I had a really useful mentoring session with Mitch Altman, Majenta Strongheart and two other Hackaday Prize entrants on Thursday. It was really interesting to see how the other entrants approached their projects, and I learnt a lot from talking to Mitch about the development process.

Coincidentally, Mitch has previously built an Arduino-based synth with a lot of similarities to my project. I looked at his schematics before the session and noticed a few things:

• Both our projects used an Atmega328 to generate audio
• Both projects used an LM386 to amplify the audio
• While my project uses a relatively expensive chip to boost the voltage of 2 AAA batteries, Mitch's synth runs directly from 3 AA batteries

This comparison was really interesting and useful - it told me that my approach to the circuit was fairly uncontroversial, but it also suggested that I could do away with the most problematic element of my design, the expensive and noise-producing voltage boost chip. I hadn't previously realised that the Atmega328 could run happily on less than 5V (forum posts had suggested otherwise), so it was very gratifying to hear Mitch confirm that it works fine on 4.5V. Straight after the mentoring session, I hooked my breadboard circuit up to three AAA batteries and was excited to realise that it worked fine, with barely any noise.

A few other things I took away from the mentoring session:

• My problems with making mistakes during PCB design are normal, and it's an accepted part of the development process to just hack the incorrect design and then incorporate the fix into the next version
• It might be worth investigating Seeed Studio in future for board assembly (in case me hand-soldering the boards becomes a bottleneck when producing larger quantities)
• CNC routing could be an option for the case if laser-cutting isn't suitable

Overall, really happy that I was able to take part in this mentoring group - it helped me with both big-picture thinking and with the specifics of my project.