Home Brew Telegraph Sounder

This little project has taken some time.... initially, I was just "messing around" thinking about it, then I did some research into how to make an electromagnet, and saw some "ugly builds" of a basic telegraph.  So... I decided that I wanted to make something a little bit better.... Did some more "looking" and saw a design that was pleasing to the eye, and did not seem to be that difficult to make. However... the original was made in BRASS.. and I could not work brass to that tolerance. nor had I got the facilities/workshop tools etc. to carry out such precise workmanship.. Apart from that.. I am not very good with working with metal anyway... so I decided I would have a go at making it in WOOD !.

        The original design, was for having two electromagnets.. however, I decided that one would be sufficient for my purposes. as it was only for " amusement purposes only".. and "something to do".

   

 The first thing to do was draw out the design, and consider the materials needed to construct it, then go out and buy them..Nothing fancy.. a piece of wood... a couple of nuts and bolts and some very large size rubber tap washers for the electromagnet. and of course, some "magnet wire".

( I bought the bar, intending to use two magnets, but decided against it )
I bought two grades of magnet wire from Ebay suppliers... the first attempt was with very thin wire.. 0.1mm diameter,  which broke very easily, when trying to wind on... It worked, but I was not happy with it...

so I use the thicker wire. 0.5mm diameter

From the initial coil of wire, I decided I wanted about 100feet ( 33mtrs approx). from a 90 mtr roll.  Obviously, I could not measure that amount, as I was winding, so had to use the back garden to lay out the wire, and then rewind it on to a temporary spool, that I made from two plastic lids and a piece of tubing stuck together with impact glue ! ..I am not related to Heath Robinson, as far as I know ! !

To wind the wire onto the bolt, I used my trusty hand drill, lodged into my desk drawer, so that I could guide the wire with my left hand and slowly crank the handle to wind on the wire. I made a "support" for the coil of wire jammed into a lower drawer.

Pics show the attempt with the fine wire... but the principle was the same for the final 0.5mm wire. I had no idea how much wire would be wound on, so just kept going, eventually, wound on 5 layers.

which finished up looking like this...

Once the coil was wound, I tested it using a 9v battery, and it worked !.. so now it was time to draw out the shapes from the design, and cut them out..  I decided that the best way would be to cut out the paper shapes and then draw round them on to the piece of wood.

Using a coping saw, and various "formers" covered with sandpaper, the parts were made as follows.

Once all the surfaces had been smoothed down several coats of undercoat paint were sprayed on, and rubbed down between coats.

The designs I had seen on the internet, showed using an elastic band, or a spring for the "return" of the rocker arm, however, I did not like the idea of an elastic band, nor did I have any suitable spring available.... brain in gear... I decided that if I made the rocker arm heavy at the opposite end to the "tongue", then it "should" return on it`s own... so I laid out the parts to gauge where the pivot point would be on the rocker arm

and found a large diameter screw threaded bolt, that I thought could be used as an adjustable weight, screwed in or out to adjust....

 As the rocker is made of wood, I needed a small metal plate that the electromagnet could react to.

I also needed to have a metal tongue at the thin end for the adjuster screw to face up to. and found a small piece of brass in my "bit box".. which did the job ! . 

After completing the prep work, and doing the spray painting,. It was time to put all the parts together for a "test bed run", to make sure that it all was going to plan.

 The original idea of the heavy screw at the back end of the rocker, did not work very well, once the metal plate and the tongue had been added, so I looked in the "bit box" for a small piece of brass bar that I could drill and tap to add extra weight...

As you can see, the tap did not quite make it "square" into the drilled bolt hole, but, hey,.. I`m not an engineer, and it works O.K. for me ! ! 

The base was made up from another old piece, kicking around the workshop. You will notice it has had several "options" of other projects tried out on it... so I found a stiff piece of card from an old box, and cut to size, then glued that on, eventually, a couple of coats of undercoat, and some nice black gloss finished it off. 

Before all the paintwork was done, it was necessary to "locate" the parts, and drill holes, and underneath scour out some room to put the 9volt battery, and wiring. 

 Eventually, all the parts were removed, and a final coat of gold paint applied to the upper parts, before finally refitting them to the base, and wiring in the rats tail socket so that I could connect a key and prove that it worked !..  

here is a few "stills"  of it..... 

and finally, the video to prove it works......

 

 click on the little square at bottom of screen for full screen... turn up the volume, and enjoy !.