Elektrokit

Shankar Nagar, Nagpur, Maharashtra

Infrared Remote Tester is required to test our TV remotes. This is a simple, low cost and easy to construct Infrared Remote Tester. The tester is build around an easily available infrared receiver module. We are engaged in to manufacturing and supplying Infrared Remote Tester nationwide.

About the Circuit :Normally data output pin 3 of IR receiver module is at a high level and as such driver transistor T1 is in cut off state. Whenever the IR receiver module receives a valid (modulated) infrared signal, its data output pin goes low in synchronism with the received infrared bursts. As a result T1 conducts during negative pulse period and the LED blinks to indicate reception of signals from the remote such as TV remote control. A miniature active buzzer is connected at the collector of T1 for audio indication. The advantage of this tester is no false triggering due to the ambient light or electronic ballast operated tube lights. IC1 is a regulator IC used to give 5V regulated DC supply.

The 555IC Tester is used to test most widely used 555IC. The use of Timer IC555 proves its importance in almost most of the circuits. So it becomes necessary to build such a design to test this most popular IC. Although the IC555 is generally very reliable, there are occasions when malfunction does occur. The circuit shown here will provide a simple and effective method of testing suspect devices.

About the Circuit :The timer to be tested, IC1 is connected as an astable multivibrator. When the push to test button ‘S1’ is closed, capacitor C1 will start to charge up via resistors R1 and R2/P1. As soon as the voltage level on this capacitor reaches the trigger point of the timer, the internal flip-flop is activated and pin7 is taken low to discharge C1. The flip-flop is reset when the voltage on C1 reaches the threshold level of IC1. This takes pin7 high and the charge cycle starts once more.

The output of the timer pin3 is connected to a pair of light emitting diodes. When the output is high, LED D2 will be ON and D1 will be off. Conversely, when the output is low D1 will be ON and D2 will be OFF. The LED will flash ON and OFF alternately provided, of course, that the IC under test is a good one.

For readers who may have other application for the circuit and who wish to alter the frequency, the rate at which the LED flash is determined by the values of R1,
R2/P1 and C1. The frequency of oscillation can be calculated from the formulaf = 1.44/(R1+2(R2+P1))C1
If, as in this case, the value of R2 is much greater than the value of R1, the frequency can be approximated from the following                   f = 0.72/(R2+P1)C1

The Semiconductor Tester is used to test diodes, transistors and also to test the continuity. Many times it is required to test the semiconducting components. This is a simple and inexpensive tester, used to test virtually any kind of semiconducting components such as switching diodes, transistors, power transistors etc. It is also useful in finding functional, short circuited and internally open devices in semiconductor batches.

About the Circuit :

• The circuit is build around IC1 which consists of four NAND gates. One of the gate from an RC oscillator. The oscillator signal is buffered and made available in true and inverted form by the three remaining gates.
• The two color LEDs (Red and Green) indicates the direction of the current flow or the device under test. Resistor R1 functions as a current limiter.
• The signals at the input and the output of IC1 are applied to a pair of test probes, a two-terminal test socket for diodes, and a three-terminal transistor. The base current for the transistor on test (TUT) can be set with preset P1.
• Only one LED lights when component is functional. When the component is internally open, no LED lights. The semiconductor with internal short circuit is easily recognized by the glowing of both the LEDs with equal intensity.

The testing procedure for diodes, transistors and continuity testing is as follows :

• Transistor Testing : Transistor to be tested must be connected with the base, emitter and collector pins to the indicated socket terminal. If Red LED glows then transistor is PNP type. And if green LED glows then it is NPN type. If transistor is not functional no LEDs glows and if it is short both LEDs glows with equal intensity.
• Diode Testing : With this tester we can test the cathode and anode terminals of a Diode. As above place DUT in the indicated socket. If Red LED glows then the terminal, which is connected to TP1 is cathode and other is anode. If Green LED glows then the terminal connected to TP1 is anode and other is cathode. Testing of functionality and short circuiting is same as described in transistor testing.
• Continuity Testing : For testing the continuity, probes TP1 and TP2 are used. If there is open circuit no LED lights. And if both the LEDs lights with equal intensity then continuity is ok.