When my interest in building an accurate impression came about, I started a Facebook group (Ghostbusters TVG Prop Builders). I hoped for a while that the particular circuit board which they based the gizmos on would be identified. I finally found proof that they existed: an eBay auction. When I asked, the seller was tight-lipped. Fair enough. This seller wanted at least $300 for this item, so I passed.
Fast forward to recently- a member of the group said that his gizmo, unknown to him at the time, was an accurate TVG gizmo.
Drum roll, please....
It’s an Elka 160 calculator circuit board. It’s a Bulgarian calculator, so expect long wait times for this. I bought one, so I’ll post pictures once I receive it.
Also, the board covering the Lifegard logo on the...Lifegards...are just this circuit board shrunken down.