Some time ago, Idecided to make a continuity and polarity tester. I searched instructables but nothing showed up, primarly becouse one needs a battery and the other can't have one. So I thought about it and I found a way to have both in the same device. but, I then thought about it for a little and decided that a transistor tester would also be very simple to add, so as an LED tester.
After looking a lot for a case that would be small enough to fit inside a pocket, but big enough to hold all the electronics.
So, this tester has the following functions:
Step 1: Materials
To this project you will only need simple materials that you should have laying around (in my case they all came from an old printer except the case, the SPST switch and the battery pack, however the last two came from a kid's toy).
3 LEDs the color you want (mine were 2 yellow and 1 green);
Battery pack (at least 3V to the LEDs)
A 1000 ohm resistor,
1 SPST switch,
1 2 pin connector,
1 3 pin connector,
A neat case (mine was a sewing button case)
To me, since I had all the materials laying around I only purchased the case, that was 0.90ˆ, so it costed me 0.90ˆ and I got 6 sewing buttons (no idea what I can make with them... yet)
Step 2: The battery pack
My battery pack didn't fit inside the case, so, I needed to make it fit, removing the lid and cutting it to size.
Step 3: Electronics
For the electronics just follow the schematic.
Step 4: Make it look neat
Now just stuff the electronics in the box make it look good and label it.
Step 5: Done and how to use
You now have a homemade 5 in 1 electronics tester
How to use:
Continuity - set the switch to C and touch the probes into what you want to know if has continuity.
Polarity - set the switch to P an touch the probes into the poles. The X LED will light up if the polarities are wrong (the red probe is plugged to the - pole and vice versa) and the "right" LED will light up if the polarities are correct (red to + and vice versa)
LED - touch the LED's leads to the side of the 2 pin connector or plug them into the pin holes and watch if it lights up or not. If it does, the LED works and you foud it's polarity. If not switch places. If it lights up you have your polarity, if not, it's blown.
Transistor - use the connector the same way as the LEDs, but the indicator is the OK LED. The indicator is the round part. If it is facing forward, it is one type, if is the other way, it's the other type.
Diode - use the same way as Continuity or in the transistor tester