Animating An LED Matrix Without A Microcontroller

February 9, 2011 by Mike Szczys 20 Comments

[Konstantin] had some extra 27C256 EPROMS lying around and decided to use them to animate an 8×8 LED matrix. He’s not only using them to store data, but driving the display with them as well. The chip holds 32 kilobytes of data which equates to 4096 frames of animation. A 32 kHz clock circuit works with some ripple counters to scroll through each byte of stored data, turning on the columns while sinking the proper row. Of course current protection is a must so there is a ULN2308A darlington driver and some 2N2907 transistors at work, but you won’t find a programmable microcontroller. Neat!

Yep, you read that right. The picture above shows an EPROM chip that requires a UV light source to erase the data.

[Thanks Kopfkopfkopfaffe]

DIY Clapper

February 7, 2011 by Kevin Dady 11 Comments

[Patrick’s] latest Instructable walks us though making a clap clap on / clap clap off type of switching circuit, similar in use to that sometimes popular commercial product seen on TV. He does this by using a standard electret microphone, half of an LM324 op amp, a voltage comparator and a PIC micro controller.

The operation of the device is as simple as its wiring, the microphone picks up sound and produces a signal, that signal is stripped of its DC component and fed into the op amp, after 2 stages of amplification the signal passes though a voltage comparator, and if the sound was loud enough a timer is triggered on the pic. Two claps within the specified amount of time, the micro then switches on a relay which can toggle your outside appliance (keeping the load in mind).

On the last page [Patrick] also gives a rough outline of how to make a single clap on / off variant using a 555 timer and some flip flops. Join us for a quick video after the break, and be sure to check this one out.

Continue reading “DIY Clapper” →

Analog Computer Does Math

February 4, 2011 by Mike Szczys 14 Comments

This analog computer can multiply, divide, square numbers, and find square roots. It has a maximum result of ten billion with an average precision of 2-3%. [Miroslav’s] build recreates something he saw in a Popular Electronics magazine. It uses a resistor network made up of three potentiometers with a digital multimeter is an integral part of the machine. To multiply a number you set the needles on the first two knobs to the numbers on which you are operating. To find the result turn the third knob until the multimeter has been zeroed out and read the value that knob is pointing to. It seems much more simple than some of the discrete logic computers we’ve seen, yet it’s just as interesting.

Emulating Ink Cartridges

February 2, 2011 by Caleb Kraft 15 Comments

[Smartie_on_computer] wanted to do some experimenting with an epson printer. After getting a somewhat disassembled one, the first step was to simply get it running. Unfortunately, one of the ink cartridges was missing and these printers refuse to do pretty much anything without all the cartridges installed. Rather than go purchase a costly cartridge that they didn’t intend to actually use, [Smartie_on_computer], chose to emulate the cartridge using a microcontroller. After some searching for the protocol used on the cartridge, the info ended up being in the patent. [Smartie_on_computer] now has a functional printer that is destined to be a 3d printer in the near future. You can see a video breakdown after the break.

Continue reading “Emulating Ink Cartridges” →

Fabulous Magic 8 Ball Prank

January 28, 2011 by Caleb Kraft 37 Comments

Hackaday forum user [arfink] has shown us a brilliant practical joke he built. This is a magic 8 ball that will blind you with a flash when you flip it over. Have you ever been in a room with one of these and not flipped it over? Neither have we. Using a basic flash circuit ripped from a disposable camera in conjunction with a mercury switch, this project took him about 2 hours to make. Admittedly, most of that time was just trying to split the 8 ball in half without completely destroying it. The circuit is pretty simple. Just figure out what 2 wires need to be crossed to trigger the flash and install your tilt switch there. He added a power cut off so you could disable it as well.

UPDATE: video added after the break! Continue reading “Fabulous Magic 8 Ball Prank” →

Converting 8mm Film To Digital

January 15, 2011 by Caleb Kraft 24 Comments

Many of us have these old 8mm family videos lying around and many of us have lamented at the perspective cost to get them converted to digital. [Paul] came up with a pretty slick way of digitizing them himself. He cracked open an 8mm projector and replaced the drive motor with one he could run at a much slower speed, allowing him to be able to capture each frame individually with his digital camera. He’s rigged his remote shutter control to the shutter of the projector so that it would be perfectly synchronized. There’s a video of it in action on the flickr page, and a video of the full 16,000 frame clip after digitization here.

[via Make]

Making Punch Card Programming A Snap

January 6, 2011 by Mike Szczys 47 Comments

About thirty years ago [H. P. Friedrichs] pulled off a hack that greatly improved the process of programming with punch cards. At the time, his school had just two IBM 029 keypunch machines. One of them is shown in the upper right and it uses a keyboard to choose which parts of each card should be punched out. This was time-consuming, and one misplaced keystroke could ruin the card that you were working on. Since you had to sit at the machine and type in your source code these machines were almost always in use.

But wait, the school acquired a dozen of the TRS-80 computers seen in the lower left. They were meant to be used when teaching BASIC, but [HPF] hatched a plan to put them to task for punch card generation. He built his own interface hardware that connected to the expansion port of the new hardware. Using his custom interface a student could create a virtual card deck that could be rearranged and revised to correct mistakes in the source code. The hardware then allows the virtual deck to be dumped in to the punching machine. This broke the bottleneck caused by students sitting at the punch card terminal.

We think that [HPF] sent in this project after seeing the antiquated hardware from that 1970’s calculator. These hacks of yore are a blast to revisit so don’t be afraid to tip us off if you know of a juicy one.