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Meter Counter Circuits
plant soil moisture tester circuit
A very simple and useful project of soil moisture circuit. The circuit is using only four components and a 3 volt battery. The circuit will detect if there is water in the soil of any plant and light up the LED. The resistor R2 is a potentiometer to adjust the level on which you want to make the LED on.
remote tester circuit
Here is a remote tester circuit or remote checker circuit which can be used to test TV and other remote controls. The circuit is very simple using only few components. The infrared sensor used in the circuit is TSOP1738. When the IR waves received by the infrared sensor it will make the
telephone line tester
A very simple and easy telephone line tester circuit or telephone line checker circuit which can be used for testing telephone lines. ..
transistor tester circuit
This is a very simple transistor tester circuit the circuit can be used to test NPN and PNP transistors. The voltage source is a 6V power supply which is 230V AC to 6V step down transformer. It is essential to put the transistor leads in right direction like transistor emitter to circuit emitter where (E) is marked transistor base to circuit base
Water quality checker project simple circuit diagram
How to measure water purity How to test water quality using a simple electronics project You can perform water purity measurement and water quality analysis using this water purity checker circuit. This circuit is built around a simple LDR (Light Depended Resistor) and some discrete components. The most attractive feature of our water purity tes
555 Tester circuit
Here the NE555 is wired as an astable multivibrator. When the push button switch S1 is pressed the LEDs D1 & D2 will flash alternatively. That is when output is high D2 will glow & when output is low D3 will glow. The rate of flashing will depend on components R1, R2 & C1. When push button S1 is pressed, C1 will start charging through R1&R2....
Humidity Tester Circuit Using Sensor
A simple humidity tester circuit using just a LED, transistor, and a few resistors is explaind with a neat circuit schematic..
LED based transistor tester
Here is the circuit of a very simple transistor tester which used two LEDs for displaying the condition of a transistor. Both PNP as well as NPN transistors can be tested using this circuit. Quad 2 input CMOS NAND gate IC CD4011B is the heart of the circuit. Out of the four NAND gates inside the IC, only three are used here and they are used as NO
Quartz crystal tester circuit
This a very simple and inexpensive circuit that can be used to test quartz crystals. Here a Colpitts oscillator is wired used the transistor T1. When the crystal is connected between terminals A and B the circuit will produce high frequency oscillation. The oscillations will be generated only if the crystal is a good one. The diode OA91 will...
Remote Control Tester Circuit using Infra red sensor IC TSOP 1738
A simple remote control tester circuit with diagram and schematic using infra red sensor IC TSOP1738. An LED will blink when IR waves falls on it which indicates remote control functioning..
Sense of Time tester circuit
When S2 is ON, the circuit here operates as an astable multi vibrator and the LED is lit for about o. 1sec, flasing every 1. 5 seconds. Since the human reaction time is more than this, you cannot catch it once it is seen o, by pressing S1. If your sense of time interval is good, and you press S1 with in that 0. 1 sec, the discharging of C1 stops...
Transistor Tester to test Hfe and working of NPN and PNP Transistors
Here is a very simple circuit that can be used to check the hfe of transistors. Both PNP and NPN transistors can be checked using this circuit. Hfe as high as 1000 can be measured by using this circuit. The circuit is based on two constant current sources build around transistors Q1 and Q2. The Q1 is a PNP transistor and the constant current...
Wireless mains voltage tester
This circuit can be used to test whether mains voltage is present or not without having electric contact with mains line. The CMOS IC CD4033 is the heart of this circuit. The CD4033 consists of a 5 stage decade Johnson counter and an output decoder for converting the Johnson code to a 7 segment decoded output for driving 7 segment LED display. A 1
Zener diode tester
Here is a very simple circuit that can be used for testing Zener diodes. The IC1 NE555 is wired as an astable multivibrator and the output of the IC is stepped up to a high voltage AC using the transformer T1. The unloaded AC voltage will be around 120V. The AC voltage is rectified by the diode D1 and filtered by the capacitor C3. This voltage...
