Whether you're just starting out on your electronics adventures and just need to verify a five band resistor code, or like myself, you've accumulated a whole bunch of components over the years and not quite sure what they are or whether they're still functioning, this component tester will help you out. It's extremely flexible and although it just says transistor tester it can do so much more.
In this Instructable I show how to build the tester from a kit. I show the complete build process and point out any potential problems. The video shows the build and the following steps explain the process.
The kit is available on this link:
There are no instructions with the kit but the circuit board is very clearly labeled with the component values. Just be careful to choose the correct components and place them as shown.
Step 1: Solder the Resistors
When building these kits it's a good idea to start with the lowest profile components first and that will be the resistors. The resistor values are in the five band colour code and that's not always straightforward to decipher. Check each value with a multimeter to be sure.
After soldering take care when cutting the component leads flush with the board. Do not let the leads just fly around everywhere because they will surely find their way somewhere where they're definitely not wanted!
Step 2: Solder the Capacitors
The capacitors are for the most part clearly marked. There is one 1 nanofarad capacitor marked as a 1 n J, this is clearly marked on the on the board. There are two electrolytic capacitors which are polarized so pay attention when fitting them. The negative side is marked on the capacitor and on the circuit board the negative side is indicated by the lines. The positive lead on the capacitor is longer. There is an extra capacitor included but this is not part of the build this is for calibrating the tester. It is circled in yellow in the photo.
When fitting the two small 22 Picofarad capacitors don't push them or force them down onto the board too far. If you try and force them all the way down to the circuit board they're going to crack.
Step 3: Solder the Transistors
Next fit the transistors. I put one of the brass spacers for the LCD on the board as a reference point for the height. You do not want the transistors protruding up too far and touching the LCD. Make sure to check the transistor part numbers against the PCB marking.
Step 4: Solder the Remaining Components
Now fit the remaining components. The clip for the battery, switch, socket for the processor, the crystal, socket for the LCD and the zero insertion force “ZIF” socket. Two of these were supplied with my kit for some reason, choose your favorite colour!
The connector at the top for the LCD is marked as 5 through 12. That matches up with the header that you solder on to the LCD which starts at pin 5. Take a little bit of care with the crystal, the legs pass through glass insulators so do not over stress the legs. The socket for the processor has an indication for pin 1 a little dent in in the top. That indicates that the top corner is pin 1. Finally the LED is marked again on the circuit board. It has a flat on one side to indicate the negative lead and similarly to the capacitors the positive leg of the LED is longer.
Step 5: Check the Voltage
Before fitting the processor, connect a battery up and check the power connections on the chip. To do that we count down to pin 7 which should be positive and pin 22 should be negative and they're opposite each other in the IC socket. You should see +5 volts on pin 7 when you press the switch down. We can put the processor in now, as supplied the legs are probably going to be a little bit too splayed out to fit in the socket. Gently, on an anti-static surface, bend the pins over so that they're pointing straight down.
On the processor, pin one is indicated by the indentation on one end. Check that all the pins have gone home into their sockets.
Fit the LCD panel and battery to test that it's working.
Step 6: Calibration
To calibrate the unit we need to make up a linking wire to join the 1 2 & 3 terminals. On the ZIF socket, the first 3 positions are “1” the middle position is “2” next to the line that you can see in the in ZIF socket and then the final three are “3”. With the link in place follow the prompts until it says “isolate probes” then remove the link. It will then prompt you to put the calibration capacitor in and the test will complete.
Step 7: Fitting the Case
The next challenge will be fitting the module into the case. When attempting to fit the module into the case we encounter a problem. When we offer the parts up because of the height of the LCD panel the ZIF socket is recessed and you can't get the nut onto the switch. My solution is to enlarge the cutout for the screen so that it passes through.
I've also opened up the rest of the slot for the ZIF socket latch. This enables the latch to close fully.
My thanks go to Banggood for supplying this kit for review and I hope you have as much fun building it as I did.
Step 8: Testing Time!
With the unit complete we can now sort through our pile of components to identify them and check that they're operational.