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Solar Cell Circuits
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Switching Power Supplies
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Data Bus Circuits
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Video Wall circuits
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8051 / 8052
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555 Timer Circuits
Remote Control Toy
H Bridge Circuit
Interconnection & Timing
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Transmitters & Receivers
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4 Band Resistor
5 Band resistor
6 Band resistor
Rain alarm schematic circuit diagram
FIG. 1 is a circuit diagram of it, it is in the audio circuit from the resistance between the two leads to a probe to rain alarm. Fig. 2 with CCL to make a probe connected to t
Fire Alarm schematic design
Explanation Here is a simple fire alarm circuit based on an LDR fire detection sensor. Smoke generated during circuit generates an audible alarm, fire smoke in case of fire. Al
Door alarm circuit with a time of recognition NE555
Door alarm here with a time recognition, the owner opened the door is normally open the door, open the door to complete the action within the general 30s, so it does not alarm,
Break burglar alarm circuit II
Ding for the circuit principle: care, vs SCR trigger grounded, it is in the off state. When someone leads A burglar broke, the SCR trigger end to give a trigger voltage is turn
The circuit generates a warble-tone alarm signal that simulates the sound of a British police siren. IC1 is wired as an alarm generator and IC2 is wired as a 1 Hz astable multivibrator. The output of IC2 is used to frequency modulate IC1 via R5.
The single-chip, burglar -alarm circuit shown uses a dual 556 timer, draws 10 mA of standby current, and generates a pulsing alarm signal that conserves battery energy. Once activated, the alarm wilLremain on, independent of the subsequent state of any of the sensors. The sensors support both deferred and immediate-action modes. You can...
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...
The heart of the circuit is a 555 oscillator /timer, Ul, configured for monostable operation. The output of Ul at pin 3 is tied to the gate of SCRl. As long as Sl-S5, which are connected to the trigger input of Ul, are open, the circuit remains in the ready state, and does not trigger SCRl into conduction. Because the relay is not energized,...
The tracer, consisting of both a transmitter and receiver, is designed to follow a closed-loop wire or cable system. It follows an induced voltage path created by feeding a low-current, audio-frequency signal through the cable. When the pick-up coils come within close proximity of the current -carrying cable, a small voltage is generated...
Burglar Alarm With Timed Shutoff
When SI (sensor) is closed, power is applied to U2, a dual timer. After a time determined by C2, CI is ene
Home Security System
This alarm circuit activates when SI through S5 are activated. This lights LED1 and activates Ql via IC1C and IC1D. RY
Warble Alarm Circuit
This circuit uses a 556 to first generate a low frequency square wave, that is modulated to produce two alternate tones of about 400 and 500 Hz. Circuit generates warble alarm of European emergency vehicles.
Audio Alarm Circuit
In the circuit, U1 amplifies the audio picked up by the condenser microphone. Resistor Rl limits current, while R2 and R3 center the output of the amplifier to %B+ to allow a single-ended supply to be used. Diodes D1 and D2 rectify the output of Ul, and C3 filters the resulting pulsing dc. Thus, a dc voltage that is proportional to the ambient...
Piezoelectric Alarm Circuit
The alarm uses a fixed-frequency piezoelectric buzzer in conjunction with the cadmium-sulfide (CDS) cell and the two-transistor circuit to provide a unique effect. Whenever light reaches the CDS photo-electric cell, the alarm is silent. But when no light strikes the cell, transistor Ql turns on, and the circuit emits a high-pitched tone.The...
Burglar Chaser Circuit
The burglar chaser makes a great accessory for any alarm system. It creates brilliant flashes of white light and a loud, irritating sound from a metal horn buzzer. Transformer T1 is connected to Ql, Rl, and R2 to form a blocking oscillator. This creates a 6-Vac signal on the primary of Tl. Because of Tl`s large ratio of turns from primary to...
Carrier-Current Baby-Alert Transmitter Circuit
The baby-alert transmitter is built around an LM324 quad op amp (Ul), two LMC555CM CMOS oscillator/timers (U2 and U3), and a few support components. The transmitter sends a signal on receipt of a sound at MIC1.
Carrier-Current Baby-Alert Receiver Circuit
The baby-alert receiver is comprised of three transistors: Q2, which is configured as a high-gain linear amplifier; Q3, which serves as both an amplifier and detector; and Q4. which is essentially used as a switch; and a few additional components.
Flash Signal Alarm Circuit
This circuit is useful if you need a low-energy flashing alarm. The 200 to 400-dc supply should have enough internal resistance to charge the 0.5 capacitor between flashes, about 2 or 3 time constants, which means about 500 kQ to 1 for a 1-s rate.
Proximity Alarm I Circuit
IC1 contains several oscillators and an amplifier. The low-frequency audio-signal oscillator is used to supply an input to the amplifier. That signal is the audio tone that is amplified, then supplied to the speaker by the amplifier. The high-frequency oscillator is purposely set to be very unstable. It is dormant or off` until the...
5V Dial Tone Circuit Circuit
This circuit uses inexpensive, common components to generate a precise dial tone for phone applications (see the figure). Ul (an Intel 82C54 timer-counter) generates 350 and 440Hz square waves that are filtered by Rl/Cl and R,JC2, and mixed together by resistors R2 and R4. An operational amplifier configured as a 395-Hz, Sallen-Key,...
Simple House Alarm circuit
This house alarm circuit has open and closed loop sensor and has self shutdown function. The delay after trigering can be adjusted from 1 minute to 12. The delay before trigering is 13 seconds. Offcourse all this timmings can be change with litle changes to few passive parts.
