Amiga DB23 to SCART cable

I needed an Amiga DB23 to SCART cable. Searching online I’ve found this website Ian Stedman

Thank you Ian for the nice work!

I’ve tryed to follow he’s schematic but at first I don’t understand connection diagram because there is no reference of how pins are numbered. They are viewed from the front or from the back??? I’ve made a try and got it! Below you can see he’s original schematic plus my reference addon.

And this is the final result on a LED tv

5V to 900V step-up converter module


This project response to my need of an universal high voltage power supply to be used with mostly all type of geiger tubes that I have in my collection.

I’ve needed a selectable output voltage between 300V and 900-1000V, low power output, on board pulse counter and maybe a display. All powered by 5V


I’ve started the design of this voltage converter scrapping my “Madexp PMT adapter” power supply section. For more info visit
In that old project I’ve generated 900-1600V out with a single 5V source from USB via a simple TTL variable duty cycle oscillator.
I’ve replaced that oscillator with an Atmega328P MCU so I was capable to add programmable voltage output via 4 bit parallel interface, pulse counting and if I need, an 0.96″ OLED display.
Into this schematic there is a missing 100pF capacitor from pin INT0 to ground. The oled display have also two 1K pull up resistors on I2C lines
On the first prototype I’ve easily reached 1650V of output but into the second (current) production prototype I could not exced 900V because of the insufficent spacing between HV multiplier and the MCU. This is not an issue because  mostly all geiger tubes works with less than 900V.
The board is thinked to be used as a module of a bigger project or stand alone.
As module of a bigger project, you can simply omit the OLED display and connect the 8 pin connetor to your project. The 4 bit parallel interface selects voltage output and the ACK pin goes HIGH when the output voltage selected is reached/stabilized.
If you wish to use the module as stand alone, you can connect the OLED and a geiger on the + and OUT pins, 5V supply from a battery (voltage regulator NOT included) and you can see the voltage, pulses per minute (CPM) and last minute reading on the display. The output voltage is selected by make a soldering bridge on voltage selection jumpers. It permit you to made a pocket size geiger counter with very low effort.
If you wish to made a geiger clicker without display you cold simply connect a little speaker between pin 1 of the 8 pin connector marked as “^” and GND, omit OLED.
The 3 pin output connector have a geiger katode connection marked as “OUT” and also permit you to exclude the pulse counting and conditioning section connecting the powered item directly between HV and GND.

There is also a JTAG connector for uploading new firmware via a USBAsp programmer. During operation the jtag pins 3 and 4 becomes RX/TX uart. Pin 1 is GND.

The voltage selection jumpers are made to select output voltage when the board is used stand-alone. Make a solder bridge according with the table below and you’ll get the corresponding output voltage out.


The firmware is in currently developement but it’s already stable, counts pulses, display voltage and also send info like pulses/voltage via UART.


This project was published on Kickstarter and was active for pledges during all the month of September. I’ve realy appreciated the 30 pledges (one was for two boards) received, that made me capable of buy all the tooling needed to build the boards and further inprove their design.

At the moment the boards are travelling around the globe to reach their owners. I’ve send most of them to USA and Australia but also to Japan, Germany, Switzerland, Canada, Spain, Russia, Ireland and UK. I’m very happy about this result. This make me feel like a multi national corporate, it stimulate my hungry for new projects. Thank you again and stay tuned, you’ll see some new crazy project soon!


Here you cand download the board manual complete with schematic MadexpHV manual 0.3


Experimenting with home made computers usually results into the use of a pletora of discrete TTL IC in order, for example, to make the I/O address decode. For this reason I’ve started using GAL gate array logic IC’S.

This type of IC are programmable by a PC software and can substitute a complex logic network made of several TTL’s into a single package. For more info about GAL theory

One of the cheapest and easiest GAL to find to buy online is the Lattice GAL16V8.

This is IC works with only 5V supply, is TTL compatible and it’s speed usually is within 250Mhz!

It have 8 only input pins (2-9), one input/clock input pin (1), one input/~output enable pin (11) and 8 input/output pins (12-19).

To program this chip you need to write the description of the logic network that must be synthetized into it and compile the code. WinCUPL is a Windows software that have an editor, compiler and simulator.


This software is free to use and download from Microchip’s website. At this link you can find the download page with the software and manual. For my personal archive I’ve added it wincupl. This zip contains the software, license and documentation.

The code inputed into the software must be compiled and the resulting .jed file burned into the IC with an universal burner like Willem USB programmer. The file could be also simulated with the included simulator.

Included into WinCUPL installation directory there are several examples. You can learn quick the CUPL language following the examples.

You could generate the CUPL code file with the old PROTEL 99SE software, drawing directly the schematic, then compiling it with WinCUPL software.

BW radiation dosimeter, tactical, set 0065 B

Bundeswehr radiation dosimeter, tactical, set 0065 B


For about 25€ I’ve find this nice militar dosimeter set. It comes from german army and it’s a nice take for the money, the box is made with wood and is methal reinforced. It’s small in size and not too much heavy. It’s looks extremly well made and solid. I’ve bought it on eBay from a military surplus seller; this item is very easy to find searching for “BW Strahlendosimeter, taktisch, Satz 0065 B”

The box


How it looks inside

Inside the box there is a yellow plastic charger with a light bulb that is used to read/reset to zero the dosimeter, 6 high rate dosimeters and 6 lower rate dosimeters.

This type of dosimeters are “quartz fiber dosimeter”, here you can find more info Wikipedia

The dosimeter’s assembly

The label

The lower rate dosimeters have the range 0/50 roetgens, the high rate 0/600 roetgens.

Here is what you could see into such dosimeters. The sensibility of such devices is soo low that you hardly will see a move of the line along de scale except when the internal capacitor is discharged by self losses and need to be re-zeroed by the charger.