I created these displays for a vintage type project, but most folks who might build these will more than likely make use of modern driver electronics,such as Arduino, Pi etc.. My goal in this project log is simply to demonstrate the viability of using more modern familiar electronics to run the displays.
I just sent off a few PCB designs to OSH for driving these with TTL and microcontroller logic. Of course it's not all that complicated but want to provide some basic demos for those who may be unfamiliar with it.
This is pcb that will decode the display using diodes.
While I am waiting for them to come back I went ahead and made this prototype to make the display count from 0-4.
Here is the video of the count:
I didn't bother decoding all the numbers 0-9 as it is a waste of parts since the PCBS will be here in just over a week. The components used here are diodes to decode the display and form the numbers and a simple sequencer to run through them. I used some transistors to match the high voltage with the logic. Interesting enough they make several chips that perform all these functions in a 16 Pin dip package. The sequencer is all made from TTL chips, namely 74ls90 and 7442. The pulses originate from the old standby, a 555 timer..The pot is to speed or slow the count.
The power for this project is just a simple line supply, rectifying the 120VAC line to DC and using a small transformer to provide power for the digital chips via rectification,filtering and a simple 5 volt regulator.
Here is the finished module to decode the segments 0-9:
Lots of diodes!
This module is the driver It uses high voltage transistors:
Here is a video of the modules in operation:
A very big thanks to OSH Park for helping me with my project! Much of this would not have been possible without there help. They provided me with a coupon and it saved me. They are simply awesome.
And ideal situation would be for the driver module to be made with smt parts and built right into the back of the display. I can't make and solder things that small so things are pretty much how I will need to leave them for now. It works fine just a tad biggish. If anyone wants to take a crack at it feel free!
Will post more on this soon.