This circuit holds on the internal light for approximately one minute after the car doors are closed. When the door contacts open, a + VE pulse is applied to the base of Tl. This transistor turns on, turning off T2 and charging the 10-llF capacitor. T3 turns on, holding on the internal light. ..
When the probe is in contact with a TTL low (0) the probe emits a low note. With a TTL high (1), a high note is emitted..
The circuit is basically a NE555 monostable, the only major difference being its method of triggering. The trigger input is biased to a high value by the 22 ohm resistor. When the contact plates are touched, the skin resistance of the operator will lower the overall impedance from pin 2 to ground. This action will reduce the voltage at the trigger input to below the 16 Vcc trigger threshold and the timer will start. ..
No electrical contact exists between the circuit and the conductor. The 7474 flip-flop is triggered by the output ..
Here's an effective little combination lock that you can put together in one evening's time. To open the lock, simply dial in the correct combination on the three rotary or thumbwheel switches. With the correct combination entered, current flows through Rl into Ql's gate terminal, causing the SCR to latch in a conductive state. This sends a current through relay Kl, which responds by closing its contacts and actuating whatever load is attached. After opening the lock,.....
Pulsed sound is produced by this circuit. Ul is used as a bistable multivibrator, which acts as a contact "debou..
The relay which applies power to the wiper motor is actuated at periodic intervals by the timer circuit, closing the wiper motor contacts. Potentiometer R1 serves as the pulse rate control and potentiometer R5 as the pulse width control. ..
Use this circuit to keep the fluid level of a liquid between two fixed points. Two modes, for filling or emptying are possible by simple reversing the contact connections of Kl. The loads can be either electric motors or solenoid operated valves, operating from ac power. Liquid level detection is accomplished by two metal probes, one measuring the high level and the other the low level..
It is often desirable for a single doorbell to be operated by two buttons, for instance, one at the front door and the other at the back door. The additional button, S2 in series with the break contact of relay Rel, is connected in parallel with the original bell-push, SI. When S2 is pressed, the bell voltage is rectified by D1 and smoothed by CI. After a time, t = R{R2C2, the direct voltage across C2 has risen to a level here T1 switches on. Relay Rel is then energized.....
This circuit offers open and closed loop contacts (switches 1,2,3) that triggers the alarm ON and stays ON for 5 -10 minutes. The trigering delay (entrance/exit) is 27 seconds. This simple alarm circuit Has also a cancel button for reseting the circuit to stand-by mode again......
When a beam of light strikes the photocell, the voltage across neon lamp NE-1 rises sharply. NE-1 turns on and fires the SCR. Kl is an impulse relay whose contacts stay in position even after coil current is removed..
This circuit can be used to prevent relay contact arcing for loads up to 50 amperes. There is some delay between the time a relay coil is energized and the time the contacts close. There is also a delay between the time the coil is de-energized and the time the contacts open. For the relay used in this circuit both times are about 15 ms. The TRIAC across the relay contacts will turn on as soon as sufficient gate current is present to fire it. This occurs after switch SI is.....
The battery life and operating cost of an electric vehicle is severely affected by overdischarge of the battery. This circuit provides both warning and shutdown. An electronic switch is placed in series with the propulsion motor contactor coil. Three modes of operation are possible: When the propulsion power pack voltage is above the 63-V trip point, the electronic switch has no effect on operation. ..
When the touch-on contacts are bridged, pin 6 of Ul-b goes low, which forces its output (the set output) at pin 4 to go high. That high divides along two paths; in one path, the output is applied to pin 2 of Ul-a, which causes its output at pin 3 to go low. That low is, in turn, applied to pin 5 of Ul-b, which latches the gate in a high output state. In the other path, the output of Ul-b is used to drive Ql. When Ql turns on, U2`s internal LED lights, which turns on its.....
The load`s power factor, which is the cosine of the phase angle between the voltage across the load current, can be calculated simply with this circuit. A1:1 isolation transformer is used to prevent direct contact with the line. By properly adjusting Rr, the vector diagram of voltages Vs, Vd, and Vr forms an isosceles triangle, which simplifies the power calculation. The method basically consists of determining the power factor of the loadthe cosine of the phase angle.....
Transistor Ql remains off until the magnetic switch connected to Jl closes. When that happens, the 9 Vis connected through Rl to Ql"S base. Ql turns on, thereby charging C2 through relay Kl, which causes Kl "s contacts to close. Since the contacts connect viaJ2 to the remote control jack in the camera, which in tum connects to the camera"s shutter release, the closure of Kl"s contacts will cause the camera"s shutter to trigger. After C2 charges, Kl opens because.....
This encoder uses a single contact per key keyboard and provides all other switching function electronically. The diode between terminals 8 and 15 prevents the output going more than 1 volt negative with respect to the negative supply V-..
A flip of 51 puts the system in action. Power for the circuit is captured from the ignition switch, and circuit receives no power until the ignition switch is closed. When the camera is turned on, the capacitor C1 is charged and the emitter follower Darlington pair (formed by Q1 and Q2) are cut, so no voltage is applied to the relay (Kl), which serves as a load QL transmitter. normally open relay contacts are connected through the points of the vehicle. (At this point, the.....
The battery tester uses four transistors and two LEDs to indicate the condition of any battery you want to test. Q3 and Q4 are connected in a Darlington configuration that has extremely high gain. LED L2 lights when a small positive potential appears on the base of Q3. Transistors Ql and Q2 form a direct-coupled dc-amplifier circuit. The output of this stage drives the red LED LI. Rotary switch SI is used to select different ranges (which have been previously set by.....
The voltage reference circuit described below, is a special implementation of current source LM334. Characterized by a very small temperature coefficient metatholio output voltage and consumes only 10uA room temperature. This current fluctuates by a few uA, when the ambient temperature varies significantly. The positive rate of temperature change LM334 offset by the negative of the contact base emitter transistors has a direct thermal coupling with the integrated. To.....
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