When SI (sensor) is closed, power is applied to U2, a dual timer. After a time determined by C2, CI is ene..
Insulated-gate, field-effect transistor (IGFET), Q2 and silicon photo cell Zl form the heart of this circuit. Transformer T1 is an audio-output type, but it"s reversed in the circuit. A sudden flash from a photoflash unit detected by Zl sends a voltage pulse through the low-impedance winding of Tl via Rl. That voltage pulse is stepped-up in Tl"s 500-!l, primary winding before being rectified by Ql. Transistor Ql is used as a diode; its emitter lead was snipped off.....
Pulses from the distributor points are passed through a current limiting resistor, rectified, and clipped at 4 volts. Via Q1 and the diode pump, a dc voltage proportional to engine rpm is presented to RV1; the sharp transfer characteristic of a CMOS gate, assisted by feedback, is used to enable the oscillator formed by the remaining half of the 4011..
The meltdown is a magnet held to a small stand by ice. A reed switch is below the magnet..
The ramp voltage from the low frequency oscillator 1C1 modulates IC2 thereby producing a rising and falling tone like the siren ..
When the light beam that falls in the CDS photocell is interrupted, transistor (EN3904) conducts thereby triggering SCR1 (CI06) and activating alarm bell. SI resets the SCR. The alarm bell should be a self-interrupting electromechanical type...
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,..
The base of Ql is connected to the car`s ignition circuit; the easiest point to make that connection is at the ignition switch fuse in the car`s fuse panel. Also, one side of the piezoelectric buzzer is connected to the instrument-panel light fuse; when the headlights or parking lights are on, the instrument panel is lit, too. When the headlights are off, no current reaches the buzzer. Therefore, nothing happens. What happens when the headlights arc on depends on the.....
Many devices operate from a car"s 12-V electrical system. Some require 12 V; others require some lesser voltage. An automobile battery"s output can vary from 12 to 13.8 V under normal circumstances. The load requirements of the device might vary. This circuit maintains a constant voltage regardless of how those factors change. Simple circuit, A, uses a 7805 voltage regulator. ..
Two SCRs are used with two sensor loops. One loop uses series switches, the other loop parallel switches. When a switch actuation occurs, the SCR triggers...
IC1 generates a pulse that modulates the 1000-Hz tone generated by IC2...
False alarms produced by semiconductor failure are impossible with this burglar-alarm circuit equipped with relays. What"s more, the circuit is virtually immune to false triggering. With a standby current of less than 0.1 mA, the circuit offers all the features an alarm needs: entry and exit delays, a timed alarm period, and automatic reset after an intrusion. One CMOS CD4093B quad NAND gate, IC1, supplies both logic and analog timing functions with the aid of.....
The tone generated by a 555 oscillator can be turned on (activated) by heat or light. That causes Ql to conduct transistor W2 (TIP 3055)...
When liquid level reaches both probes, alarm is turned on..
Most circuits that provide an electrical stimulus for research subjects are constant-voltage designs; this circuit is a constant-current design. Stimulator circuits must be isolated for two reasons: to ensure safety and to minimize interference. Isolated stimulators are essentially two-terminal devices; output currents can flow only between tbe two output terminals and can at no tiroe flow through any other path, such as the power ground. ..
This de adapter provides a regulated 9-V source for operating a Kenwood TR-2500 hand-held transceiver in the car. The LM317T"s mounting tab is electrically connected to its output pin, so take this into account as you construct your version of the adapter. ..
No electrical contact exists between the circuit and the conductor. The 7474 flip-flop is triggered by the output ..
Four parallel switches are used to monitor four positions. When a closure occurs on any switch, SCR1 triggers, which sounds the alarm...
This light-dependent sensor uses LDRs to detect the presence or absence of light. As long as the light source striking the LDRs remains constant, the alarm does not sound. ..
Using a few bipolar transistors, this circuit acts as a flood alarm. When liquid touches the probes, leakage current biases Ql,..
Operational Amplifiers
Computer Systems
Oscilloscopes
Transmitters & Receivers
Sensors & Detectors
ANSI Standards
Low Frequency Amplifiers
Power Amplifiers
Number Systems
Regulated Power Supplies
Analogue Filters
Digital Gates
