Raspberry Pi Projects by Andrew Robinson

Author:Andrew Robinson
Language: eng
Format: epub, pdf
Publisher: Wiley
Published: 2013-12-26T16:00:00+00:00

Wiring

You will connect the relay in parallel with the switch. This allows the relay to override the switch to turn the toy on.

Open the case by removing the four screws as shown in Figure 10.2, taking care not to lose any bits or move parts too far out of alignment.

An important skill of hacking is remembering how you take something apart so you can put it all back together. You could try filming it with a camera phone or similar, so you can play it back to see which part goes where.

Series and Parallel Circuits

Series and parallel are two names to classify how components in a circuit are connected. In series, as the name suggests, the electric current flows through all the components in a series, one after another. As such, if you have switches wired in series, then all of them have to be closed for the current to flow. Breaking one of them will break the circuit.

In parallel, the flow of electricity splits and so closing any switch wired in parallel will allow the current to flow. This is because electricity tends to take the path of least resistance, which in parallel circuits will be through any closed switch. For the toy, the closed PiFace Digital relay contacts will bypass the toy's open switch.

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