By WShawn
Supporting Member
Just for fun I thought I'd share this video showing my complete breadboard for the super-accurate PKE meter I've been working on since the early 90s (I work very slowly, partially due to feature creep).

I can't seem to get the YouTube code thing working (it's just producing big blank spaces), so you'll have to click on the links for the videos:

The circuit is driven by a Teensy 3.2 Arduino soldered to a Prop Shield LC that stores the two looping audio files. The code was written by Patrick B, AKA GohstTarp.

Activation and modes are controlled by three resistive touchswitches built from transistor pairs.

The LED chase can be run in one of two modes. In the default mode the speed of the LED chase is linked to the state of the wings. In the half state the lights chase at a slower speed. In the full state the lights chase faster. In the classic mode, activated by touching the third touch switch on the face of the prop, the LED chase speed is controlled by the pot in the handle, as it was in the original prop.

My 1989 PKE meter didn’t have a pot on the handle (you never saw it in the movie) so I tied the LED speed to the wings state, and I prefer that to having to dial the speed up or down with your index finger.

Patrick wrote code so the servos deploy the wings at the speed shown in Ghostbusters. I’ve seen some PKE replicas where the wings pop out WAY too fast. It takes almost exactly a second for the wings to fully deploy from their home position.

This video shows an earlier version of the circuit, before Patrick added the code to control the servo speed. In this case the servos move from home to half or full at the maximum speed the servos can move. This video also shows the option of deactivating the audio amp by touching the third touch switch for two seconds or more.

The circuit will be powered by five 2/3 “A” NiMH cells, replicating the battery configuration used in the original prop. The cells will be recharged through an external charger that will plug into the base of the handle.

In the first video the shell on the right is my modified Iona master. The shell with the touchswitches is one of the resin casts I made two years ago. I’ve posted pictures of some of these test pulls on other forums.

With the breadboarded circuit now working I set about the task of making printed circuit boards for the main circuit. I taught myself KiCAD to design the PCBs and had a batch of three fabricated by OSHPark.


The finished board will have PicoBlade connections for the wing LEDs, Display LEDs, Top Shell, Bottom Shell, Servos and Speaker. Unfortunately during my initial test of a board I mixed up the battery polarity going to that wire harness and fried that board along with a Teensy and Prop Shield. That was a $35 oopsie. I’ve order new components but haven’t had time to start new tests of the PCB.

In the meantime I’ve been working on a PCB for the green display LEDs. I might do a PCB for the wings, but I haven’t finalized how I ultimately want to fabricate those. I scratch built the ones shown in the video from styrene. I might revisit molding resin wings; my first attempts at resin wings in the early 2000s resulted in warped wings.

I need to make a few tweaks to my Iona master once I have all the hardware dialed in. I want to hold the shell halves together using machine screws and threaded standoffs securely glued into compartments in the upper half of the shell.

I’m hoping to get this all worked out by the fall, at which point I might offer kits if there’s interest.
ccv66, Christof liked this
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By doctorevil30564
that is impressive. Nothing wrong with taking your time and adjusting what you currently have as technology changes. I'm sure that once you have a finished version that folks here in the forum will be interested in getting either a kit from you or access to the pcb files and arduino code that you've made to make their own PKE meter based on your design. Now you have me wanting to pull the parts,etc. I had bought for a 3d Printed PKE meter back out to work on the electronics for it.
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