Things With Strings

I'm planning on building a bass drum module, and I will need a pulse generator to test it, so I knocked up a circuit based on a 555 timer in ASTABLE mode and put it in an Altoids™ tin. You can easily find a circuit for this just googling around. I drew one up in Kicad like this. As I wanted this to be a pulse generator for triggering a drum circuit, I wanted the frequency range to fall within a range that would be useful for music, which is calculated by a combination of R1, P1 and C1 in the circuit diagram above. There are plenty of on-line calculators that will help here. I used this one  http://www.ohmslawcalculator.com/555-astable-calculator  (P1=R2 in the calculation). I found that a combination of R1=3K3, P2=1M and C1 as 2µ2 gave the best range for my purposes (approximately 0.327Hz to 198.761Hz). I had a small piece of perfboard offcut that I tried to squeeze it onto, and here is the layout. For the output jack, I used a 3.5mm jack I salvaged from an old P...

After the success of Pete's Bazz Fuss  I figured it was my own turn. I've only ever used stripboard in the past, but wanted to have a go at building a circuit on perfboard instead, so wanted to choose something relatively simple for a first go. The circuit I chose was the EHX™Muff Fuzz™ which despite it's name os more of an overdrive than a fuzz type effect. I drew up my own perfboard layout as below, taking care to make sure the components could be connected easily when soldering. Soldering up was relatively painless, and I was quite please with the neatness. You can see from the pic below that it is a mirror image of the layout above. I used 2N5088's for the transistors and 1N60P for the diodes. The picture below shows the component side of the board prior to shortening the transistor legs.  It worked pretty much straight away to my relief, and sounded OK, so I boxed it up in a 1590A sized box (always a painful process) and here is the f...

It's been ages since I built an effects pedal, so to get my soldering chops back up to speed, I decided I'd build a simple fuzz pedal for my long-time friend Pete as a surprise present for his impending birthday. The circuit I chose was the Bazz Fuss (yes that's the correct name)  which you can read about here if you care to. I went for the basic v1.0 of the circuit and used a 2N3904 for the transistor, and boxed everything in a 1590A sized enclosure. Despite a number of stupid mistakes that I had to rectify, I got it all done and boxed within a day, complete with lo-fi graphics. Here's a gut-shot. gut-shot And here is the finished item. lo-fi graphic It sounded OK when I played it although it needed the volume knob maxxed out to get the best out of it. Maybe a higher gain transistor would have been better still. I'm pretty sure Pete will like it though.

I saw a piece of scrap offset in my bin that got me wondering about whether to try cutting some thin slices of wood and laminating curved sections. I tried to bend the piece of scrap around an 11" diameter MDF circle I'd made previously and I was quite surprised just how flexible the piece of scrap was. The scrap was varying in thickness, but one outer edge was about 0.15 inches. The photos show how easily it bent, and this was just dry, no steam or water involved. I might try laminating a few layers out of curiosity. scrap and 11"MDF disk test bend

After having all three layers done, I decided to try to get the middle layer (shallowest) to size using a router and template, then I would glue all three layers together and machine the outer two layers using the middle layer as a router follower bit against the middle layer. In short this turned out badly, as I broke the middle layer whilst trying to route the inside surface. Fortunately I was able to patch it up, and in the end the patch should be invisible, but I decided at that point that it was probably best to get the three layers glued together before I made an unrecoverable mess of things. glued and clamped I'm not 100% sure how I will shape it yet. Probably router plus jig for the outside and sanding drum for the inside. Part 2 is here

I'm still experimenting with things really, and decided to try a different approach for the next segment layer. This time I thought I'd make a octagon using 45 degree scarf joints. There are a number of reasons why. I'd had difficulty with the mitred angles on the previous layer, and using scarf joints means half the number of angles to using equal angles each side of the block. Half the angles means the cumulative error is going to be less if anything is off (in theory). The wood I have is a not really as deep as I would like, and doing it this way means initially I only need to get one side and one face squared. The other face can be fixed after gluing the segments. I don't have to worry about the length or width of each segment providing they are above the minimum requirement. On the downside, the glue-up is tricker as I found out later. So here is how it works out in sketchup 11 inch segmented rim using 45 degree scarf joints First off, I trued up t...

I was a bit nervous about 14 shoes being able to handle the tension, so I decided to re-model the bracket band with 18 shoes. This time I left a larder space between two of them to accommodate the neck, then evenly spaced the shoes around the remainder of the circumference. new bracket band model with 18 shoes For comparison, here is the old model. No idea why the colours are reversed, there's probably a logical explanation somewhere. old bracket band model with 14 evenly spaced shoes