The PKE meter, whist being one of the most instantly recognizable Ghostbusters props is unfortunately one of the more difficult to build. The PKE meter was built from a heavily modified, vintage Iona shoe polisher. These are getting harder to find though sometimes crop up on ebay.
The innards were all stripped out and the body extensively modified.
The electronics set up inside was completely custom, incorporating servos to push the PKE arms/wings out. a roller was added where the motor vent on the body to control the speed of the lights.
The original PKE electronics. As you can see, extremely complicated and very tight on space
There are very few people who have offered PKE electronics kits and making your own would require extensive electronics knowledge. www.hyperdynelabs.com offer PKE circuits but they are expensive.