...It all started a few months ago when I mentioned to someone I wondered if I could make a radio inside a standard Tic Tac container using no SMD components complete with speaker and battery.
Not a chance was the reply... So, not to be deterred I see a challenge that had to be cracked....
So I decided on a TDA7000 based FM one with an LM386 audio amplifier. As you can see getting all these bits into a standard Tic Tac box might be a bit of a problem... especially as there was Tic Tac's still in it
.. so after munching the Tic Tac's, I cut the matrix board to fit inside the box and started added components - designing the layout as I went, and the result was this....
The tuner circuit was virtually as the datasheet except in this one I used a variable capacitance diode (varicap) and a preset potentiometer for the tuning (the other preset is for volume but you can't turn it up too much (see later).
It could quite easily be transferred to a PCB using this layout. I had no idea however if it actually would work at this stage.
Luckily I have a lot of spares parts salvaged from old equipment and I found in there an old laptop speaker that was almost the
same size as the box. Maplin sell a battery holder for N cells which turned out quite handy as it also fits the A23
12V battery that I was going to use... But the real question was - was it all going to fit in?
...Just!!! - with a small switch added (see above) to turn it on and off and the speaker lying on top of the battery. I had to make a slit in the plastic otherwise I would not have got the switch into its hole! A strip of clear tape then holds the speaker on top...
....so applying power - I got.... pagers...!!... actually this was good as it meant it was working but not quite where I wanted it -
I needed more turns on the coil. After a few attempts, its working nicely now on 88-108MHz. It does go a bit unstable if turned up too much
and the battery life is awful, but I proved it could be done and was quite pleased how it turned out in the end...
I wonder what else I can make in a Tic Tac container Especially as you can get the much larger cased Tic Tac 100's :-) Watch this space!