Asteroids Mini Arcade Machine

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Here’s a tiny Asteroids arcade machine I built from scratch. It uses a vintage 3″ round cathode ray tube driven from an amplifier board and high voltage supply of my own design.

A friend of mine ported his 6502 emulator to an STM32F4 Discovery board so this arcade machine is able to run the original Asteroids program without any modifications. The STM32F407 processor has two DAC outputs which work perfectly for driving the X and Y deflection inputs on the amplifier board.

Turns out the ST Micro part is really good for driving displays like this. Not only do the DAC outputs work great for deflection, but the hardware floating point really speeds up things like 3D vector rotation.

Come find me at the Bay Area Maker Faire! (May 17 and 18–go buy your tickets now!) I will be located in the Fiesta Hall (the dark room with the Tesla coils). I’ll set up a second arcade machine running some additional demos, including a Super Secret Game. You’ll just have to come and find out what it is.

Three Fives – Discrete 555 Timer

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My friends at Evil Mad Scientist have a new kit for sale. It’s a 555 timer circuit that you can build yourself using discrete transistors. You can wire it into all sorts of 555 timer circuits and then probe individual nodes to see how the chip actually works.The circuit board that you get with the kit has silkscreen labels that mark the functional blocks of the circuit, and silkscreened component designators that match up with the “official” Signetics schematic.

The circuit is full of interesting analog electronic design elements. You’ll be able to play with differential pairs, current mirrors, Darlington stages, diode-connected transistors, and more.

It’s a great kit if you want to learn more about how integrated circuits work, or if you’re a fan of the indefatigable 555 timer and want to have a neat conversation piece, or even if you’re just a beginning electronics hobbyist and you want to practice your electronics assembly and soldering skills.


CRT Driver Kit Update

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It’s been quite some time since I last posted about this. The project has been on the back burner for some time now since I’ve just been so busy with other things. It’s actually pretty far along the process but the cost of the parts is just too high, and the kit has quite a few parts.

I’ve been revisiting the design again to see if I can make it easier to build and less costly.

A question: Would you consider a version without a DAC? Instead of having an 8-bit digital interface (Arduino compatible), it would have analog X and Y inputs and a video/blanking input.

Quick Note

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If the site’s been very slow for you lately, it’s because someone used a PHP injection attack to add some potentially malicious Javascript to the top of the page. It should be fixed now. Thanks to Olli for the tip.

Panaplex Wall Clock Schematic and Software

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Remember my Panaplex clock project? Here’s a present: the design details!

Panaplex Clock Schematic
PIC18F242 listing – main.asm

Still Alive

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Wow, it’s been a few months since my last post. Sorry for the blog silence. I got very busy with a new job and just haven’t had the time to work on projects at all, let alone blog!

So here’s a quick one–it’s a Heathkit GC-1005 digital clock that uses Panaplex displays (Neon filled). I picked it up at the electronics flea market and it looked like someone had been trying to get it working before me, and they left a bit of a mess. I had to clean up the wiring job and check the electrolytics to make sure they were still good (they were).

The reason it wasn’t working right is that some of the component leads on the bottom of the PC board had poked through a paper insulator and shorted out against the switch contacts on the bottom of the case. All I had to do was trim the component leads and fix the insulator.
Heathkit GC-1005 Clock

A CRT Driver Board Kit?

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At Maker Faire, a lot of people asked me if I had a kit available for any of my CRT clocks. Based on the amount of interest, I’ve decided to put together a kit that will make it easy for people to drive cathode ray tubes using simple digital or low voltage analog control signals. The kit will include a PC board and all the components as well as detailed assembly instructions. For people that opt to use the digital interface, the kit will also include source code libraries making it easy to generate simple vector graphics.

The kit will use surface mount components, but none smaller than 0805. The ICs will be SOIC or SOTs, with the exception of the DAC, which is TSSOP.

Because this would be the very first surface mount kit many people attempt, I’m trying to figure out an approach for the assembly instructions that will make it easy to succeed. Some ideas I’ve had so far are:

  1. Solder the DAC first since it has a fairly fine pitch package (TSSOP). The kit might include a second DAC as a spare. By soldering it first, it’s easier to check for short circuits and open circuits. Another approach is to make a “spare parts kit” available that has some of the commonly “blown” parts.
  2. Assemble the kit in sections, testing the circuit a piece at a time. For example, after assembling the DAC, you would assemble the filament power supply and then test it to make sure it works and outputs the proper output voltage.  This makes it easy to correct any mistakes as they occur. I don’t want people to assemble the whole board, throw the switch, and not have a working kit–or worse yet, have the kit go up in smoke.
  3. It makes sense to release the assembly instructions on a site like Instructables, where it’s easy to include detailed macro photos of critical assembly details (like diode orientation). It also makes it easier to correct the instructions for mistakes, and it avoids the environmental impact of including printed instructions with the physical kit.

Hobbyists seem to have an aversion for surface mount components. With a little practice, I’ve found that it’s faster and easier to use surface mount components. Think about all the time you could save by not having to bend and clip resistor leads. You can solder most of the components without having to flip the board over.

If you have any ideas, please feel free to comment. This is all still in the early stages so there is plenty of room to change things and try new approaches.

Maker Faire 2011

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The Maker Faire is a neat DIY convention that happens every year. I’m bringing some of my projects to the Maker Faire Bay Area; just look for Tube Time. Come and say hello!

New CRTs

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The other day at the electronics flea market I obtained a couple of new CRTs. The one below has a P2 phosphor which is brighter and more energetic than the P1 and has much longer persistence. You can light it up with one of those UV LED flashlights. Notice the inspection sticker.

New CRT - 3JP2

And the one below is a fine example of the P12 phosphor–it lights up amber. The color is similar to that of the old amber MDA monitors but the persistence is longer.

New CRT - 3JP12

Maker Faire 2010

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Hello to everyone from the Maker Faire! It was great meeting you all in person. But if you missed out, here are a couple of pictures to give you an idea of what the event was all about:
Maker Faire 2010 - Tesla Concert

Maker Faire 2010 - Tesla Concert

Maker Faire 2010 - Gamelan

Maker Faire 2010 - Big Wheels

There are many more pictures in the MAKE Flickr Pool. The entire San Mateo expo center was jammed with crazy, cool, weird, and wild exhibits, projects, vehicles, and people!

My friend Jeri recorded some video of my exhibit, so take a look if you couldn’t make it to the Faire.

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