Power Logic Probe

Having a logic probe on your toolbox it's a very useful tool to analyze and troubleshoot the logic state of a electronic circuit.

You can easily find out the High state or Logic 1 , "Positive", and Low state or Logic 0, "Negative".

But it's possible to improve the potencial of this tool, it would be nice having light on this probe to illuminate the area of work that we are probing.

When troubleshooting we can make mistakes so it's nice to have a probe that is protect against short circuit.

And also having the opportunity to give positive and negative to the circuit at will to power devices.

On this project i show you how to make a Power Logic Probe .

Watch the Video

Watch the video and see how the Power Logic Probe works and how it can be a good asset to your toolbox.

Gather the Material

You will need for this project:

- Enclosures Box

- Circuit Board Perforated

- Electric Wire

- Battery Alligator Clips

- Power Connectors

- ThreePosition Switch

- Momentary Switch

- Flat Screwdriver

- Silicone Nozzle Cover

- 22 Ohms Resistor

- 68 Ohms Resistor

- 2x 10K Ohms Resistor

- 2x 1K Ohms Resistor

- 5V Zener

- 2x 1N4001 Diode

- Bc 557

- Bc 547

- 12V Relay

- 5mm Red Led

- 5mm Green Led

- 2x 5mm White Led

Get Started

To have a nice project in the end it's important to choose a nice enclosure to keep the circuit board, i chosen this one because its round on the edges so becomes comfortable to handel.

For the tip of the probe i use a old screwdriver that i didn't use, by changing the tip with a dremel to a needle tip, if you what you can use a tip from a multimeter leads.

Follow the circuit schematic and make the circuit on a perforated circuit board and keep in mind the components polarity.

With a drill make the holes for the switch, leds, and the probe tip.

I made also two cables one to connect the probe to the battery car and the other to the 12v cigarette lighter, because i designed this tool first to troubleshoot the electrical connections and devices in a car, so i have two cables to use, the alligator clips when i'm working on the engine and around the car and the cigarette lighter when i'm working inside the car.

I used a nozzle silicone cover to protect the tip when storage, also to increase the connection on the tip i painted with graphit 33 spray.

How It Works

To power the probe connect the leads to 12v power supply and push the power and reset button to turn on the probe.

Now you can probe the wires to check the polarity, the red led will be positive or logic 1 and the green led will be negative or logic 0.

Thanks to the white leds you will always have a light work illuminating the wires under test.

Besides probing you can also power devices for exemple in a car, lights, horn, radiator fan, relays, etc , with the power button position 1 will give 12v positive on the probe tip and position 2 will gibe 12v negative to the probe tip.

The probe have also a circuit breaker to protect the probe and electronic circuit under test, to power back on just push the ower reset button.

Final Thoughts

This is a nice and easy project to make and a very good tool to have for diagnostic the car wiring or a electronic circuit.