Restoring a Telegraph Key / Sounder

20 years ago, I found this in my grandfather's basement.

I learned years later, that it belonged to my grand-grandfather.

I was immediately attracted to its complexity and beautiful engineering

As for cosmetics, it was not only oxidized everywhere, but the isolation on the cables was also history...

After some research, I found that this is a Field Sounder Mark II, c1900, and even late 1800s.
*Source: The Australian Telegraph Office - by Ron McMullen (link).

You can find the description at #586 here.

I took it apart and began working in bringing back some life to the wooden base. I then stopped the project and left it sitting in my basement for the best part of the last 20 years

The year 2020 came along and I felt it was time to finish what I had started and aim for a full restoration and shiny bronze, so here goes my step-by step process:

Step 1: Remove the enamel coat. I used gel paint stripper:

Step 2: Submerge the parts in Liquid Rust remover (which is a strong acid) and leave dor a few hours.

At least the rust was gone, but I was super scared after seeing the chemical reaction with the acid: It turned everything to a brown copper color. But not all was lost: it was time for Step 3.

Step 3: Recover the golden color: Rotary metal brush.

Now we're talking. The metal brush on your dremel is a quick and great way to both restore color and shine.

Step 4: Polish to remove scratches and provide a finished aspect.

Step 5: This is the final step: reassembly.

I also found the schematics for the operation with another key for both continuous and intermittent mode.

The metal plate reads: "Caution: C is not to be connected to Z without first disconnecting the battery."

Which makes perfect sense since doing so would short-circuit the battery.

Now to the elecronics.

I have no one to telegraph to however, I'm thinking of sneaking-in a battery and do some microcontroller magic so I can talk to it by tapping the key and obtain a solenoid response.

The solenoid is 12V, so the first thing I want to test is to have it potentially working with 5V, and it does not.

I may come with an external circuit powered with 12V.

To be continued...