This session we came up with a basic plan for developing a prototype.

Brought some components and gave them to Lachlan to build something before our next meeting.

Between this meeting and the next meeting Lachlan built a circuit and these were the notes taken:

Notes on First Prototype Build

Attempted by Lachlan

OP-Amps

The OP-Amp used for the first prototype is not a ‘precision’ OP-Amp. Probably means that the slew rate is slower and there is more noise. This may not affect the build but it is worth noting if an improvement to the quality of the signal is required.

The LM1458 has a required voltage supply of 22V. This is not suitable for our purpose. Moving to using the LM3412N as this is the only other OP-Amp available.

Polarised Components

All components on the signal side of the circuit need to be unpolarised. It is an AC signal being measured.

Practicalities

It would have been much easier if I had all the right gear. Was missing a breadboard with power rails, solder, an accurate way to read the data in real time (was going to use the Arduino but needed to download extra software which took time) and some components weren’t quite right (the caps were polarized, the OP-Amp was not ‘precision’, the pot was 10k not 1M and didn’t have a bipolar LED so used to LEDs in parallel facing opposite directions which may or may not have worked).

Function Generator

I downloaded ‘Audacity’ as this has a tone generator function in its dropdown menu ‘Generate – Tone’. Take care using this!! The audio plug is apparently quite sensitive so it is not hard to wire something up to it incorrectly and break the audio plug or sound card!