This circuit can measure both small signal hfe and DC current gain hFE of a low to medium power power transistor..
Multi Wire Cable Tester
Is a capable tube tester, yet its use scenarios can be multiplied with only modest efforts invested in understanding its schematic, regimes, and ways to add new regimes. Eico 666 is capable tester, known to be able to supply voltages and currents adequate for most tubes. It performs emission/conducance tests as well as leakage tests. The
Tube Tester for any budget
Car & Motorcycle Battery Tester
Most of the time a charged lead-acid battery and a power inverter would be used to ensure a smoothly organised holiday where ideally the missus and the children cheerfully use their electric and electronic gear! With rechargeable lead-acid batteries it`s invariably useful if not essential to determine whether the power source you`re hauling...
Transistor Tester Identifies Terminals Power
The simple transistor tester in Figure 1 lets you identify the type of transistor, and it helps in detecting a transistor`s emitter, collector, and base..
automotive sensor design with design checking and self assessment
Inductor saturation tester alternative route to dump the excess energy
Yes, it does charge the inductor again. Diodes are a good that they will not charge the inductor back but of course dissipate fair amount of instantaneous power due to the forward voltage drop. One way would be to monitor the current and stop driving those fets when the current turns negative, but I guess that is quite complex solution. I think...
12/24/48 V D.C. Tester
The present tester is intended primarily for testing the 24 V electrical circuits found on most pleasure craft. However, if the resistors are given different values, the circuit may, of course, be used for other voltage ranges. For 12 V, the value of the resistors should be 1. 2 k, and for 48 V, 4. 7 k. The tester should be connected to the +ve an
4-20mA Current Loop Tester
This design will interest technicians who work on pneumatically operated valves and other 4-20mA current loop controlled devices. Although 4-20mA signal i..
A Very Simple LED Tester
This simple LED tester consists of a current source with a potentiometer that can be used to adjust the current. The current source is implemented using a type TL081 opamp. The output current of the opamp flows through the diode and R2. The voltage drop across R2 is fed back to the inverting input and compared with the reference voltage, which is
Battery Tester Circuit Schematic
Is the battery empty, or is there something wrong with the device? That s always a difficult question when your walkman or some other battery-powered devi..
Car and Motorcycle Battery Tester
Going camping nowadays involves taking lots of electronic equipment whether for day to day running or for fun and entertainment. Most of the time a charge..
Components Voltage Tester Circuit Schematic
This simple circuit tests speakers, microphones, transformers and voltage. It`s basically a very low frequency oscillator that produces extremely short fruity` pulses. The type of sound produced is very easy to hear and to determine the precise direction it is coming from, thus making it ideal for checking the phasing in multiple speaker installat
Computer Data Cable Tester
You don t need access to fancy test gear to check and fault-find computer data cables. Instead, this simple device will give a quick indication of the sta..
Infrared Remote Control Tester
The infrared detector module (GP1U52X) (Radio Shack 276-137) provides a 5 volt TTL pulse train corresponding to the digital code to the button of the remote control. In the lower circuit, the module output normally low a signal and a positive going pulse train whena signal is present. Other detector modules that an inverted output is in the...
IR Remote Control Tester
This small circuit is ideal for checking the basic operation of an infrared remote control unit. The circuit is based on the brilliantly simple idea of connecting a piezo buzzer directly to an IR receiver IC. This method is almost as simple as connecting a photodiode directly to the input of an oscilloscope, but has the advantage that no oscillosc
Liquid-Crystal Display (LCD) Tester
A segment may be tested by applying an alternating voltage of a few volts across it. Note that the application of a direct voltage will damage the display irreversibly: the resulting current will remove the tracks. The alternating voltage should contain not even a tiny direct voltage component. An alternating current also removes part of the...
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...
Digital Signal Integrity
Interconnection and Timing of Digital Circuits
CMOS Circuits Tutorial