Heavily modified GEC (not GPO) 746, that isn't actually a phone as such...

[Key2871]

Isn't that so frustrating when you know you have something but you can't find it..

Well you have a heart start with moving forward.
Good luck.

[twocvbloke]

Well I finally found my crimping tool (had been "relocated" by little Miss Adventure, aka Peggy, on one of her meanders round my room knocking things over!!), so after slipping the phone's cable grommet onto the cable, I attached all the terminals needed onto the wires and mapped out where they go to on the DB25m plug, just need to work out how I want things to connect there that make some form of sense, but I'm procrastinating on that part as I started playing with the little amplifier circuit board...

Rather amusing little thing, though due to an intermittent contact in one of the crimped terminals, I was briefly blasted with mic feedback into my right ear, acoustic shock is something to behold, ear's still a bit warm & head's still a little spinny even now half an hour later!!! That and trying the same setup with a carbon granule Tx resulted in my being able to listen to BBC Radio 2 (Steve Wright from the sound of it, didn't know he was still going!) with the amp turned all the way up... 

But with a 4T receiver as the transmitter, it seems to work well, a bit harsh, but it is currently only experimental...

[RB]

Congrats on your progress!
And your resolve.
I like the reference,"little miss adventure".
We have a 1 year old grand daughter with the same characteristics.
Every morning, she makes her rounds around the rooms she is allowed to go into.
We host a daycare for all four grands. "wife is retired grade school with early childhood training".
So, every room is a class room.

[twocvbloke]

Yeah, Peg's a character for sure, and the name's a play on words as it always turns into "misadventure" for her, particularly when she walks onto something and falls off spectacularly... 

[twocvbloke]

Tidying up the mess I made, still not wired up internally, I just shoved the cable in and mounted the grommet to the base, but even so, with the new cable, it looks so much neater, I can understand the whole "use what you've got" as it seems to have originally been built with the two separate cables, but, neatness just looks nicer, it's possible they used separate wiring for audio and power/buttons to shield one from the other to isolate the audio side from any noise from the power line, but that's just a guess, still got to play with wiring to see how well it performs... 

[FABphones]

...I was briefly blasted with mic feedback into my right ear, acoustic shock is something to behold, ear's still a bit warm & head's still a little spinny even now half an hour later...

I couldn't help but be reminded of this scene from tv comedy 'Father Ted'.
Go to 9:08 in the clip:
https://www.youtube.com/watch?v=tmq_iFgbpEo

[twocvbloke]

I couldn't help but be reminded of this scene from tv comedy 'Father Ted'.
Go to 9:08 in the clip:
https://www.youtube.com/watch?v=tmq_iFgbpEo

Yeah, it wasn't far off that... 

[Key2871]

Hey that's nice! One cable is definitely better. Nice work.

[19and41]

I couldn't help but be reminded of this scene from tv comedy 'Father Ted'.
Go to 9:08 in the clip:
https://www.youtube.com/watch?v=tmq_iFgbpEo
[/quote

Here's the one it brought to mind for me.  It is just the phone bit.

https://www.youtube.com/watch?v=r2OzORTen_k

[twocvbloke]

Thankfully I was powering the amp circuitry from USB power, so no crossed wires with mains electrickery were encountered... 

[Key2871]

True, but acoustic shock is not pleasant..

[twocvbloke]

It certainly isn't, the worst instance I've had was when trying to get one of the uncle's mini-hifi systems to work (it was damaged by water ingress, but I didn't know at the time), I was stood in front of it pushing buttons and twiddling wires trying to get audio from it, speakers either side of the unit so I had full stereo "sound", and all of a sudden it made the loudest roar of white noise I'd ever heard, and it was like I'd just been stunned with a phaser, I just fell to the floor and pretty much knelt there for a few minutes stunned and unresponsive, took a while to regain my senses and declare that system dead, then head back home (thankfully here next door!) to recover... 

On the plus side though, the speakers survived and I now have them, there are apparently some things Sony makes that are pretty bulletproof...

[twocvbloke]

Latest pre-fab off-the-shelf parts have arrived, a pair of timer-relay PCBs, my thoughts are to use them for two purposes;

One, the buzzer/ringer in the phone thing, so when a "Call" button is briefly pressed on an outside panel, it'll buzz the phone for a set amount of seconds, and;

Two, for operating an electronic/magnetic door lock (or simulation of) from pressing the big red button so the door is unlocked, again operating for a set amount of seconds and allow the door to be opened, then switch back over to locked, also operating the "Unlocked" lamp on the phone...

Of course, being a cheap ebay-acquired item, there's no included instructions, or model numbers, or anything to suggest how they work, thank goodness for google searches though as they're "FC-31" 12v delay relay timers, or copies thereof, and for archiving sake I'm adding a schematic of them here too, with some slight alterations to make it more understandable, well for me at least... 

[RB]

They look like pretty standard 555 timer boards.
with 2 groups...
1-quite rapid release after trip. and
2- extended time passes before release after trip.
adjustable within each set of limits.
should perform well for your needs!
They also come in "interval" models,
Which would allow a lite to "Blink" while active.
Pretty versatile things

[twocvbloke]

The IC on the board is apparently a CD4541BM (see link), a CMOS Programmable Timer, seemingly a Texas Instruments chip too (though originating from china, it could be a copy or clone, or even a reject that "works well enough"), I did look at NE555-based timers but I liked the look of these ones I got, and after figuring them out, they work well...

https://www.ti.com/store/ti/en/p/product/?p=CD4541BM

And speaking of working, I did a temporary lash-up of one connected to a buzzer and had to take a video clip of it, may wish to turn the volume down as it's a loud little buzzer!!! 

https://www.youtube.com/watch?v=tnoxjFonAJc