Continuity tester a handy tool for testing circuits

The Continuity tester Continuity is essential if current is to flow in a circuit. A continuity tester is useful for quickly testing open and short circuits and is one of the most used test tool when checking for wiring faults.

how this continuity tester works this continuity tester works by making a noise and the led lighting up to tell you that a electrical current is going through the circuit. If the tester is doing these actions it means that the circuit is functional.

How the continuity tester was made The circuit diagram was made in circuit wizard where all the components were put on the PCB on the screen to find the structure of the circuit. The tracks and pads of the circuit couldn't be too close and needed to connect correctly. Then the circuit was printed out and formed into a circuit board where holes were drilled into the circuit board to create the connection points for the real components. After that the circuit was put together and put in a box and labelled.

Time log 2016-05-07 testing the design by simulation and with breadboards 2016-06-14 printed circuit board layout 2016-06-23 construction of circuit 2016-06-23 testing circuit operation 2016-07-19 mounting and labelling 2016-07-21 reporting

Hazards when creating the circuit In the making of the circuit there are many hazards that could be bad for you and the people around you and they need to be corrected before going on e.g. : the drill bit for drilling the hole could be not on right and it miss drills (to fix this you could check the drill bit before drilling), the solder from the solder could melt on you or your cloths (to counter this you could where short cloths and solder carefully).

The circuits schematic diagram and components list COMPONETS LIST 10k Resistor (1/4W) 10nF Capacitor 220 Resistor (1/4W) 2-pin Terminal Block 470 Resistor (1/4W) 47k Resistor (1/4W) BC548B NPN Transistor Buzzer (Round) Red LED (0.2 in, 5 mm) 1uF Electrolytic Capacitor The circuits schematic diagram and components list

Changes that can be made to the circuit The flashing rate of the led and the pitch of the beep can be changed in two ways: 1. The 10nF capacitors can be changed: doing this will change the pitch of the beep. Increasing the value of the capacitor will make it deeper and decreasing the value makes it more high pitched and the led gets affected in the same way increasing the value makes it flash faster and decreasing the value makes it flash slower. 2. The 47k resistors can be changed: doing this will change the pitch of the beep. Increasing the value of the resistor will make it deeper and decreasing the value makes it more high pitched and the led gets affected in the same way increasing the value makes it flash faster and decreasing the value makes it flash slower. The flash rate of the led is hard to see. To get any significant change the value of the capacitors or resistors would need to increase massively.