A cable tester circuit is a tool used to confirm that a cable is functioning, usually by looking for shorts (wires that are connected incorrectly) and continuity (open wires).
A cable tester circuit is particularly helpful when working with multi-core wires, which are cables that have numerous insulated conductors bundled together.
This guarantees that every single wire in the cable is whole and has not broken at any point along its length.
For this, a simple multimeter may be used to measure the continuity between the matching ends of each conductor in the cable.
Circuit Working:
Parts List:
| Category | Item | Quantity | Power Rating |
|---|---|---|---|
| Resistors | 2.2k | 2 | 1/4 watt |
| 10k | 1 | 1/4 watt | |
| 1k | 4 | 1/4 watt | |
| Capacitors | Ceramic 10nF | 1 | – |
| Electrolytic 10μF 25V | 1 | – | |
| Semiconductors | IC 555 | 1 | – |
| IC 4017 | 1 | – | |
| LEDs red 5mm 20mA | 4 | – | |
| Miscellaneous | 4 cable wire bundle | 1 | – |
| Power Source | 9V Battery | 1 | – |
The multi-wire cable tester, which we are demonstrating in this circuit, allows us to determine whether a wire or cable is faulty.
A unique semiconductor known as a IC1 555 generates a consistent electric pulse akin to a clock.
There are three circuit components that may be adjusted to control the pulses speed.
To determine the components to utilize to attain the appropriate blinking speed for the LEDs, you may use an online calculator.
The IC2 4017 decade counter is a semiconductor that accepts the pulses from the IC1 555.
This chip functions similarly to a unique counter with a four digit maximum count.
It has four outputs, each of which is linked to a separate cable tester LED.
The counter monitors the pulses it receives and repeats the process of turning on each of its outputs one at a time.
Thus, each LED turns on in accordance with the counters sequence.
We have cleverly linked the reset pin of the IC2 4017 counter to its fifth output, which is not intended for LEDs. This serves as the counters finish line.
The fifth output also turns on when the counter reaches its fourth output, which turns on the fourth LED.
This fifth output activation sets off the reset, which resets the counter to its initial value and illuminates the first LED.
The counter generates a continuous loop by resetting itself sequentially reading each LED output.
If the relevant wire in the cable is in excellent condition, every LED has an opportunity to light up with this continuous loop from the counter.
An LED that is damaged will not come on during its turn in the sequence since there is no way for energy to reach it.
You can quickly ascertain whether all of the cables are in good working order by looking at the way the LEDs blink.
All four LEDs should flash consistently to indicate a healthy cable, if any blinks are missing the matching wire has broken.
Formula:
The circuit uses 555 IC to produce a clock signal, and the values of the resistor and capacitor determine how frequently this signal occurs.
The applicable formula for determining the frequency is as follows:
Frequency (f) = 1 / (0.693 * (R1 + 2 * R2) * C1)
where:
- f = Frequency of the clock signal in hertz, Hz
- R1 = Resistance of resistor 1 in ohms, Ω
- R2 = Resistance of resistor 2 in ohms, Ω
- C1 = Capacitance of capacitor 1 in farads, F
You may find the frequency at which the blinking LEDs in the cable tester will blink by using an online 555 IC frequency calculator or by entering the resistor and capacitor values into this calculation.
How to Build:
To build a Multi-Core Wire using Cable Tester Circuit following are the steps for connections:
- Gather all the components as shown in the circuit diagram above.
- Connect pin 1 of IC1 555 to ground.
- Connect pin 2 to pin 6 of IC1 555 through capacitor C1.
- Connect pin 3 of of IC1 555 to pin 14 of IC2 4017 through a resistor R3.
- Connect pin 4 and pin 8 of of IC1 555 to positive supply of 9V battery.
- Connect pin 5 of of IC1 555 to ground through capacitor C2.
- Connect pin 6 of of IC1 555 a resistor R2 between pin 6 and 7 of IC1 555
- Connect pin 7 of IC1 555 a resistor R1 to positive supply.
- Connect pin 2, pin 3, pin 4, and pin 7 of IC2 4017 to one end of 4 cable wire bundle through resistors R4, R5, R6 and R7 and other end of 4 cable wire are connected to 4 red LEDs respectively.
- Connect pin 8 and pin 13 of of IC2 4017 to ground.
- Connect pin 10 of IC2 4017 to pin 15 to IC2 4017.
Safety Measure:
- To reduce the risk of shock, only use the cable tester at low voltages usually less than 24V.
- For safer use, if you are not experienced working with electronics, think about using a pre built cable tester.
- Recall that using these precautions can help avoid accidents and guarantee a trouble free cable testing procedure.
Conclusion:
Four conductor cable broken wire testing is made easy with this easy to make DIY cable tester circuit that has blinking LEDs.
Build it yourself and find the problems fast for effective fixes!