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Meter Counter Circuits
LM139 One Shot Multivibrator/Timer
One shot multivibrator circuit is also known as monostable multivibrator or timer. The function of such circuit is simply produce a pulse strobe with a fixed..
Long Interval RC Timer Using Op-Amp
With the help of high gain high impedance operational amplifier, we can build a long time delay with resistor-capacitor (RC) circuit since it allow high..
Frequency Counter and Timer
In counter mode it provides 1Hz resolution up to 100Mhz. In timer mode maximum resolution is 0. 0000001 Hz up to 1Hz. Resolution is reduced by one digit for each additional decade. Multiple frequency updates per second by employing a sliding window for calculation. In case the AVR should be programmable in circuit, a few modifications must be...
DEFROST TIMER CIRCUITS SCHEMATIC DIAGRAM
The job of this timer is to disconnect thecompressor circuit and connect a resistive heatingelement located near the evaporator atregular time intervals. The defrost heater is thermostaticallycontrolled and is used to melt any frostformation on the evaporator. The defrost heater ispermitted to operate for some length of time beforethe timer...
12 Volt Car Lamp Dimmer Circuit Design using 555 Timer
The following schematic diagram shows the 12 Volt Car Lamp Dimmer Circuit Design using 555 Timer. This circuit design can be used to dim a standard 25 watt..
741 Astable Timer
In this circuit a standard op-amp is wired as an astable multivibrator. The output is non-symmetrical but has the advantage that the timing is controlled by only 1 resistor and capacitor, in this case, the 100k variable resistor, U2 and 100u capacitor C1. Because of the high loop gain the output rise and fall times are very low, slope times better
Two Simple 24-Hour Timer Circuit Schematics
These two circuits are multi-range timers offering periods of up to 24 hours and beyond. They can be used as repeating timers - or as single-shot timers. Both circuits are essentially the same. The main difference between them is their behaviour in single-shot mode. In single-shot mode - when the preset time has elapsed - Version 1 energizes the r
A Timer That Re-Triggers At Regular Intervals
This circuit has an adjustable output timer that will re-trigger at regular intervals. The output period can be anything from a fraction of a second to half-an-hour or more - and it can be made to recur at regular intervals of anything from seconds to days and beyond. The output section is a simple Monostable Circuit. When Pin 6 of the Cmos 4001
A Repeating Timer Circuit
This circuit is based on a simple asymmetric oscillator. The length of time the relay remains energized - and the length of time it remains de-energized - are set independently. With the component values shown in the diagram - both periods are adjustable from about 1 to 30 minutes. The frequency of the Astable Oscillator depends on the value of C1
A Light Operated Repeating Timer Circuit
This circuit is very similar to Repeating Timer No. 2. However - the addition of the light dependent resistor means that the operation of this timer can be limited to the daylight hours. R7 lets you set the level of light at which the timer will stop. The type of LDR is not critical. The important thing is the voltage on pin 1. Any type of LDR sho
A Repeating Timer Circuit No.7
This timer is based on a simple Monostable Circuit. The length of time the relay remains energized - the ON period - is controlled by the values of R3 & C2. And the length of time the relay remains de-energized - the OFF period - is controlled by the values of R4 & C3. With the component values shown - periods of up to 30 minutes are available. T
Automatically Repeating Interval-Timer Circuit
The Cmos 4060 IC has two built-in inverters - at pins 9, 10 and 11. They must be wired together to form an oscillator - the output of which is at Pin 9. While the oscillator is running - Pin 9 is switching continuously from high to low and vice-versa. It`s rather like the swing of a pendulum - or the ticking of a clock. The speed at which the osci
How To Build A Sequential Timer Using A Cmos 4017
This circuit uses a Cmos 4017 decade counter to create a sequence of four separate events. The number of events in the sequence may be increased to nine or ten. And the length of each event is controlled independently. D13 causes the sequence to repeat continuously. If you leave out D13 - the sequence will run only once. I`ve used a 12-volt supply
How To Use A Cmos 4017 To Build A Sequential Timer
This circuit uses a Cmos 4017. The 4017 is a decade counter. The count starts at zero. And it advances by one - each time pin 14 is taken high. When the count reaches nine - it goes back to zero - and starts all over again. = As the count progresses - each of the output pins goes high in turn. The first is pin 3 - it represents zero. The second is
Amplifier Timer Circuit Schematic
This circuit turns-off an amplifier or any other device when a low level audio signal fed to its input is absent for 15 minutes at least. Pushing P1 the device is switched-on feeding any appliance connected to SK1. Input audio signal is boosted and squared by IC2A & IC2B and monitored by LED D4. When D4 illuminates, albeit for a very short peak, I
Frequency Meter Circuits
VU Meter 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