Rich Decibels introduces himself by giving away a monstrous little laser-cut amp.


Hi, I’m Rich, the latest addition to the Ponoko blog team. And I’m going to be writing weekly articles about how digital fabrication is being used by electronics hobbyists.

I got started with DIY electronics about 5 years ago when I wanted a Smokey amplifier but couldn’t find a local stockist. The Smokey is a little battery-powered practice guitar amplifier that is built into a cigarette pack. It’s tiny and lo-fi but the distorted tone is actually quite awesome if you happen to play blues or rock ‘n’ roll.

I did a little research online and found that the Smokey amp was built around a common “LM386” chip. With only 5 components, the circuit is super simple to put together; the hard bit was coming up with a suitable enclosure.

Over the years I’ve come to find that this problem is common to many electronics projects: wiring the circuitry is easy but finding or building a good enclosure is expensive and time-consuming.

In this instance I settled on a Chelsea Golden Syrup tin. While this functions well and the kitschy aesthetic works, it was a lucky find – the inside diameter of the lid just happened to match the speaker I had on hand.

To introduce myself to the Ponoko community I thought I’d try to design a laser cut enclosure for a more repeatable solution.

Having no experience with laser cutting it took a bit of head-scratching to get my first design together; this instructable from (very cool open-source hardware company) oomlout was a huge help.

I used Google Sketchup to visualise the finished product in 3D and Inkscape to draw the cutting template.

The design is pretty straightforward, the only trick was accounting for the laser’s cutting width (kerf) in the tab-in-slot joints. I took a stab in the dark and made my tabs 10.2mm and slots 10.0mm. These joints proved sufficiently snug, though further testing showed I could go up as far as 10.5mm to get them really tight.

Three days after submitting my design files I had the thing in my hands. Considering it’s the first time I’ve fired up my Personal Factory I’m pretty pleased with the results – suddenly it feels like I’m living in the future!

Once I was happy with the mechanical design of the enclosure I enlisted illustrator/designer/superbabe Kelly Spencer to add some pretty to the box for round two.

Here’s a really quick demo to show you what it sounds like.

The product plans for the first version are available for free in the Rich Decibels Personal Factory showroom and complete build instructions for the circuit are up on my website so you can go and make your own.

Once Kelly and I have tweaked a couple of technical details on the second version it will be up for sale in the showroom too.

Giveaway: because I’m new here and I’m desperate for everyone to like me I’m giving away one of these amps! This happy loud-face yelling amp guy needs a name – leave a comment with your suggestion and I’ll choose a winner a week from today. One entry per person please.

Update: thanks everyone, the competition is now closed. Congratulations to Sebastian, he scraped in at the last minute! I’d like to welcome Howlin’ Gaptooth to the world!

Posted in Contests + Competitions, Electronics + Robotics, Laser Cutting, Maker Stories, Rich Decibels by Rich Decibels | Comments are off for this post

Make your own stuff using: Laser Cutting

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