Introduction: Three Tool Electronics Kit.

About: Bytesize articles instead of a trilogy in one post.

This kit is three simple electronic tools. A continuity, polarity, and logic tester. Somehting you think you will never use till you need them. Herethee are in one pocket size box.

A soldering iron can be a tech's best friend. You never know when you need to repair an electrical connection. You can actually do a whole lot more, You can rescue parts for reuse. You can build your own simple test equipment. You can even build your own projects. You do not have to get a fancy soldering iron at first, but later as you gain experience, You may certainly want one. You also will want to learn about electronic symbols so that you can understand at least simple schematics.

Step 1: Continuity Tester.

Per Wikipedia:

A continuity tester is an item of electrical test equipment used to determine if an electrical path can be established between two points;[that is if an electrical circuit can be made. The circuit under test is completely de-energized prior to connecting the apparatus.

One of the first pieces of test  equipment I ever made was a continuity tester. What is that? it is a tool to see whether a wire cam make a complete circuit.  There are no breaks in the wire. Most of what I do is low voltage, so parts are not that critical. To make the continuity tester, I rescued a battery holder (from the motherboard) and an led from a dead computer. Saved a few bucks right there. So a soldering iron can get you free parts! The continuity tester is just a battery connected to a light bulb or the like.

Step 2: Ttl Polarity Tester.

Per Wikipedia:

A polarity test is used to find out the electrical polarity (positive or negative) of the voltage.

The second project was to make a polarity tester. I wanted to know which side was positive and which was negative. Two leds (resitors if needed) and test leads from a dead volt/ohm meter was all that was needed here. If the red lead was connected to the plus or positive side of a connection (black lead should be connected to ground) the the top led would light. If the wiring were reversed  then the other led would light. Great for testing diodes to see which way the should be conneccted to a circuit. You can als test low voltage batteries to see which is the plus (+) and negative (-) sides.

Step 3: Ttl Logic Tester.

Per wikipedia:

A logic probe is a hand-held pen-like test probe used for analyzing and troubleshooting the logical states (Boolean 0 (0 olts) or 1 (5 volts)) of a digital circuit.

So far that is pretty simple stuff. Logic testers at one time were very expensive. Now you can get them pretty cheap at your local electronic store. Logic tester is sort of a simplified voltmeter that can only test for five and zero volts. With digital electronics that is all you need to test. For example, you may want to see if a parallel port is sending a signal on a particular wire. Maybe there is a break in one wire of the cable. You can test each line or wire individually for the result. We like to interface or connect electronic projects to the parallel port. You could also use this for the Arduino, Raspberry Pi. or any device that has a standard digital output. For example, I have and led connected to one of the digital ouput lines of the parallel port. For some reason if the led connected to the parallel port data line is not lighting up when it is supposed to. The logic tester can determine if the wire is outputing the 5 volts to light the led. If not it may be a software or programming problem. You then have to adjust the software. If you are getting the 5 volts, then the led may be faulty. 
As I said earlier, logic testers even simple ones were not inexpensive. Found a magazine article that had a circuit to build your own. That meant for a few dollars for a few parts, you could have a logic tester instead of paying many dollars for one from and electronics store. I have since bought logic tester, but I still end up using the one i soldered together from the magazine article. Now you can find a zillion electronic circuits for the web that you can build (aka solder together). More info on the parallel port digital outputs at:
Parts needed:

1 - 74ls367 IC (integrated circuit)
1 - 16 pic Socket for the IC.
1 - Breadboard in breadboard format. (i.e. Radio Shack Model: 276-159  or Model: 276-150)
2 - Led's s/b different colors. (i used the same color leds but wrote on the board which was which.)
2 - 1 k resistors (1000 ohms)
3 - Alligaor clips
Wire for connections and connectors.

Solder the socket in first.
Solder wire.
solder resistors.
Solder in diodes carfully noting which way they should be attached.

Note: if you use a breadboard socket such as RS Model: 276-003 then no soldering is required.Plug and play.

Playing with the parallel port. if the data line (2-9) is trn on the "hi: led will turn on. If it is not then the :low led will turn on. You can only test one line at a time.

Note: it can be used with microcontrollers also, not justt he pc parallel port.

Step 4: All in One Case.

Anyway, even with these three (fairly) simple projects, you can have some pretty neat testing tools on the cheap. You will volunteer to take old and or dead  electronics from friends or whomever. As you can rescue all kinds of parts for free and save yourself lots of money. The soldering iron will pay for itself in no time at all. Or as they say, the more you know.....

Put everything in a small box that can fit in your pocket and you have your testing tools with you at your beckoning.

Note: battery should be kept in a small plastic bag s it does not get shortedout in the box.

Step 5: Planned Logic Probe.

Found this circuit on the net. It uses a cd4001 instead of the 74ls367 which should be easier to find. The probe also includes pulse like most testers. Will let you know how it turns out.

Step 6: Signal Generators.

Collected circuits I plan to mod and build.

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