Something I remember fondly from my childhood in the 70’s was a set of toy phones that were wired together, powered by D-cell batteries, that actually worked. One was in each of my brother’s rooms and if either picked up their line, the other phone would ring and they could have awesome conversations about spy stuff. It was glorious wild fun to have our own working phones! I don’t actually remember using them that much, but having them there in case there was need for clandestine phone conversations was very exciting.
So, a couple years back I thought it would be cool for my kids to get to have this same experience. Sure, with all the iDevices in the world, a wired phone seems so passe, but I thought they might find the wired connection between their rooms a fun little diversion.
I started looking for a set like we had, and it was pretty difficult. What I found was vintage, spendy, and had no guarantees of working, so I looked into alternatives. What I finally discovered were military surplus Digital Non-Secure Voice Terminals (DNVT) Model TA-1042A. These things look indestructible, reminding me of scenes from the rebooted Battlestar Galactica.
These phones are designed to work either point-to-point with two phones like I was looking for, or through a matching telephone exchange connecting many terminals. There’s quite a bit of information about them online, including instructions of how to connect them. So, I picked up a pair. They then sat forgotten for a couple years. Recently rediscovering them, I asked fellow GeekDad Mike LeSauvage for some help with powering the devices. He gave me the specs I needed for an AC adapter. Get one putting out 20-56VDC with 100mA (0.1A), and I should be good. Digging around in a pile of my tech-waste I found a 25V, 4.5A adapter. Hacking up some old phone line and the old adapter from who-knows-what, I had the phones operational in minutes. The instructions for setting them up for point-to-point operations can be found on PRC68.com. The instructions refer to a the RCV and XMT posts both having a black and a red peg, but you can see that these phones were not set up that way. The following image shows the connection that worked for me. Be aware that if you are touching the leads when the phone rings, you will take quite a jolt! Use at your own risk.
The following video shows how the terminals operate. Lifting one receiver causes the other terminal to ring. Lifting the other receiver opens the connection. Each receiver has a push-button to talk. When the button is pushed the phones chime to signal an incoming message. In point-to-point operation none of the other buttons seem to do anything.
TA-1042A DNVTs are readily available on ebay, though it looks like at least $100 for a pair is what it will set you back. AC adapters that match the specs are available on Amazon mostly in the form of replacement laptop adapters, but if you’re the kind of person to buy these terminals, you’re likely to have an appropriate adapter lying around.
In writing this blog I discovered there was a reason these things reminded me of the rebooted Battlestar Galactica; because similar terminals were used in the show. You can see a non-working prop from the show selling for over $600 in an auction on Propworx.com. I guess $99 for a working pair isn’t so bad after all!
Now that my set is functional, I am going to give them to my kids, 10- and 12-years old, to use between their rooms. Or maybe, I’ll just place them around my house, as an off-network means of communication for when the Cylons attack.
Ryan Hiller lifts the receiver of his Digital Non-Secure Data Terminal causing the remote terminal to urgently chime. Anxiously lifting the remote-terminal receiver, young Hiller answers, “Yes, Sir?”
“This is Dad Actual… it’s dinner time.”
So say we all.