Barbouri's Electronics Projects
Restoring vintage electronics along with designing and building new circuits. One eye looking into the past, the other looking into the future.
I again wasn’t looking to start another calculator project when this Burroughs C5155 calculator showed up in one of my automated searches. The price including shipping was a bargain, so I purchased it.
I managed to snag a Monroe 430 calculator that was in good condition and a reasonable price. The Monroe 430 is 14 digit four-function calculator with memory, percent, and a few other extras. I have worked on a model 425 and 420 in the past so I kind of knew what I was getting into, especially the lack of documentation.
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.
Another bargain price purchase of an Eico Unitrex 1200M calculator. This model also uses the same CT5005 LSI calculator on a chip IC as the APF Mark XII Calculator, but is noteworthy because of the relationship of Eico with Cal-Tex Semiconductor, Inc., the manufacture of the IC chip. The 1200M was the first calculator to use a single LSI IC with integrated memory. It also has a beautiful 12 digit Neon gas-discharge display.
A recent addition to the desktop calculator collection is the Canon Canola L100A desktop 10 digit gas discharge display calculator. This unit was purchased as a working calculator, and was in good shape except the heavy yellowing of the beige upper case..
Adding a new HP 34700 series module to the collection. This time it is the 34721B BCD interface plug-between module, which converts character serial data from the 34740A or 34750A Display Module to parallel character information for output to a printer.
Checking out a HP 3551A sold as “For parts or not working, will not power on”, that I actually purchased for parts.
My original intent on purchasing this unit was to salvage the knobs and connectors for repairing some of my other HP gear. I did manage to swap out four of the knobs before my curiosity got the better of me.
Cleanup and repair of a Hewlett Packard (HP) 8012B pulse generator purchased on Ebay as “Untested does not power on, sold as is”.
The 8012B was originally produced by the HP Gmbh Boeblingen Divison, Germany, but this later model was made in USA. It provides variable transition times down to 5 ns and the repetition rate can be adjusted from 1 Hz to 50 MHz.
When I purchased my HP 34750A Display module, it came with a somewhat beat-up 34702A Multimeter module. I was mainly interested in the display module to pair up with my existing HP 34703A module, but this is also an interesting module worthy of further exploration.
Continue reading “Hewlett Packard 34702A Multimeter Module”A very interesting find on Ebay from several years ago was an all steel version of a J.H.W. CLIMAX Co padlock.
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Cleanup and check of a Mettler Instruments K4T single pan top loading balance.
After owning and using this K4T balance for over twelve years, I thought it was time for a full cleanup and accuracy check. When first purchased from Ebay it received a quick cleanup, function, and accuracy check, before I quickly put it to use.
Continue reading “Mettler K4T Balance”
Building a 10 volt reference using some vintage AD584 IC’s from 1983.