Bistable 555 Circuit

Last updated: 23 Feb 2014 - 21:16

Basic toggle function starts in the "off" state implemented with a 555.

555 Bistable Schematic: Basic toggle function starts in the "off" state implemented with a 555.

I'm working on a power supply design and I wanted to have the output on/off button just a momentary push button. The main reason for this was to make sure that the output was always off when the power came back on. You don't want to have the output get knocked on whilst moving the power supply and accidentally put too many volts into a prototype!

toggle button

This, Jen, is the Internet

Last updated: 02 Nov 2013 - 14:22

This, Jen, is the internet.

The Internet: This, Jen, is the internet.

For OggCamp this year I had the idea of taking along a replica of The Internet from the British TV series The IT Crowd. If you haven't seen the episode, it revolves around a clueless IT manager being selected as the employee of the month. As employee of the month she is expected to make a presentation to the shareholders about her area of expertise. Keen to show her up, the two support guys manage to convince her that a small black box with a red flashing light is actually the Internet.

The box has become a favourite amongst fans of the program with dozens of versions of it having been built. It even made a brief appearance in the final episode of the series broadcast earlier this year.

The internet,
IT Crowd,
Raspberry Pi

OggCamp 13: Forking Hardware!

Last updated: 19 Oct 2013 - 09:31

This year at OggCamp I presented on using version control to manage hardware projects. It's something I think will be really important as the barrier to spinning a new hardware design gets lower and lower. Below are the slides from the talk I did.

3D printing,

3D Printed Nativity Set

Last updated: 27 Nov 2012 - 12:48

All the figures included, printed and then painted.

3D Printed Nativity Set: All the figures included, printed and then painted.

This is nearly a year old now, but by the time I finished it last year it was too late for anyone else to have a go, so rather than publish just after Christmas and have it forgotten I sat on it for nearly a year. I was looking for a small Christmas themed plastic model to put in home made crackers for family. In the end I came up with the idea of designing a minimalist nativity set which once everyone pulled their crackers could all be assembled. It all went down well with both my family and Katie's.

3D printing,
Christmas decoration

Laptop Battery to Phone Charger

Last updated: 28 Aug 2012 - 21:15

Laptop battery and 5v regulator with dual USB port outputs.

Portable Phone Charger: Laptop battery and 5v regulator with dual USB port outputs.

I went camping at a festival this weekend, this meant 3 days in a tent with no power. Of course there are charging facilities at such an event, but they're not free and you can't charge your phone while you're asleep like at home. Previously I built a one charge boost charger to let you charge up a phone on the go, but that's only good for one charge of a modern phone and then it needs charging itself. I was camping with my wife for three nights and we both have modern Android phones which we used a lot so we needed 6 full charges over the course of the weekend. Looking around the lab here before we went I spotted the old ASUS EEE PC 701 extended battery and realised that would probably be quite a big capacity.

Battery charging,
field hacks,
laptop batteries,

OKI Metcal PS-900 Soldering Iron Review

Last updated: 28 Aug 2012 - 13:41

The complete OKI PS-900 kit (plus a couple of extra tips).

OKI PS900: The complete OKI PS-900 kit (plus a couple of extra tips).

Having a really good soldering iron can really affect the range of parts you can use in projects and the time it takes you to do things. I've been using a Weller TCP iron that was originally owned by Tektronics for many years and it has been a great tool (and still is!) but upgrading this to lead free can be pricey and the temperature control in these old mechanical irons can make switching from soldering pads connected to hairline tracks to pads connected to ground planes a little dangerous for the components. I had a couple of bits of 0.5mm pitch soldering to do, so before I got started I decided to get a new lead-free compatible iron. After some research I settled on the OKI PS-900 soldering station.

surface mount,

Announcing the OggBox Project

Last updated: 14 Aug 2012 - 22:03

The OggBox is a simple, hackable open hardware music player. It's a pocket sized device, about the size of a smart phone which can play or record open formats to or from an SD card. It will support Ogg Vorbis, FLAC and WAV files, but has only been tested on Ogg so far. The hardware was designed in KiCAD and all the files are available to download and use (CC-BY-SA).

Open Hardware,
Open Source,

Schmart Board Review

Last updated: 10 Jun 2012 - 21:10

A small STM32 processor broken out to 0.1" pitch.

48 pin LQFP: A small STM32 processor broken out to 0.1" pitch.

There are lots of cases these days where the chip you want to play with are just not available in a through-hole variety. This is a real nuisance for hobbyists and even professionals who want to prototype a sub system before designing the PCB. You can get custom PCBs in small volumes very cheap these days but sometimes you lack the time or skills to make a custom PCB for simple jobs. There are a few suppliers of break out boards but they tend to be wildly over-priced cheap small PCBs with nothing remarkable in terms of features. SchmartBoard seems to be different, a few weeks ago I go sent a package of them for review and decided to look into what makes them special.


Derby Mini Maker Faire 2012

Last updated: 05 Jun 2012 - 14:36

I was at Derby Mini Maker Faire this weekend and really enjoyed the day. Got a few bits to tinker with from some of the stalls and saw lots of interesting projects. I was hanging around the Bristol Hackspace stand for a good chunk of the day and we had a few interesting projects on display. The now famous musical bicycle wheels, Barney had his twitbeeb project running which provided a twitter fall on a BBC model B using a Raspberry Pi. My Pong 2 game was on display as well. London Hackspace had an enormous crazy golf course built all around the hackspaces area. A robotic xylophone from Brighton was playing most of the day and there were occasional appearances from a Dalek.

Maker Faire,
Bristol Hackspace

Pong Version 2 and vgalib for ChipKIT

Last updated: 27 May 2012 - 12:19

I've finally got around to making the VGA driver into a library that doesn't require all that messy interrupt code in the main sketch. The actual operation is along the lines of the pixel based display used in the life games but I've re-implemented Pong with this new library as a test.

The schematic for the pong demo is the same as the original. The main code is much simplified by the interface that the library gives. I've added a count down to the start and a game over screen which has a QR code that links here. The example shows off all the methods currently available in the library.

The source code is in the examples folder of the VGA library along with some python scripts that were used to generate the bitmaps for the blit operations that generate the final game screen.

All the source and library are maintained on GitHub vgalib.



Email: nathan@nathandumont.com

Mastodon: @hairymnstr@mastodon.social