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Rs232-to-cmos-line-receiver – Circuit Schematic
Rs232-to-cmos-line-receiver
This RS-232 type line receiver to drive CMOS logic uses a Schmitt-trigger feedback network to ~give about 1-V input hysteresis for added noise immunity. A possi...
Automatic-rs-232-dataselector – Circuit Schematic
Automatic-rs-232-dataselector
With this dataselector, only one RS-232 port is used to connect two RS-232 devices (i.e., printer, plotter, etc.) with a mini-or microcomputer. The operation i...
Power-line-modem – Circuit Schematic
Power-line-modem
In the 100-kHz application from left to right, the coupling network feeds into the receiver ~section on the bottom of the chip. (The external components are su...
Tone-burst oscillator and decoder – Circuit Schematic
Tone-burst oscillator and decoder
A tone burst sent at the beginning of each transmission is decoded (at receiver) by a PLL causing output from pin 3...
Intercom – Circuit Schematic
Intercom
The circuit provides a minimum component intercom. With switch SI in the talk position, the speaker of the master station acts as the microphone with the aid of...
FM (prm) optical transmitter – Circuit Schematic
FM (prm) optical transmitter
The basic circuit can be operated at 80 kHz and is limited by the PUT capacitor combination. 60 kHz is the maximum modulation frequency. The pulse repetition ra...
Optical transmitter – Circuit Schematic
Optical transmitter
Driver circuit uses an MC74LS04 and one discrete transistor...
Optical communication system – Circuit Schematic
Optical communication system
The simple modulator stage will accommodate most common LEDs. By adjusting the potentiometer, the bias of the transistor is varied until the LED is at its half ...
Fiber-optic link – Circuit Schematic
Fiber-optic link
Fiber Optic applications require analog drivers and receivers operating in the megahertz region. This complete analog transmission system is suitable for optica...
FM carrier current remote speaker system – Circuit Schematic
FM carrier current remote speaker system
High quality, noise free, wireless FM transmitter/receiver operates over standard power lines. Complete system is suitable for high-quality transmission of spee...
Automatic ttl morse-code keyer – Circuit Schematic
Automatic ttl morse-code keyer
Automatically generated dits and dahs are produced over a speed range of 11 to 39 wpm. The upper limit can be raised by decreasing R2...
Repeater beeper – Circuit Schematic
Repeater beeper
The signal from COR triggers U1 which produces a beep-gate pulse that enables the analog gate...
50 Khz center frequency optical transmitter – Circuit Schematic
50 Khz center frequency optical transmitter
The pulse repetition rate is relatively insensitive to temperature, and power supply voltage and is a linear function of V1N, the modulating voltage. Useful inf...
Optical communication system – Circuit Schematic
Optical communication system
The circuit will modulate the light from the LED using a crystal microphone or a loudspeaker output. To obtain the maximum range, the optical system must be eff...
Digital transmission isolator – Circuit Schematic
Digital transmission isolator
An optoelectronics device is used to couple a digital (TTL) signal to another system. The photodiode in the optocoupler drives an LM311 set up to produce a TTL ...
Linear ac analog coupler – Circuit Schematic
Linear ac analog coupler
With the coupler biased in the linear region by the 10 mA dc bias on the IRED and the voltage divider on the phototransistor base, photodiode current flows out ...
Video modulator 2 – Circuit Schematic
Video modulator 2
This circuit permits direct connection of composite video signals from video games and microcomputers to the antenna terminals of TV sets....
Party intercom – Circuit Schematic
Party intercom
A large number of intercom stations can be tied together. All units are connected in parallel, and the entire system is buzzed by only one signaling circuit. Ea...
Infrared receiver – Circuit Schematic
Infrared receiver
The circuit consists of Ql—a phototransistor that responds to an intensity of amplitude-modulated IR light source—and a three-stage, high-gain aud...
Infrared transmitter – Circuit Schematic
Infrared transmitter
The ultra-simple one-transistor, IR transmitter shown is designed to transmit the sound from any 8 or 16 ohm audio source, such as a TV, radio, or tape recorder...