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Wecome To The New Home Of TheEPROM9
First job was to reverse engineer the display so I knew the pin out. this was done by hooking an fluorescent light electronic ballast for a cold cathode tube to random pins.
I also made a chart of Soviet chars the display could cycle though randomly. Some chars were just impossible to display just like on any 7-seg display.
So a side from popping a few driver boards for the HV. I wanted to use relays to drive the HV its self & an Arduino to drive the relays. Why relays, first the make a nice clicking noise & second complete isolation between the HV side & the Arduino, plus finding transistors that can take the KV range AC, not your normal jelly bean ones.
So first I had the Arduino driving the relays directly, however the EMF back feeding from the coils kept crashing it. I then added an array of transistors, the Arduino was reliable at the back EMF was not a problem for the 2N3904 transistors, so I was able to delete having diodes for protection. A very Sinclair move. Then I needed add the caps in series with each segment or all the segments would be really dim. Was all to do with current usage of the segments.
The display running though the segment test sequence.
The display showing one of the Soviet char's.
The YouTube video gives a nice overview of how the device works & the different parts that make it up.
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