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Description:    A low resistance ( 0.25 - 4 ohm) continuity tester for checking soldered joints and connections. Circuit diagram  Notes:   This simple circuit uses a 741 op-amp in differential mode as a continuity tester. The voltage difference between the non-inverting and inverting inputs is amplified by the full open loop gain of the op-amp. Ignore the 470k and the 10k control for the moment, and look at the input of the op-amp. If the resistors were perfectly matched, then the voltage difference would be zero and output zero. However the use of the 470k and 10k control allows a small potential difference to be applied across the op-amp inputs and upset the balance of the circuit. This is amplified causing the op-amp output to swing to full supply voltage and light the LED's.  Setting Up and Testing:   The probes should first be connected to a resistor of value between 0.22 ohm and 4ohm. The control is adjusted until the LED's just light with the resista...

Why a lamp tester or fuse tester? Testing cables, wires, lamps… belongs to a repair job and sometimes this becomes too cumbersome since one has only two hands and too often, one has to hold the part being tester and the two probes of an ordinary continuity tester all at the same time. This fuse and lamp tester enables easy testing of lamps and fuses by using the conductivity of the human body. One of the test probes is connected to the part under test while the other probe is hel dby the normal hand. When the lamp or fuse is working properly, your eyes will glow in the dark! Just kidding :) . When the lamp or fuse is working properly, a small amount of current flows through the hand which is enough to switch the transistors and light the LED.

Generally capacitor that complement with television circuit is often leaked. Consequently spots more rugged display disturbing images running. This is not desired by the owner is not it? For those who know about electronics is certainly a problem. They will find the cause and trying to fix it. For it is not uncommon to use multitester a a search tool damage. But for those who do not have a tool that becomes an obstacle . However , for those of you who enetered last category do not sad because they can assemble their own tester. This tool is very simple but very sensitive to the leackage of a capacitor. Schematic Part List Resistor R1____________________________3K3 R2____________________________100K R3____________________________100K Capacitor C1____________________________10uF 150V C2____________________________10uF 150V Diode D1____________________________K-200 D2____________________________K-200 Lamp__________________________Fluorescent Lamp Switch_________________________On/Off How ...

IC 555 timer tester is a simple circuit that serves to test the condition of IC 555. 555 timer circuit tester, in principle, start the timer 555 in astable multivibrator mode. As an indicator of the status of the timer 555 good condition or damaged to use 2 pieces LED which will light up in a blink alternately when the timer 555 in good condition.  And only one will turn on or off all the timer 555 when the condition is broken. 555 timer circuit tester is powered using 9 Volt DC voltage source. Complete circuit tester 555 as follows. Tester schematic How to use 555 timer tester is in conjuction with IC 555 to test the existing IC socket according to the orderbutton. Then activate the power switch to begin testing the 555 timer ic. Then live we observe the LED indicators 2buah before, whether flashing alternately (good) or not blink or even die all (timer 555 damaged).

This is the simple Nicad Battery Tester Circuit Diagram.This battery tester produces Nicad battery test at a speed of 500 mA. When an endpoint 1 V (defined by the setting of R3) is resolved, pin 2 of U2 becomes low, deactivating Ql and disconnecting the test battery from the circuit. Power for U3 comes from the 12-V regulator in series with the battery being tested.   Nicad Battery Tester Circuit Diagram A clock or timer can be plugged into SI to indicate the time it takes to discharge the battery under test.

This circuit employs the popular and easy to find LM3914 IC. This kind of IC is quite very simple to drive, requires no voltage regulators (it features a built in voltage regulator) and can be powered from almost every resource. This LM3914 IC based on Simple Battery Tester is very simple to explain: Once the test switch is pushed, the Car battery voltage is supply into a high impedance voltage divider. His function is to divide 12V to 1, 25V (or lower values to reduced values). This solution is much better than enabling the internal voltage regulator set the 12V sample voltage to be feed into the internal voltage divider simply because it cannot regulate 12V if the voltage falls lower (linear regulators only step down). Simply wiring with no change, the regulator provides secure 1, 25V which can be fed into the precision internal resistor cascade to create sample voltages to the internal comparators. In any case the default establishing let you to determine voltages between 8 and 12V...

Testing was done in part 3, this last part is consist of following: Final assembly The front panel assembly can now be  lowered down onto the case. Make  sure that the three ribbon cables are  folded neatly into the space above the  lower PCB and not caught between the  edges of the case or lid.  Fasten the case together with four  M4 screws into the corner holes, then  fit the knobs to the rotary switch and  the pot and the assembly is complete.  Testing the HV crowbar It’s now necessary to check that the HV crowbar circuit is working correctly. To do this, power up the unit, wait a few seconds and then press the Menu Select button. You will get a display like this: Device to Test:▲ 1:Diode/Zener▼ Press Enter and then the Up button. The display will then show: Test parameter:▲ Irev(OPV)▼ Press Enter again. Set the Device Operating Voltage to 25V, using the right-hand knob. Then press the Test On/Off button to start the test. Now careful...

Like all its counter Parts, this network wiring tester comprises two elements, a transmitter unit, powered and fitted at the network start point, and a receiver unit, passive, which can be moved around from socket to socket. Each of these units carries eight LEDS, identically labelled 1 to 8. By operating a push-button in manual mode, or using a clock in automatic, the eight LEDs light up in sequence on the transmitter unit and obviously they should do the same on the receiver unit. In this way, just by watching the LED lighting cycle on the receiver unit, you can immediately spot any crossed wires, as well as any open circuits (the relevant LED never lights up) or shorts (two or more LEDs light at the same time). Circuit diagram : Network Wiring Tester Circuit Diagram The transmitter unit circuit is simple' The Schmitt-input NAND gate lCl.A is wired as a multi-vibrator, whose speed can be adjusted using Pl, while lCl.B is wired as a simple debounce circuit for button 52, used...

INTRODUCTION TO SIMPLE CONTINUITY TESTER CIRCUIT Continuity Tester is an important tool while you wiring up a circuit, repairing an electronic device and for any other electronic related Operations. Now i will assist you on making this SIMPLE CONTINUITY TESTER CIRCUIT .... This circuit have an advantage over ordinary CONTINUITY testing Device, usually we are using multimeter to check the continuity of a circuit. It is not suitable to check the continuity of a circuit with high Impedence or resistance like Transformer, Capacitors, and even for high value Resistors. This circuit helps you to determine whether the device or electronic component is working fine And by using this SIMPLE CONTINUITY TESTER you can repair any damaged electronic devices easily [By identifying the actual fault of the device]. CIRCUIT DIAGRAM OF SIMPLE CONTINUITY TESTER WORKING OF SIMPLE CONTINUITY TESTER The circuit uses only an NPN transistor(BC 107), with a Current Limiting Resistor and an Indicator LED. The c...