Today we will be making a Circuit Tester. The main purpose of the circuit tester is to check if there is a good connection between wires or if a wire is good to use and that current is able to follow through. The schematic is very simple and does not require expensive equipment. The way works are you have two wires that are you contact pins that you'll be using to check the circuit. If we use a wire for our example, we can see that when we touch one with one wire and one end with the other wire, the buzzer will simply beep and the LED will turn on, indicating that there is a good connection and the wire is good to use in a circuit. This project will eliminate the need to guessing which wire to use and if you have made a circuit but it doesn't work this will check if there is a current flowing through or not.

Supplies

- 555 Timer

- Buzzer

- LED (Any colour)

- 330-ohm Resistor

- PCB Board and Breadboard

- Wires

- Soldering iron and Solder (Optional)

Step 1: Building the Circuit on a Breadboard

We have two ways we can make this. One way is we can make it on a breadboard and if you want to go to the next level I recommended purchasing a PCB and items that I have listed in my supplies list. If you choose to make it on the breadboard first and then you want to make it on PCB which is totally fine and it's beneficial so you know that there's no problem with the circuit itself. Let's begin!

Place the 555 timer on the breadboard
Connect pin 1 to ground and pin to power
Connect pin 4 to pin 8
Connect pin 6 to power
Take a wire from the output pin (pin 3) and connect it with positive ends of the LED and Buzzer
Take the negative end of the LED and connect a 330 ohms resistor and the other end of the resistor connect it to the negative rail
Connect the negative pin

We have successfully completed the wiring and now we can move on to testing it. Your circuit should look somewhat like the picture I have attached. Also, follow the circuit diagram for better understanding.

Step 2: Building the Circuit on a PCB (Optional)

If you like to build the circuit on a PCB, then this section will tell you how to build it properly and solder it properly. Before starting to solder on PCB, I would suggest getting a practice PCB and trying to perfect you soldering so it doesn't create problem when you're building the circuit. If a mistake is made during the process, it is extremely difficult take off solder. Have a solder pump so if you make small mistake you can suck up the solder so your circuit doesn't mess up. I have given a schematic that you can follow and it will hopefully help you while you solder.

Place the 555 timer on the PCB
Connect pin 1 to ground and pin to power
Connect pin 4 to pin 8
Connect pin 6 to power
Take a wire from the output pin (pin 3) and connect it with positive ends of the LED and Buzzer
Take the negative end of the LED and connect a 330 ohms resistor and the other end of the resistor connect it to the negative rail
Connect the negative pin
Connect a long wire to pin 2 and another long wire from ground. The ends of these two wires will be you contact points.

If you have completed this soldering, your soldering should like the picture I posted above.

Step 3: Testing the Circuit

As you can see I have created a testing demo that has one full wire and a wire that is cut in half. This shows that the circuit works correctly and it's a cool way of testing your circuit rather than using a normal wire.

Let me know if you have any questions and I will try to answer them as best as I could.

Link to video: https://drive.google.com/open?id=1aGt45hf6pM7Ru8gaS1RkLqLBoC6XrAcE

Thanks!