Switching Circuits

This type of reset pulse is ideally provided by this circuit. Because of the high input impedance of the Schmitt trigger, long reset pulse times may be achieved without the excess dissipation that results when both output devices are on simultaneously, as in an ordinary gate device (B). ..

Frequency comparator circuit

Input 1 is used as a gating period, during which a single rising edge on input 2 will cause a logic 1 output-any other number, indicating non-identical frequencies causes a logic 0 output. ICla converts input 1 to a narrow pulse which initializes IC2 which forms a two-stage shift register clocked by input 2. On the first edge of input 2 a logic 1 appears on the output of IC2b and for all subsequent inputs a logic 0 is present. At the end of the gating period this output is.....

Audio Controlled Mains Switch Circuit

This circuit will switch off the line supply to audio or video equipment if there has been no input signal for about 2 seconds. SI provides manual operation and S2 acts as a reset. This circuit allows for time to change a tape or compact disc. ..

Video/Audio Switcher Circuit

This channel selector selects video and stereo audio from any one of three different sources. ..

Alarm Sounder For Flex Switch Circuit

This is a cross-sectional diagram of a flex switch. They can be used as pushbutton or even position sensors. This schematic diagram shows an oscillator, which is used as an alarm sounder,..

Simple light-switch circuit

The circuit is a light switch who triggers when light drops on photo resistor. It is fairly simple in construction and can be used in a million applications. The photoresistor and the trimmer work as a voltage divider and also polarize the transistor TR1. TR1 triggers TR2 and TR2 drives the relay. Trimmer R7 is for adjusting the sensitivity of the circuit. ..

Cmos touch switch

This touch switch does not rely on mains hum for switching-It-can be used with battery powered circuits. Schmitt trigger IC1 forms a 100 kHz oscillator and IC2a which is biased into the linear region, amplifies the output and charges CI via the diode. IC2b acts as a level detector..

Whistle Switch Circuit

At the heart of the whistle swatch are a pair of tone detectors, each of which is built around an LM567 tone decoder, which are supported by a minimum of additional components. This whistle switch is designed to respond to only two or more occurrences of a specific tone, or sequence of tones, within a specified period to prevent false triggering. Depending on the relay used, various ac loads can be controlled. Microphone MICl picks up the sound and U2 amplifies the signal.....

Schmitt trigger zero crossing detector

This circuit has a 100 mV hysteresis which can be used in applications where very fast transition times are required at the output even though the signal is very slow. The hysteresis loop also reduces false triggering due to noise on the input..

DTL-TTL controlled buffered analog switch

This analog switch uses the 2N4860 JFET for its 25 ohm ron and low leakage. The LM102 serves as a voltage buffer. This circuit can be adapted to a dual trace oscilloscope chopper..

Gain-Controlled Amplifier

This single-chip circuit adjusts its audio gain according to the ambient noise picked up by the microphone. When ..

Electronic Safety Switch Circuit

SI and S2 must be depressed within 200 ms of each other to activate Kl. The hold Lime is adjustable via K7...

Battery-Saving Disconnect Switch

At a predetermined level of declining terminal voltage, the circuit disconnects the battery from the load ..

zero voltage switching

The SCR coupler circuit provides higher sensitivity to input signals as illustrated. ..

Sound-Activated Switch

This circuit provides either latched switching or timed switching. U1A and UlB provide audio amplification from the ..

Twilight switch circuit

As dusk begins to -fall, the sensor (a cadmium-sulfide light-dependent resistor or LDR) operates a small horn to provide an audible reminder that it's time to turn on your lights. To turn the circuit offâ€”simply turn your headlights on and the noise stops. The base of Ql is fed through a voltage divider formed by R4, LDR1â€”a light-dependent resistor with an internal resistor of about 100 ohms under bright-light conditions and about 10 megohms in total.....

AC-static SPDT switch

An SPDT solid state relay is shown. When voltage is applied Ql will turn on, activating load #1, because the full line voltage appears across Q2, supplying gate current through Rl. When SI is closed. ..

High input comparator

The circuit uses both halves of the CA3290 BiMOS dual voltage comparator. The LED will be turned "ON" whenever the input signal is above the lower limit (VL) but below the upper limit (Vy). ..

Remote Two Way Ac Switch Hookup Circuit

This switching arrangement is the type of arrangement used in both domestic and industrial environments to allow a light or other ac-operated device to be controlled..