Vacuum Tubes Valves
Musical & effects
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Human Sensing Circuits
RF & Radiation
Optical Sensing Circuits
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AC to DC & DC to DC
Solar Cell Circuits
Micro Power Circuits
Switching Power Supplies
Light Laser LED
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Data Bus Circuits
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RF Converter Circuits
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voltage to frequency
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Video Wall circuits
TV Video Circuits
Motor Control Circuits
8051 / 8052
PCB CAD Software
Car bike Circuits
555 Timer Circuits
Remote Control Toy
H Bridge Circuit
DIY HV Variable Cap
DIY PMA alternator
Interconnection & Timing
Digital Signal Integrity
Digital & Bipolars
Sensors & Detectors
Regulated Power Supply
4 Band Resistor
5 Band resistor
6 Band resistor
Time to start reversing relay control circuit
Circuit shown in Figure 3-162. in graph. SBi is forward the start button, SBz to reverse the start button, SB3 for the stop button. Start switching resistance levels are contro
Auto-voltage starting time relay control circuit
Circuit shown in Figure 3-49. The circuit autotransformer out of operation by the time relay KT control. KT delay time is equal to the motor start-up time. Circuit shown in Fig
DC relay delayed release circuit 2 b
Circuit shown in Figure 6-24. Both ends of the relay coil in parallel with a resistor Rf or auxiliary diode VD, is equivalent to power after a short circuit coil core increase,
Video Operated Relay
Many Video Operated Relay (VOR) circuits have been published in recent years for use in connection with ATV repeater controllers or automatic videotape logging systems. Unfortunately, many of these circuits fail to properly detect certain video signals depending on their signal-to-noise ratio or their picture content. Most designs rely on using...
Photo Light with Relay
The circuit below uses a CMOS dual D flip flop (CD4013) to toggle a relay or other load with a momentary push button. Several push buttons can be wired in parallel to control the relay from multiple locations.
Circuit removes relay-contact bounce
Contact bounce in those relays, however, can prove troublesome to downstream circuitry. One approach to contact bounce combines a relay with a hot-swap controller. Such controllers are increasingly popular as the means for switching system components without shutting down the system power.
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...
Time-delay relay & proximity control
The design uses a proximity detector rather than a pushbutton switch to eliminate the need to mount and wire any equipment outdoors. The circuit worked well in this application and other applications.
Time-delay relay reduces inrush current
In contrast, the circuit in Figure 1 physically inserts a resistor in series with the load to limit the inrush current and then short-circuits the resistor after a time delay. You can adapt the circuit to any size load by suitably selecting the series resistor and the relay-contact rating.
Light/Dark Detector relay
This handy little circuit can tell the difference between darkness and light, making it very useful for switching on and off signs, porch lights or other things when it gets dark or light.
12V Relay on 6V power supply
This circuit allows a 12v relay to operate on a 6v or 9v supply. Most 12v relays need about 12v to "pull-in" but will "hold" on about 6v. The 220u charges via the 2k2 and bottom diode. When an input above 1.5v is applied to the input of the circuit, both transistors are turned ON and the 5v across the electrolytic causes the negative end of the...
Mains Detector Relay with CD4017
This circuit is operating the room illuminates. The basic component of the circuit is a IC1 (CD4017). Push buttons room are connected by normally wired to the circuit. All circuit is separately by optocoupler, which means that the circuit is immune to electrical noise that can come on cable that connects with push buttons. First any button push...
Solid State Relay
Solid State Relay Switch is a simple kit which will help you control (ON / OFF) a single high power circuit from a low power drive. Load - 24 to 240 VAC @ 500 W. Trigger voltage - 2 to 5 VDC (TTL) @ 10 mA. Input isolated with use of Optocoupler. Power Battery Terminal (PBT) for easy input 230 VAC mains and load connection. Terminal pins for...
433 MHz 4-ch receiver with relay output transmitter
Momentary output : One of the relays RE1...RE4 is ON as long as CH1---CH4 is pressed from transmitter. Latch output: when one of channels CH1...CH4 is pressed from transmitter RE1...RE4 are ON as long as other CH is pressed from transmitter. Valid transmission indicator: LED is always on when reciever recieves valid data.
Timer switch circuit
A 100 second delayed turn ON relay RL1 switch, if plug power +12V in circuit. In Fig.2 see a two range 6-60 second and 1-10 minute auto turn off relay timer circuit, with 555.
under?-over voltage detector
In Fig.1 A precision DC under?voltage relay switch. The opamp is wind as a voltage comparator, with a reference voltage applied to pin 2 and the test voltage applied to pin 3: the relay turns on when the pin 3 voltage exceeds that of pin 2. The circuit can be made to trip at any voltage in excess of 5 volts by suitable choice of R1 value. In...
