Electrostatic Polarity Detector




Introduction: Electrostatic Polarity Detector

Completed by Kristen Stevens, Karem Gonzalez, and Leslye Saavedra

An electrostatic polarity detector can be used to detect if an object is negatively or positively charged. We followed the steps from the following youtube video: https://www.youtube.com/watch?v=WptwVzK7cK0&t=255s.


FDS8958A chip- contains N & P channel enhancement mode power field effect

Plastic container

2 sizes of tubing


Jumper wires

2 LEDs

2 Switches

Solder and iron

Glue gun

1 K ohm resistors

Step 1: Preparing the Container

  1. Drill a hole in the lid the size of the smaller tubing.
  2. Insert smaller tubing through the hole and glue to lid. Slide larger tubing over it and glue. Seal the end of the tubing with glue.
  3. Cut 3 small sized pieces of the smaller tubing and 2 longer sizes. This will be the frame that holds everything in place. Glue them as seen above.
  4. Glue the two switches onto frame and snip inner two legs.

Step 2: Schematic

This is an image of the schematic we followed and a model of the circuit on a PVC board. Here we can better illustrate the connections we made. Pins 1-0 of the chip are connected to the switches. The switches allow the charges to be discharged; resetting the system. Pins 5-8 of the switch are connected to the 2 LEDs, which are connected to the 1 K ohm resistors. The resistors are then connected to ground and power and to the other side of the switches.

Step 3: Soldering

Use the schematic from the previous slide to attach the chip to the switches with a soldering iron and solder. If you have little experience soldering it would be easier to use an IC adapter and/or PVC board to solder on. Otherwise you can solder everything directly onto the frame following the schematic like we did.

Step 4: Final

Here is the final product. With 3 pieces of tape you can test out your device. Stack 3 pieces of tape onto each other onto a table and tab the ends. Pull off the first two pieces slowly and then rip them apart with force. Now one piece will be positively charged and the other negative. The LED that you have connected to power (red one) will detect negative charges and the other positive charges (blue one). If detecting a positive field the N-channel works because the P-channel will push out all positive charges and vice versa for a negative field. Thank you for reading our instructable and good luck with your project!

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    2 Discussions


    1 year ago

    What are the precautions that we have to take because we have been trying this one LED getting detected by simple touch to Tact switches also , and continues to glow.

    DIY Hacks and How Tos

    That is a really cool DIY tool. You should seriously enter this into the First Time Authors contest. I would vote for it.