This inexpensive dc supply-voltage monitor sounds a warning when the voltage falls below a preset value. It is ideal for monitoring rechargeable batteries since it draws only a few microamperes when not sounding. The voltage at which the alarm sounds is determined by the zener diode. When the voltage falls below the zener voltage, the alarm...
This circuit simulates the sound of an American police siren. IC2 is wired as a low frequency astable that has a cycling period of about 6 seconds. The slowly varying ramp waveform on Cl is fed to pnp emitter follower Ql, and is then used to frequency modulate alarm generator IC1 via R6. IC1 has a natural center frequency of about 800Hz.
Timer with alarm
The circuit has two ranges: 10 sees to 5 mins and 1 min to 80 mins. It can be powered by a 9-V battery. With the LED connected as shown a reasonable frequency of flashing occurs throughout the range of operation.
Clever Car alarm circuit
When this car alarm circuit is activated it stays activated for 80 seconds. It has 15 seconds delay for the driver to enter and deactivate. and All timmings can be altered easilly...
One circuit alarm phase
3-phase power, would endanger the electrical equipment (especially asynchronous motor) security, in order to detect phase failure, it can be made with a broken alarm. Circuit s
Portable alcohol detector alarm circuit
Circuit works: QM-NJ9 is alcohol sensor. QM-NJ9 contact after the odor of alcohol, the resistance value A, B between the reduced
The circuit has a built-in, self-arming feature. The driver turns off the ignition, presses the arm button on theComputalarm, and leaves the car. Within 20 seconds, the alarm arms itselfâ€”all automatically! The circuit will then detect the opening of any monitored door, the trunk lid, or the hood on the car. Once activated, the circuit remains...
Gas stove flame alarm circuit
The circuit shown is the second natural gas (gas) stove flame alarm. After the gas stove ignited normal combustion, close the power switch S. Photoresistor RG due
Mains voltage bidirectional limit alarm protection circuit diagram
When the alarm protection can be higher or lower than the predetermined value in the mains voltage, sound and light alarm,
Power disconnection alarm circuit diagram
Circuit operation principle of the device shown in Figure 13. When the barbed wire Fe intact, LSE's O, feet collusion between its pin output high,
Multi power failure alarm circuit
Circuit works: This is an AC blown fuse alarm. When BX is not when blown, 220 V AC voltage through a VD1 VD4 bridge rectifier, R1 limiting buck, after DW 6V DC
Surveillance Bug Circuits
Construction of 50Watt 8Ω two-way Hi-Fi Speakers
The presented speakers are distinguished for their small dimensions and their extraordinary sound. Our home space is often limited and prohibitive for large speakers. This limitation does not mean that we will stay without high Sound Quality. Its design is simple, low cost and is easy to construct. Speaker types are too many and are designed in...
GSM modem circuit with Wavecom WMOi3
Modems are devices that connect either remote devices to a computer, or two or more computers to each other. Their connection is usually wired. The GSM modem we present is wireless. It can connect two computers, a computer with the internet or even be the central unit for a data acquisition system. Generally the construction is a GSM phone...
1W UHF Linear Amplifier with BLW33
This circuit is an amplifier for small transmitters operating in the UHF band, specifically in the 450-800MHz range. The amplifier works in class A and we used the well-known Philips BLW33 transistor for its manufacture. The construction, although simple, can be said to be quite critical due to the high frequency singularity. To achieve this, a...
8W Amplifier with TDA2003 circuit
Many times a small amplifier is needed to meet the needs of small spaces. This amplifier can be either mono or stereo, with this circuitry you can comfortably drive two small speakers. To build the amplifier you do not need anything but a few materials and a small power supply. The power of the amplifier, although low power, will solve many...
FM Linear Amplifier 400mW
This amplifier is intended for amplifying low signals from oscillators in the FM band. It does not have frequency regulators with variable capacitors and coils, it has a wide range and moderate power capable of driving several linear amplifiers. The whole construction is based on the two low-power 2N4427 transistors, which are designed for the...
50 Watt Hi-Fi power amplifier circuit
SGS Thomson's integrated TDA7294 is a high-frequency acoustic power amplifier, with true high-precision specifications, suited for all relevant applications. Its main feature is much higher output power than is usual in amplifiers with similar distortion performance. According to its manufacturer, the output stage of this 15-pin integrated can...
RF Remote Control Switch Rx-Tx circuits
This circuit consists of a 2048 radio remote control transmitter and the corresponding wireless receiver with very high reception sensitivity and low consumption. The combination of the two above gives a high-reliability remote control, ideal for security systems, alarms, automation, etc. At home, in the car and elsewhere. Using the wireless...
0-30V Lab Variable Power Supply
At the left side (input AC) goes the secondary of a 220 volt (primary) 18 Volt (secondary) / 3 Ampere mains transformer. The alternating voltage of 18 volts from its secondary transformer is rectified by the diodes D1, D2, D3 and D4, which are connected to a bridge arrangement and make a double rectifier. The pulse from the bridge exit is...
Ultra High Sensitivity Metal Detector Circuit
This circuit is a metal detector capable of detecting large metallic objects. at a depth of 2m to 3m. It depends on the size of the object, and often on the type of soil. Construction is very easy to implement even for a beginner. The necessary components are easy to find everywhere. This detector has the ability to detect a gold coin of 20mm...
Digital Signal Integrity
Interconnection and Timing of Digital Circuits
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