Project GeigerFox

IMG_7623If you have been following me on twitter you may know that I have been working on a Geiger counter. As that project is starting to become complete I felt appropriate to start a  blog post about it. So, how did I get the idea and carry it through the project? Read the story! Continue reading

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C64 XA1541 Cable

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The XA1541 cable is adapter often used to connect C64s 1541 floppy drive to more modern PC equipment. It connects to PC parallel port, and special software bitbangs IEC commands and data to 1541 drive. Old 386 laptop is used … Continue reading

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VFD Returns!

IMG_5250I dug out my old VFD display project. This time I got some text showing up and prototype ready to be even bolted in some enclosure. I started with sawing piece of from original display controller as I didn’t bother to make PCB to house VFD screen, and all needed IC:s and connections were already there. Removing piece from 2mm fiberglass board is not easy task when your only tools are couple of hobby knives. But sawing boards with hacksaw would have caused more nasty fiberglass mess.  Continue reading

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UART to RS232 voltage level shifter

IMG_3577Sometimes I find myself in need of interface some old tech that uses legacy RS232 interface. The thing is today’s computers and other smart logics do not have real TIA-232 compliant serial ports. The RS232 standard uses voltage levels that range from ±3V to ±15V, and space between -3V and +3V is defined as not valid. And a logic 1 is transmitted as negative voltage.

Even though use of RS232 ports are seldom use anymore, an asynchronous serial communication is not dead. Many embedded systems use it as debug interface. Also some devices still use it as communication interface, even if physical layer is implemented with USB or Bluetooth.  Continue reading

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Saleae Logic analyzer knock-off

IMG_3296Postman (or woman) brought envelope containing Chinese Saleae Logic analyzer today. Lets see if fierce 20€ price is justified for this plastic brick. I also tried to reverse engineer one Sony VAIO wireless keyboard which may be more difficult that it first seemed. Continue reading

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Still ticking

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Front panel awaits to be replaced with aluminum panel, if I ever get it somehow machined.

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Watch project

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Happy first birthday for this blog!

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Sharp Elsimate EL-8118

IMG_2497As you might have noticed, I have a thing about VDF displays and old calculators. This time I found old Sharp EL-8118 which is pocket calculator with basic arithmetic operation with some nice additions. It includes features like settable floating/fixed decimal, sqrt’s and powers, percent and delta percent, constant pi, 1/x or x^(-1) and memory.

It had had battery leak in somewhere its lifetime, but nothing was damaged bad enough and cleaning switch & battery contacts fixed it. It has wear and scratches, but is still sturdy and beautiful calculator. Continue reading

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Working serial connection!

hello world

I got the Hello World! Finally serial communication part is working, next part is to get display refreshing and sift register writing to work efficiently as it must be constantly multiplexed.  Continue reading

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