Thermal Printer Brain Transplant is Two Hacks in One

You know how sometimes you just can’t resist collecting old hardware, so you promise yourself that you will get around to working on it some day? [Danny] actually followed through on one of those promises after discovering an old Radio Shack TRS-80 TP-10 thermal printer in one of his boxes of old gear. It looks similar to a receipt printer you might see printing receipts at any brick and mortar store today. The original printer worked well enough, but [Danny] wasn’t satisfied with its 32 character per line limitation. He also wanted to be able to print more complex graphics. To accomplish this goal, he realized he was going to have to give this printer a brain transplant.

First, [Danny] wanted to find new paper for the printer. He only had one half of a roll left and it was 30 years old. He quickly realized that he could buy thermal paper for fax machines, but it would be too wide at 8.5 inches. Luckily, he was able to use a neighbor’s saw to cut the paper down to the right size. After a test run, he knew he was in business. The new fax paper actually looked better than the old stuff.

The next step was to figure out exactly how this printer works. If he was going to replace the CPU, he was going to need to know exactly how it functioned. He started by looking at the PCB to determine the various primary functions of the printer. He needed to know which functions were controlled by which CPU pins. After some Google-Fu, [Danny] was able to find the original manual for the printer. He was lucky in that the manual contained the schematic for the circuit.

Once he knew how everything was hooked up, [Danny] realized that he would need to learn how the CPU controlled all of the various functions. A logic analyzer would make his work much easier, but he didn’t happen to have one lying around. [Danny] he did what any skilled hacker would do. He built his own!

He built the analyzer around an ATMega664. It can sample eight signals every three microseconds. He claims it will fill its 64k of memory in about one fifth of a second. He got his new analyzer hooked up to the printer and then got to work coding his own logic visualization software. This visualization would provide him with a window to the inner workings of the circuit.

Now that he was able to see exactly how the printer functioned, [Danny] knew he would be able to code new software into a bigger and badder CPU. He chose to use another ATMega microcontroller. After a fair bit of trial and error, [Danny] ended up with working firmware. The new firmware can print up to 80 characters per line, which is more than double the original amount. It is also capable of printing simple black and white graphics.

[Danny] has published the source code and schematics for all of his circuits and utilities. You can find them at the bottom of his project page. Also, be sure to catch the demonstration video below. Continue reading “Thermal Printer Brain Transplant is Two Hacks in One”

Game Boy printer USB cable and software

[Furrtek] hooked up his Game Boy printer for use with a PC (translated). The two-part hack started with a cable to attach the device via USB. A Nokia interface cable was used as a base to translate the USB signals into serial, and an ATtiny45 microcontroller added to talk to the printer. He did a great job of free-forming the circuit alterations and fitting it back into the plastic USB plug housing.The next step was to write some software. Using VB6 he coded an application that loads in an image, scales it to fit, and allows you to adjust the contrast that the thermal printer produces. For testing purposes he’s reusing old receipts. See it in action after the break.

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Arduino Thermoscanner

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[Steve] sent in a tip to show us his Thermography scanner. Constructed from an Arduino, two servos, a thermal sensor and a little bit of code, it is fairly simple. The results aren’t groundbreaking. You can see his examples are fairly low resolution and took about 30 seconds to capture. It isn’t bad for a quick project though. The source code is available on his site.

Diamond thermal paste

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[Jared Bouck] over at InventGeek  writes about his experience making his own thermal paste. Diamonds can be up to five times as thermally conductive as silver, the primary ingredient in most popular thermal compounds.  He combines 60,000 mesh diamond dust he ordered off eBay with non-conductive silicon grease using a special mixer he constructed to keep down the dust. After some experimentation he achieved a max load temperature of 38 degrees Celsius versus a leading silver paste’s  temperature of 57c on the same system.

Poor man’s thermographic camera

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Using an IR thermometer, there are two ways to go about building a thermographic camera. The first uses a pan and tilt head. Scan lines are emulated, as a computer controls panning from left to right, taking a temperature sample from each step. Vertical resolution is accomplished by tilting. Another method uses a web cam attached to the thermometer. The thermometer’s laser pointer is captured with temperature annotations, as the computer records the field of view. We think the best outcome can be found with a combination of both methods. The video embedded below demonstrates the results. This would be a good addition to the Autonomous paintball sentry.

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