After looking through my top 20 ideas a theme of finance related actions such as spending, saving and using money emerged. The bank balance purse was the starting point for my project...
I went on the hunt for a coin counting machine but found that they we either too expensive or too big to fit inside a purse. Toy money banks seemed to be the best option and so i bought a Rocket Money Bank from the Science Museum range. The mechanism worked when a coin was put in, the value would be recognised, display it on the screen and set off the rocket triggering the sound and motor. I only needed the display and so disconnected the motor and speaker.
(Removed speaker and motor mechanism)
As a result of the motor and the speakers being removed, the unit required less power therefore 2 AA batteries were used instead of the original 4 AA batteries and the 2 unwanted wires were removed from the casing.
The money bank itself was fairly bulky so all of the plastic casing was stripped down and removed until just the circuit and screen was left.
To detect what coin is inserted there was a sliding strip that was set on a curve, so depending on the size of the coin the slider would move further along the curve.
Because the speaker or motor were no longer required, it meant new wires had to be soldered on to the circuit so that the display would change and go back to the start on a loop every time a new coin was inserted.
(Small yellow and red wires soldered on the bottom left of the circuit)
The circuit and screen were then attached inside an old purse, and the batteries were connected together long ways instead of side by side because of limited space.
Finally the the screen display and circuit were sewn inside the purse and the batteries connected.