. The output is a current source that drives or suppresses a current of more than ...
Buffer Lc Data And Clock Lines Circuit
The I2C serial bus is a popular two-wire bus lor small-area networks. I2C Clock and Data lines have open collector (or drain) outputs for each device-on the ne...
Electronic Cw Bug Keyer Circuit
This keyer uses skin conductivity to simulate the old-fashioned mechanical CW bug keyer. When the dit paddle is touched the bias on the inverter, ICl-a is shun...
Ntsc/Rgb Video Decoder
An NTSC/RGB decoder is shown here. Using a TDA3330, 1-V input video is broken down into its R, G, components, and c...
Rgb/Ntsc Converter
Using a Motorola MC1377, this circuit produces NTSC video from an RGB source. Components are not critical, except for R7...
Transmit Time Limiter
This circuit prevents making transmissions that are too long, which "time out" repeaters and/or tie up a communicatio...
Audio/Video Switcher
This circuit is a two-channel baseband video switcher. Buffer amps Ul/Ql, U4/Q4, and associated components produce a b...
Carrier-Operated Relay
A shows a COR/CAS circuit for repeater use. CR1 is a silicon diode. 2 may be any relay with a 12-V coil (a long-life...
Pulse-Frequency Modulated Receiver
This receiver uses an IR-sensitive phototransistor (Clairex, HP, etc.) mounted in a light-tight enclosur...
Cw Keyer
This electronic keyer uses four ICs (five, if the optional sidetone oscillator is desired) and operates from dc sources of 9 to 15...
Two-Wire Intercom
The design consists of an amplifier, a double-pole changeover switch and two loudspeakers: one for the master station and...
Voice-Modulated Pulse Fm Ir Transmitter
This circuit has a 741 audio amplifier, which is fed by a microphone (use an amplified type), an FM...
Ir Detector
Useful for checking TV remote controls, IR-based alarm systems, and IR sources, this circuit causes LED1 to turn on for two sec...
3-Wire Receiver/Message Demuxer
This 3-wire receiver checks the first four data bits of 16 received bits against a preset address. If the t...