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8051 / 8052
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Digital Signal Integrity
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4 Band Resistor
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relay driver circuit using light dependent resistor
relay driver circuit with optical isolation
relay driver board project
This article means to utilize your old PC to be come a simple controller. Many old PC like 8088 type, 8086, 80286, 80386, or even 80486 already become an obsolete systems. This board using 8-bits of LPT printer parallel data port (DP) to activate the relays. LPT printer parallel port also have 4-bits additional port (PC) which can be utilized too.
simple opto circuit for relay
switch control circuit using relay
switching control circuit using relay
car relay driver circuit
This is important in-car systems for multiple relays where the heat generated by the relay armature can be significant so any circuit that reduces the current used during normal operation will increase the reliability of the whole system. Traditional methods have used a single driver circuit per relay with consequent cost increase but relays can b
how to configure a relay to a transistor
water pump relay controller circuit schematic
By means of a Relay, employed to drive a water pump, this circuit provides automatic level control of a water reservoir or well. The shorter steel rod is the ""water high"" sensor, whereas the longer is the ""water low"" sensor. When the water level is below both sensors, IC1C output (pin #10) is low; if the water becomes in contact with the...
electronic thermostat and relay circuit
Here is a simple thermostat circuit that can be used to control a relay and supply power to a small space heater through the relay contacts. The relay contacts should be rated above the current requirements for the heater..
relay toggle circuit using a 555 timer
This 555 timer circuit toggles a relay when a button is pressed. Pins 2 and 6, the threshold and trigger inputs, are held at 1/2 the supply voltage by the two 10K resistors. When the output is high, the capacitor charges through the 100K resistor, and discharges when the output is low. When the button is pressed, the capacitor voltage is applied...
time delay relay
A time delay relay is a relay that stays on for a certain amount of time once activated. This time delay relay is made up of a simple adjustable timer circuit which controls the actual relay. The time is adjustable from 0 to about 20 seconds with the parts specified. The current capacity of the circuit is only limited by what kind of relay you...
power off time delay relay
The two circuits illustrate opening a relay contact a short time after the ignition or ligh switch is turned off. The capacitor is charged and the relay is closed when the voltage at the diode anode rises to +12 volts..
dark sensor relay switch lm741
Here is the project/schematic of LM741 dark sensor relay switch circuit. The circuit will activate the relay switch when there is no light on the surface of LDR..
flip flop relay
A very useful, easy and interesting project of a flip flop relay circuit using a 555 IC. The circuit will continously flip flop or on and off two relays one by one. ..
on off relay circuit automatic
get it on and off continuously. The circuit is using a well known NE555 timer IC which is a very famous IC due to its uses in the wide variety of electronic circuits. In this circuit this IC is connected as a astable multivibator and the 12 volt relay is derived through transistor 2N4401 which is working as a switch. The ON and OFF rate per second
relay flasher circuit
In this circuit the 555 Timer IC is connected as a astable multivibator and a 12 volt relay is derived through the pin 3 of the IC. The IC generates continues pulses at pin 3 which will activate and deactivate or flash the relay accordingly. The flashing rate per second can be controlled by the 100K variable resistor. The circuit can be operated w
temperature sensor relay switch circuit
on the desired temperature. The circuit can be used for many purposes for example switch on the fan on the desired temperature or activate emergency temperature alarm etc. The circuit can be powered by a 9 volt battery, adaptor or transformer. The two BC547B transistors are connected as a Darlington pair to increase the sensitivity or gain of the
water liquid level sensor relay switch
Here is a schematic of a simple water or liquid level sensor relay switch circuit, which can be used to switch on or off electronic appliances at the desired level of water. The circuit is ideal for automatically switch off the water pump when your water tank, pool or aquarium is filled. The circuit is very easy to build and contains only few part
Liquid/Fluid/Water/Float/Tank Level SwitchCircuit using Relay
A simple liquid level switch circuit with diagram and schematic.This can also be used as water level switch,fluid level,float level and tank level switch..
Photo relay circuit
A photo relay or light activated relay is a circuit which opens and closes the relay contacts according to the light. Here a photo diode is used to sense the light. The photo diode offers a high resistance when there is no light falling on it. Here the photo diode is connected in reverse biased condition. The only current flowing through it will...
Automatic Street Light Controller Circuit Using Relays and LDR
The circuit diagram of an Automatic Street Light Controller Circuit is explained in this post..
Lighting Consultancy and Supply
The success or failure of your lighting upgrade efforts rides on the quality of your parts and the quality of your work. It matters how carefully you route wires to avoid chafing insulation. It matters how well you solder connections (crimps and sloppy or `cold` solder joints corrode and die). It matters how well you shield added wiring from road
Interfacing Relay to Microcontroller
Microcontroller-based: Electric fan switching relay or triac
I have a project in which i will control the speed of the electric fan (220Vac, 60W, 5A max.) through the microcontroller automatically depending on..
4 time ON-OFF relay circuit
guys i need a 2 circuit the one is when power applied the timer will trigger and the relay will remain off when the timer runs out the relay will turn ..
Clap Sensitive On-Off Relay
3V Battery operated, Small portable unit This circuit was intended to activate a relay by means of a hand clap. Further claps will turn-off the relay. An..
Dual Relay Driver Board Circuit Schematic
This relay driver boosts the input impedance with a regular BC547 NPN transistor (or equivalent). Very common driver. It can drive a variety of relays, including a reed-relay. Transistor Q1and Q2 are a simple common-emitter amplifier that increases the effective sensitivity of the 12 volt relay coil about a 100 times, or in other words,
Electronic Fuse Employs A Relay
While many power supplies can be set to limit their output current to a defined level, to protect the circuit they are powering, no such protection is ava..
Handy Time Delay With Relay Output
This circuit is designed to provide delayed relay switching action at power on. The delay is a function of the time constant produced by the combination o..
Momentary Switch Teamed With Latching Relay
This circuit allows an SPST momentary pushbutton to act as a push-on push-off switch, using a DPDT latching (bi-stable) relay. It was originally intended to allow a single pushbutton switch on the dash of a vintage car to provide a latched function. The relay only draws current when it is being switched. At other times, the only current drain on t
push button relay selector
This circuit was designed for use in a hifi showroom, where a choice of speakers could be connected to a stereo amplifier for comparative purposes. It cou..
Stepper Motor Circuits
Remote Control Circuits
Direction Finder Circuits
Power Control Circuits
Motor Control Circuits
Ultrasonic distance finder circuit
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 measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
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 find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
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 circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
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 circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
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, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
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 calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
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 supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
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. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
Digital Signal Integrity
Interconnection and Timing of Digital Circuits
CMOS Circuits Tutorial