Touch Switch with 555
The modern mechanic switches are improved concerning of old technology. We need however many times to replacement some old switch or to check currents bigger than the durability of certain switches or simple we need something with modern appearance. For he and different reasons is essential the up circuit. He is simple in the manufacture and...
Touch Switch with relay
A simple circuit with which we have the possibility opening and closing the RL1 contacts. He becomes touching a small metal surface. Clue of situation that is found RL1, is become by the Led D3. The supply of circuit is +12V, the IC1 is supplied with 3.9V fall of voltage that is ensured by combination R5 and zener D2. For more good restoration...
Signal and Tone Activated Relay Switch
In the Fig.1, exist a circuit, which is a sensitive switch that corresponds in AC signals of input, for signals above 5mV. Corresponds in all the signals from 50 HZ until 3KHZ, region in which found the human voice. The RV1 is regulated so much what RL1 it?s in situation OFF, when the input is it has null signal. In the Fig.2, exist a band -...
Temperature limit Relay
This circuit, is basically a resistance ? sensing window switch, except that the ?resistor? takes the form of an NTC thermistor and the circuit thus responds to temperature. TH1 must have a resistance in the range 500ohm - 9Kohm. RV1 is used to set half ? supply volts on the RV1 ? TH1 junction at the ?mean? temperature.
8 input Relays circuit
It is the essential continuity of circuits Sel 8 Sources and Up/Down Sel 8 Sources, but can work and autonomously, collaborating with any suitable circuit of control. The Relay 1-8 can be 6-24v DC. For current of collector of transistors Q1-8, bigger the 10 mA, it is better we use BD 139 or BD 679 with R 1-8 is 15K?.
8 way electronic selector / switch
The Elect. Sel. 8 is a simple circuit, with a choice of 8 sources of any sort ,of 8 independent switches. Each switch corresponding with a relay for example the switch S1 activates the RL1 e.t.c. The uses of the circuit are quite a few, choice of entrances in a sound amplifier, choice of command, in a digital circuit etc. In each entrance a...
Electronic 10 way Selector Relays
This is a circuit for alternative sources selection. It combines mechanical selection using a rotating switch S1, the electronic drive of the relays RL 1-10 and also the optical indication of the selection by the Display DSP1. The function is based on the connection of the mechanical selections into 4 Bit (BCD) code. It is managed by the proper...
Voltage window switch
A voltage window switch is in practice the basic lower window limit of this circuit is roughly 3V and the upper limit is 9V. The window range can be extended by fitting a suitable range
Emergency Pump Control with 555
A simple Sump Pump Control Circuit using NE555.
Light/dark relay switch
This kit is the most basic, practical circuit to build using an LDR to turn on a relay. The two transistors connected as a Darlington pair give the circuit enough sensitivity, while the trimpot give sensitivity adjustment. The switching point of the relay is dependent on the supply voltage and temperature. This circuit is satisfactory if...
Advanced LED Flasher with 555
This circuit uses three easily available 555 timer ICs. All three work as astable multivibrators. The first 555 has an on period and off period equal to 1 sec. This IC controls the on/ off periods of the other 2 555s which are used to flash two bulbs through the relay contacts. The flashing occurs at a rate of 4 flashes per second. The diodes...
Optical toggle switch with 4027
Using dual flip-flop IC CD4027 employ a 555 based monostable circuit to supply input clock pulses. The circuit described here obviates this requirement. One of the two flip-flops within IC CD4027 itself acts as square wave shaper.
Disco Smoke controller
When the power is connected to the circuit by turning on SW2, RELAY1 get energized for the time it get for it to load C3 through R1 and R3. After that the relay get de-energized, C3 gets discharged through R2 and R4. The setting of R2 determines the discharge time which can be up to 1 minute. After C3 is discharged, the releay is activated. C3...
amplifier delay output relay
This is a simple circuit which I built to one of my audio amplifier projects to control the speaker output relay. The purpose of this circuit is to control the relay which turns on the speaker output relay in the audio amplifier. The idea of the circuit is wait around 5 seconds ofter the power up until the spakers are switched to the amplfier...
Current sensing relay
It operates by PWM (Pulse Width Modulation) - well, actually by PFM - Pulse Frequency Modulation. At power up, C1 charges up via D1 and R1. R2 will conduct, pulling the base of the emitter follower, Tr2, up and feeding gate voltage to the MOSFET. Tr4. Clearly the circuits in an analogue region during power-up, but as this is intended for use on...
Load detector Mains Switch
This circuit will automatically switch on several mains-powered "slave" loads when a "master" load is turned on. For example, it will switch on the amplifier and CD player in a stereo system when the receiver is turned on. It works by sensing the current draw of the "master" device through a low value high wattage resistor using a comparator....
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...
DIY HV Variable Capacitor
DIY PMA Alternator Plans
Digital Signal Integrity