DIY kit computer

[SouthernComfort]

DIY kit computer goes Forth against Braben's RaspberryPi


Elite developer David Braben's RaspberryPI may have generated headlines aplenty, but it's not the first 1980s-style teach-yourself-programming gadget, one Reg reader insists.
Step forward Julian Skidmore, developer and seller of FIGnition, a 20 quid DIY "retro computer built with modern parts... designed to be built by its users, coded - it boots into its programming language - and understood".

"The key thing to producing programmers in kids is that you need ridiculously simple computers, with Kilobytes of memory and relatively modest performance," says Skidmore.
"It's simplicity that produces understanding, ability and excitement."
Simplicity? Try 8KB of memory, 384KB of Flash storage and an Atmel AVR 8-bit microcontroller as a CPU.
Keyboard? That 2 x 4 array of buttons on the right-hand side are your eight data-entry keys.
FIGnition is a kit computer comprising motherboard and solder-yourself components. There's a USB port for power, and a phone-style PAL video output so it can be hooked up to a telly as a monitor.
Just like it used to be...

Unlike the mass of early 80s home computers - but familiar to anyone who played with a Jupiter Ace all those years ago - FIGnition boots into a Fourth Language interpreter.
Skidmore promises to open up the hardware at the end of the month for folk who really want to do it themselves, though he's selling kits too.

https://sites.google.com/site/libby8dev/fignition

[setfiretorain]

I'd loved to have understand that.

[SouthernComfort]

I'd loved to have understand that.

Grammar or concept?
Was a direct quote, a self build, micro computer, using an AVR microcontroller. Anyone who is familiar with these units will tell you they are useful for any number of things. Rip off the design, use your own components, quite a nifty gadget.

[chroma]

Ive got an ATmega128, its a whole lot of fun to mess around with

[setfiretorain]

Concept mate!

[SouthernComfort]

Ive got an ATmega128, its a whole lot of fun to mess around with

Nice, buy or build?, I think its a great concept, could be easily modified or enhanced to suit your needs.

Concept mate!

Google is your friend on this one, have a look at link and what Chroma said.

[chroma]

bought, its just the microcontroller, had an idea for an underwater mini sub for surveying some waters i fished. still in its concept stages.

[SouthernComfort]

bought, its just the microcontroller, had an idea for an underwater mini sub for surveying some waters i fished. still in its concept stages.

Are you Bear Grylls ? Have seen them do all sorts, like the DIY aspect. From reading designer plans to open it up for people to mess with but as I said could rip off the design and do your own thing.

[chroma]

i ran into a few problems early on.

My initial idea was to take a grinder to a fire extinguisher to slap all the gear in, fit some heavy duty perspex to make it withstand a fair few atmospheres, build a housing out of pvc pipe with a small pump and valve to allow variable buoyancy and protection around any wreckage or rock formations, also a place to mount the impellers and lamps.

I planned on fitting an old web-cam and overlaying a digital compass via the ATmega and adding some accelerometers to gauge speed and stabilise / account for roll, pitch and yaw, a barometer to gauge depth and the like (the rationale being the deeper I went the more the internal air pressure would increase) essentially run everything through this little microprocessor.

The problems i wound up with was cabling. trying to drive voltage via DC down a few hundred metres of cable doesnt work too well...
That and finding a digital compass with decent white-papers and also hitting budget... less than straight forward, everything i found seemed to be obsolete and no longer manufactured, anything nowadays seems to draw way more amperage than id like :/
Basicly the technical problems racked up really fast, the concept is solid enough its just sourcing parts and hacking up some workarounds thats the issue...
I'll finish it one day, but i've not been fishing at all this year.

[SouthernComfort]

I would scrap the extinguisher idea, harder to work with than it needs to be. PVC would be more than adequate. Think this design sounds similar to what your after. Hope its ok to post.





Welcome to Rollette.COM

[chroma]

PVC wouldn't stand up to the pressures of any real depth, theyre good to like a dozen ATM before they fold.

The extinguisher should be easy, strip the valve and gubbins, take an angle grinder to where the top begins to curve.
Cut a shallow channel with a decent routing bit around the grinded face (to allow for a nice tight gasket)
Make two corresponding plates (i was thinking octagonal) one from 1/4inch steel plate the other from seriously thick 12mm polycarbonate bore holes on each of the 8 faces.
Drill a decent sized center hole into the steel to account for the bottom curvature of the extinguisher and weld it on.
Fire through some threaded steel rod, slap a gasket on and then bolt the lot together.

This has the added bonus of making the chassis an easy ground source for the electrical internals and being able to weld brackets to support the pcbs
I was even considering 3 steel plates (1x 1/4" and 2x 1/16")
with the two sixteenths with a holes almost the diameter of the opening, weld one centrally onto the end of the extinguisher (therefore increasing the gasketable surface area, then sandwiching polycarb between it and the other sixteenth, slap on some silicone and voila, should be able to handle some serious depth and combat the front tilt from the buoyancy of the polycarb.

Was even toying with making a few ballast tanks from Sigg bottles that could be jubilee clipped (~~~~ trying to weld steel and aluminium together) onto the threaded bars, making skids from pvc pipe that could be bolted directly to the bars and having the whole thing somewhat modular to be easily maintainable and replacement.

Ive got most of the gear, its just working the kinks out of the initial design that's held me back from going mental with a grinder and mig.

Thought about hacking up some wifi gear and simply remote controlling via a single copper wire to work around the headache of wire lengths, 640x480 res and telemetry should be easy to bounce back via wifi and i could simply use conventional RC gear for the bulk of control work.

Like i said, its an idea thats been rattling around my head for a while now, but other obligations are keeping me from jumping in at present :/

[SouthernComfort]

Did you check out the link?, I believe someone has gone to the trouble of calculating the pressures at depth. Might not be exactly what you are looking for but contains a wealth of information regarding the subject.

[chroma]

Did you check out the link?, I believe someone has gone to the trouble of calculating the pressures at depth. Might not be exactly what you are looking for but contains a wealth of information regarding the subject.

yeah but hes not given any kind of values...
absolute pressure for instance isn't scaled to anything, I know its not psi cause its roughly 30psi per atmosphere (it varies with different waters)
Initial depths will be on average of 200m (the depth of my local test loch) so I'm looking at pressures of 310psi or 22kg per cm?
Some of the areas ive been looking at are well over the 500m range where pressure gets seriously problematic :/
Not that the pcv would fold at that depth but leakage from multiple joints gets to be an issue.