Roof-mounted changeable warning sign

[jtc078]

Can anyone provide me information about roof-mounted changeable warning signs. Who made them? How do they work? How long were they made?
I have pictures from the late 60s to late 70s of these signs mounted on MN State Patrol and PA State Police cars.
Here are the MN pics (From marooncruisers.com):

PSP Pics:


I believe this is the controller in a PSP car. I think it says Varicom, but I'm not sure.

 

[tsquale]

Have you tried the contact us form on Maroon Cruisers? Jay Sletten runs the site and has restored a few of the MSP cars. He is also still a current MSP employee. If he doesn't have the answer, I am sure he knows where to find it. If you can't get a hold of him, his brother Neil is on the forums here as @HCSO249 and he can likely get you in touch with him.

Both are very nice guys and willing to help collectors out.

 

[jtc078]

Have you tried the contact us form on Maroon Cruisers? Jay Sletten runs the site and has restored a few of the MSP cars. He is also still a current MSP employee. If he doesn't have the answer, I am sure he knows where to find it. If you can't get a hold of him, his brother Neil is on the forums here as @HCSO249 and he can likely get you in touch with him.

Both are very nice guys and willing to help collectors out.

Thank you! I'll give it a shot.

 

[coop359]

Wow. I just wanted to post this photo. My grandpa work for 3M way back in the 70s. He gave me this photo. Notice the lollipop lights are different but the license plate is 416 instead of 412. 3M was doing something with the Scotchlite reflec

 

[HCSO249]

Yep ask my brother Jay...if he doesnt know he certainly will try and find out. May take a bit of time as hes been traveling and working out of town (so to speak) but he is usually pretty quick to reply. coop359 You should scan that pic of the 71 Plymouth and send to Jay. He'd be happy to have it for his web pages. Sorry it took me so long to reply to this post

 

[esprole]

The Varicom Mobile Sign was a product of 3M. The only reference I could find was "Robert Fritts, Project Manager of the Graphic Technologies Group at 3M, designed the Varicom Mobile Sign patented in 1969"