TA-312 Field Phones

When I was helping my mom move, she asked if I wanted this box from my old room.

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I eyed the box greedily thought, "These will be perfect for fast communication when the zombies* come!" My significant other looked in the box and said, "Oh no, I don't want more junk that's just going to sit there." Then she looked at the phones more closely, smiled, and said just loud enough for me to hear, "Ohhh, for the zombies*."
I love her.
* In this instance, "zombies" is a metaphor for a generic SHTF/dangerous situation. A metaphor which does not exclude zombies. <_<

I don't remember where I got them from, but I remember messing with them for a bit, then losing interest. (I was obviously young and stupid) Now I was a kid with a new toy (all over again). I got my tools, pulled out the camera, and got down to business.

TA-312 Field Phone


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Battery powered portable phones that require only two wires to communicate with each other. The handset has a press-to-talk button on the side, and you can speak to listeners with it pressed, and vice versa. Unlike walkie-talkies, if both sides press their "talk" buttons, they can both speak and hear each other. (useful for long distance arguing!) Since the phones are completely dead (not using any power) while the handset is down, you can ring the other end of the line by cranking a small generator on the side. This will cause a small alarm clock type device to repeatedly hit a hollow part on the rear of the phone, and produce a *KLACK* *KLACK* *KLACK* sound. The volume of the ringing can be adjusted with a small dial.


As I reacquainted myself with the phones, I remembered these connection leads that are covered by a cap. (seen to the left of the wire leads)

The site indicates they are for connecting a touch-tone adapter for use as a POTS phone. I shorted some of the leads and managed to cause a clicking, but failed to produce any form of tone. Thinking about it now, the tone modulation probably takes place in the adapter. The leads probably only provide power and line connection.

As I cleaned them out and tested them, I found one that didn't transmit as loudly as the others. I opened it up and found it had spent some time at the beach.

(Note generator crank extended)
Rust and corrosion on most parts, and in the bottom of the container you can see some white; that's sand. It still works, a testament to how equipment can be made to last if people take the time.

Another phone lacked a KLACKer, and the generator crank didn't KLACK the phone on the other end. However, if you picked it up, you could talk on it fine. This unit also lacked all rubber weatherproofing. I opened it up and found nothing that appeared to be wrong. I began testing leads to make sure power was getting through, and one of the wires fell of the generator. There's your problem right there. I whip out the soldering iron and my amazing skills of shitty soldering, and manage to reattach the wire securely. As I continue my inspection, another wire falls off the generator. Another shitty soldering job later, things are looking better. The generator now rings the phone on the other end of the wire. I test the wires until I find the leads that went to the KLACKer, and try to figure out what to use to replace it. I try a small PC speaker and a clicker, which don't work, and I can't find the buzzer I used to have. I test it with a high-output LED, and it works well. Instead of just having the wires and the LED hanging out the hole made by the missing KLACKer, I rewire the leads to connect to the external power leads, and attach the LED there. (LED is the big clear/white thing below the top of the handset)

Not bad looking, and it's silent now. Just gotta figure out something to cover the KLACKer hole.

After a detail clean with a q-tip, here's a picture of the best-looking of the four.


Connecting the four in parallel turns them all into a party line. Since enough electricity is generated on the ring (generator crank), it would be simple to set up a central board and three remote phones with LED ring indicators. This way one person in the middle could watch for a blinking LED (a ring from a remote phone), and switch the local phone to converse with that remote user. With the central board, you could also make a party line switch so everyone could talk and hear at the same time. Also hadn't considered setting more wires than there are phones, and just having users carry the phones while roving. If something happens, they connect to the nearest set of wires, and relay their information to the central phone.

After creating the LED "ringer" I want to add a flip switch to choose between light and sound ringers. I'm still working out how the disconnecter works, but I think I'll wire the handset for a hands-free headset.

I only used a short wire for testing communication between two phones, but a receiving phone could hear but not speak if it lacked batteries, this is where I got the idea for an always-on headset that you could listen to, and pick up to talk back. However that might not be the case over longer distances. I suspect power will be required by the listener to amplify the degraded signal over a distance. Testing will follow.

I gotta get one of those touch-tone adapters, because at work we have a "Bat Phone" (which is just a red POTS phone) for testing land lines. It would be pretty awesome to have one of these as the Bat Phone.

Information is Power.
Fast communication is extremely valuable.