Safety Circuits
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This project is an electronic lock with many combinations that you can easily change and opens only with the correct combination of four consecutive numbers. The big advantage of the electronic lock is that the four numbers must be entered in the correct.... -
That circuit protects the overdriven signals going into an amplifier. Instead of a zener diode we use a transistor. That way we ensure that the above the ordinary input voltages ( 1 volt r.m.s.) can be acheaved without distortion. Also the use of a.... -
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
In essence, the circuit is nothing more than an auto ignition coil and a set of points which accomplishes the same thing. A pulsing circuit made from a single CMOS NOR integrated circuit (Ul), opens and closes the relay contacts to simulate the action of the.... -
The silicon controlled rectifier (SCR) is rated to handle at least the current of the power supply. It is connected in parallel across the 12 V dc output lines, but remains inert until a voltage appears at the gate terminal. This triggering voltage is.... -
The push button and potentiometer initiate a time delay that turns a light on then automatically turns it off again after a predetermined time. The potentiometer can be set for a delay of a few seconds to just under three minutes. When the push-button switch.... -
This circuit checks the reliability of appliances so that the equipment may be used safely. The test circuit must be plugged into a properly wired three terminal wall outlet. When a two-lead or three-lead appliance is plugged into circuit outlet SOI, neon.... -
Industrial applications sometimes require that power be only briefly applied to a load following the closure of a switch, such as a microswitch or foot switch. The load could be a heating element for use in sealing plastic bags, a de motor that is indexed.... -
The spark developed by the circuit is suitable for a gas ignitor. Capacitor Cl is charged through Rl and Dl toward peak line voltage. C2 is simultaneously being charged at a slower rate through R5. When the charge on C2 is sufficient.to trigger the PUT,.... -
To avoid grief when using 12-V power supplies with mobile transceivers, especially when there is a short -circuit failure of the series pass transistor, crowbar circuits provide protection by clamping the power line and blowing the fuse within microseconds.... -
This circuit uses a type 741 op amp as a voltage comparator. One input of the 7.41 is connected to a reference voltage (a 12-V battery) through a resistor voltage divider. The potential at the noninverting input of the 741 is approximately 3 V. The.... -
The adjustable circuit breaker responds in 0.02 sunder all conditions-provided you select a fast relay for Kl. For moderate overload conditions, it"s preferable to use the fuse or the fast-acting breaker. Toroid transformer Tl senses ac load current and.... -
This circuit protects expensive portable equipment against all types of improper hookups and environmental hazards that could cause an overvoltage condition. It operates very quickly and does not latchup, that is, it recovers when the overvoltage condition.... -
These two circuits are SSB generators. One uses a crystal filter by KVG Electronics at 9 MHz, the other uses a 455-kHz mecha.. -
Most of the transistors in this speaker protector function as switches. Normally, Q4, Q5, and K1 are on and the speakers are connected to the amplifier. However, if a large dc voltage appears at an amplifier output, either Q3, or Ql and Q2 turn on, biasing.... -
Basically, this circuit is an adjustable electronic circuit breaker, containing a toroidal transformer that senses 60-Hz load current. Tl has a two-turn winding for primary, and 100 turns of #30 gauge wire for the secondary. A high-low range switch selects.... -
A speaker system can be protected against amplifier failure when dc voltages (on speaker line a-b) arc sensed by the circuit. Either positive or negative dc voltages are sensed. A relay opens in this case, removing the dc from the speakers... -
When testing a circuit, a source of voltage that is variable and has overvoltage shutdown is veiy useful. In this circuit, Rl is adjusted to 1 to 2 V below the eventual shutdown threshold. R2 sets the trip voltage. When this voltage is reached, the circuit.... -
The ear protector is actually a peak audio-detector/shutdown circuit that disables the amplifier through its chip-disable input when the output volume of an amplifier reaches the set level. The circuit, although intended for the MC34119 amplifier,.. -
Transistors Ql, Q2, and Q3 monitor the two outputs of the stereo amplifier. If the offsets exceed 2 V, Q7 is turned off, which turns off Q8 and the normally on relay. Diodes D2 and D5, together with Q4, provide a mains voltage monitor. As soon as the ac.... -
Any good power transistor can be used in this circuit. The base resistor should be adjusted to obtain a pulse rate of about 50 pulses per minute. The range of values shown can go from 10 pulses to 100 pulses per minute. The single fence wire must be.... -
A touch-sensing circuit keeps the high-voltage generator cut off until something touches the fence wire. Contact with the fence sensing circuit wire starts the high-voltage generator which applies a series of 500 microsecond pulses at approximately 300 volts.... -
Using Wuxi love core Microelectronics Co., Ltd. H1.9811 single Chan flash control integrated road barricades made of flashing warning lights, HL9811.. -
The Generator cell must have reasonable surface area on the Plates to generate a reasonable amount of Hydrogen/Oxygen. And a Typical construction would use Stainless Steel for the Electrodes to prevent them from being Quickly eaten away... -
This project gives you a fingerprint based attendance system with 8051 microcontroller. The SM630 fingerprint module is used for fingerprint matching. It can store a max of 768 fingerprints. The admin can add/delete records from the PC through the VB.... -
This circuit features automatic Exit/Entry delays, timed Bell Cut-off and System Reset. It has provision for normally open and normally closed switches and will accommodate the usual input devices such as Foil Tape, Pressure Mats, Magnetic Reed Contacts,.... -
The thermistor used has a resistance of 15k at 25 degrees and 45k at 0 degrees Celsius. A suitable bead type thermistor can be found in the Maplin catalogue. The 100k pot allows this circuit to trigger over a wide range of temperatures. If using a different.... -
The gain control element is a Light Dependent Resistor (LDR). These are blessed with a few very useful features for our purposes, one of which is low distortion even at quite high signal levels. Being light activated, all we need is a LED to provide.... -
Repell those repugnent insects from your Garden this Summer with this insect repellant circuit. Designed by Graham Maynard the circuitry consists of a phase locked loop (CMOS 4047) wired as a 22KHz oscillator. The output is amplified by a pair of.... -
A fast electronic fuse designed to operate on 230V AC with an adjustable trip current. When the current through the load exceeds a level determined by the position of the wiper on the 1k wire-wound pot, this circuit cuts off the load immediately. If S1 is.... -
Safety devices like fuses provide protection against excess current, but do nothing for transients and short duration spikes of high voltahe on the power supply lines.This circuit uses the "crowbar" method and provides fast protection against transient.... -
This circuit has proved very useful in keeping away from a terrace or a porch some bats and other nocturnal animals. You can use it for similar or different purposes. The lamp illuminates for a 4-5 seconds delay and stays off about one minute and 15 seconds.....
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New Circuits
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
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The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is.... -
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to.... -
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This.... -
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the.... -
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,.... -
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the.... -
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power.... -
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
Popular Circuits
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This circuit protects expensive portable equipment against all types of improper hookups and...
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The first one I bought for US$ 3. It has an internal rectifier, and even after I dug it out of...
The liquid detector is a detector with liquid alternating voltage and can be built using some...