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.  Read More …

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.  Read More …

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. Read More …

VFD Schematics & code witchcraft

I have yet published basic schematics and code for display project. VFD controllerAtmega 16 work as display controller. It will read data from uart serial port, place it to text buffer and simultaneously  multiplex display trough segment voltage buffers and huge digit shift register. ASCII text is converted to segment data and font can be created with computer program. Read More …