Retrofitting A 60-year Old Electric Heater

October 10, 2011 by Mike Nathan 22 Comments

electric_heater_retrofit

[John] found an old Kenmore electric heater at a junk store one day, and thought it would look great in his bathroom. The only problem with the unit is that it was built back in the 1940s/1950s, so it lacked any sort of modern safeguards that you would expect from an indoor heater. There was no on/off switch, no fuse, no thermostat, and no tip switch – though it did have a nice, flammable cloth-covered power cord.

Since [John] wasn’t too keen on burning his house down in the name of staying warm, he decided to retrofit the old unit’s shell with a new ceramic heater. He found a $20 unit that looked like it would fit, so he disassembled both heaters and got to work. The Kenmore’s innards were scrapped, then he gave the unit a nice fresh coat of high-temp paint. The new heater was cut to fit inside the old unit’s shell, controls and safety features intact.

He says that it works very well, and that it looks great in his bathroom. If you’re considering doing something similar, be sure to check out his writeup – it is very thorough and has plenty of details that will help you along the way.

A Masochistic Video Card

October 6, 2011 by Brian Benchoff 24 Comments

Have a penchant for pain? Why not destroy your fingertips with a wire-wrap tool building a video card made entirely out of discrete components.

When [Chris] decided to build an entry for the Dangerous Prototypes 7400 logic competition he already had his hands full. The 74xx chips he had on hand had a maximum clock frequency of 25MHz, but the VGA pixel clock runs at 40MHz. dividing the H sync timing by 4 means the maximum speed required of the video card is only 10MHz, albeit with a reduced resolution.

The video card was constructed on perfboard with wirewrap sockets. An 8-bit DAC was included, allowing the card to display 256 separate colors but only the three primary lines were wired up to the VGA cable. As is, the card cycles through 8 different colors in a constant loop, not bad for a pile of chips.

VGA out has been done on everything from an ARM to an ATtiny, but rarely, if ever, has VGA been done with discrete components. While this video card may not be our first choice for bitcoin mining, it’s still a very impressive build. Check out the walk through video after the break.

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Very Impressive Steampunk Keyboard

October 4, 2011 by Brian Benchoff 31 Comments

After spending more than 250 hours on his project, [Admiral Aaron Ravensdale]’s steampunk keyboard is finally done.

The keyboard mod was designed around a Model M. After removing the keycaps, [The Admrial] upcycled the keys from old Continental typewriters. Because his typewriters only had 47 keys and the Model M needs 104, three typewriters needed to be sourced off of eBay. Polishing the metal rings of the typewriter keys ate up more than 100 hours.

After building a brass frame from 8mm tubing and candle holders, the stained wood inlay was drilled for the keys. Status lights were installed and the PCB was connected. A pair of ‘gaslight’ keyboard lights were fabricated using 3mm tubing and very fitting “Golden White” LEDs.

[Admrial Ravensdale] put up an Instructable walking through the build process of his keyboard. There’s also a German-language PDF build log that shows every picture of every step.

This isn’t [Admrial Ravensdale]’s first Hack A Day feature, but with a build that might one-up the original steampunk keyboard we can’t wait to see what comes out of [The Admiral]’s workshop next.

Resurrecting An XT

October 3, 2011 by Brian Benchoff 28 Comments

The best laid plans of mice and men oft go awry. At least that’s what we’d tell ourselves if we couldn’t find a 30-year-old computer monitor. [Andrew] picked up an old IBM XT on eBay recently and tried to get the video working. He hasn’t seen any success yet, but the way he goes about solving this problem is very clever.

[Andrew] was stuck with a cool old computer with no way to output anything onto a screen. The XT had an MDA port but neither his TV nor his VGA monitor would accept MDA frequencies. As a workaround, [Andrew] connected an Arduino to the XT keyboard port. On the factory floor, IBM workers used the XT keyboard to load code onto the machines while POSTing. He was able to change the frequency of the MDA CRT controller to CGA frequencies, and with the help of some small components got some video working.

The Hsync and Vsync are still off, and [Andrew] hasn’t been able to get the machine to finish POSTing, but he figures he can use the XT keyboard port for bidirectional communication. He’s written a very small kernel to test out a few things, but unfortunately the XT’s power supply died recently. Once [Andrew] replaces that, we’re sure he’ll get his box up and running.

Recreating The First PC

September 30, 2011 by Brian Benchoff 11 Comments

If you’re looking for a simple Ardunio project, why not replicate the first personal computer?

After discovering the Arduino, [Mark] realized recreating really old computers would be a fun project. An Altair 8800 was on the table, but the sheer number of blinkenlights, switches and the Intel 8080 CPU made that a fairly difficult project. After a bit of searching, [Mark] discovered the Kenbak-1, widely regarded as the first personal computer. The Kenbak also had the added bonus of having a very minimal I/O compliment and was built entirely with TTL components.

Since the Kenbak-1 is an extremely simple computer, [Mark]’s build ended up being fairly minimal. The schematic is only an ATmega328, a few shift registers and a real-time clock for a few added features the OG computer didn’t have. The completed build is programmed by pushing buttons to enter machine code into the mega’s RAM and then executed. [Mark] has a few programs already figured out – a program that counts in binary, a ‘Cylon eye’ and a BCD and binary clock. While the Kenbak-uno doesn’t have the awesome vintage case of the original, it’s still a remarkable build.

Check out the videos after the break for a walk through.

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Booting A 1989 Mac With Mario

September 29, 2011 by Brian Benchoff 11 Comments

As a new recruit to the 68k Macintosh Liberation Army, [dougg3] is really showing off his hardware hacking ability. He came up with a replacement ROM SIMM for his Mac IIci and made it play the Mario theme on boot instead of the normal chimes.

Swapping out the ROM in these old macs isn’t an uncommon procedure. On some 68k machines, there’s a SIMM slot to either replace or expand the soldered ROM. In fact, it’s fairly common to take the ROM SIMM out of a IIsi and put it in the king of kings computer to make an SE/30 32-bit clean. We’ve never seen a re-writable ROM SIMM for these old macs, so we’re pretty sure [dougg3] just spared a Mac IIsi from the dumpster.

Now that the entire 68k Liberation Army is clamoring for one of [dougg3]’s re-writable ROMs (we’ve got cash), the question of what to do with it comes up. Of course, SE/30s can now be 32-bit clean without installing MODE32 and new startup chimes can be added. We’d really like to see some hard-core ROM hacking going on, like installing a 68060 in a Quadra 950.

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Capacitive Sensing Tutorial

September 26, 2011 by Brian Benchoff 13 Comments

[Bertho]’s submission for the 74xx logic contest is really impressive. He designed a capacitive sensing touchpad using only 74xx and 40xx logic chips. We’re impressed with the build and his writeup is one of the best resources we’ve ever seen for capacitive sensing.

There are two ways to go about designing a capacitive touchpad. The first option is put a voltage through an RC circuit. Measure the voltage-time curve, and you have a measure of the capacitance of the circuit. The second method is setting up an RC circuit to change polarity after a threshold for C has been reached. Microprocessors only use one of these methods (AVR uses the first, PIC uses the second), but [Bertho] decided to implement both methods for unknown reasons we still respect.

The circuit [Bertho] designed has a 30MHz clock using only 74xx logic chips, an amazing feat in itself. An 8×8 channel panel was fabricated and the whole build connects to a computer over RS-232.

The finished build is good enough has 64 points of resolution and is able to detect proximity very well. The touchpad is even able to recognize when a pen is placed on the panel. Check out the video after the break for the walk through and demo of this amazing build.

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