New toys

I “found” some old DELL PowerEdge 2850 rack servers. 2x 3.2Ghz intel xeon (P4 generation), 8GB memory, and bunch of 146GB and 74GB SCSI HDDs.

I don’t have use for these yet, but maybe something comes up.

How to fix moody Arduino nano

IMG_8331Apparently I’m not the only one that have had problems with a Arduino nano’s USB connection. Usually it works ok but sometimes, particularly when an external power input is used, a FTDI chip inside the Arduino does not want to be detected by computer. This is bug made by the original Arduino developers, and can be easily fixed afterwards if there is odd troubles with it. Read More …

C64 XA1541 Cable

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 due lack of parallel port in modern computers.

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 …