Monroe 650 Calculator repair and cleanup

Welp, anoth­er cal­cu­la­tor tale of woe. This time it is a Monroe 650 cal­cu­la­tor found on eBay. The 650 is the top-end mod­el of Monroe’s 600 series cal­cu­la­tors. It is a 16 dig­it Nixie tube dis­play cal­cu­la­tor with addi­tion, sub­trac­tion, mul­ti­pli­ca­tion, divi­sion, square root func­tion, and two mem­o­ries. It oper­ates in fixed dec­i­mal or float­ing point modes, and has 5 chang­ing indi­ca­tors spaced every incre­ment of the base-10 expo­nent of three from the dec­i­mal point.
The price was right and includ­ed free shipping.

Monroe 650 cal­cu­la­tor after cleanup and repairs
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Updated IceTube Clock Design

After fin­ish­ing the IceTube clock ver­sion 1.31 build for myself, I was ready to work on the board design for some IceTube clocks as gifts. I could have used the exist­ing V 1.31 boards, but I want­ed to use an up to date design that incor­po­rat­ed all the hard­ware improve­ments over the past 10 years while still stay­ing with a thru-hole design.

IceTube clock Version 2.1 mount­ed in laser cut acrylic enclo­sure. March 2020
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