Power Cords for Mechanical Calculators

[hea...@gmail.com]

I have 3 mechanical calculators: Friden, Marchant, Monroe. Massive things.

I never thought of buying one, so I have only a vague idea of their original price.
About $1000 in the 50s. The ones that could do square roots were more. They
were soon out-done by electronic hand-helds in the $100 range and soon
thereafter in the $30 range.  Cheaper dollars, as well.

I noticed montages at art fairs, filled with lovely gears, and it occurred to me that
these beautiful machines were being cannibalized for art, and that I was duty-bound
to preserve a few.

So: 3 calculators, but a power cord only for the Monroe -- so ragged, I'm afraid to use it.
I describe it below.

The power connection at the Monroe is male; the calculator end of the power cord
is female. Instead of the blade connectors, there are circular rods. Approximate
measurements: Rod Diameter: 0.15 in; Distance Between Rods: 0.17 in. I would
probably have to carve the rubber portion to fit the opening in the calculator.

The Friden connection has 3 round rods.
The Marchant has 2 round rods, more separated than the Monroe's.

Now the project: Buy the exact power cord or build one. I don't think the first option
is feasible.

In an early scene in the movie, The Apartment, we see a seemingly unlimited farm
of desks, Jack Lemon's among them, in an infinite room. Each desk is armed with
one of these calculators.

Any ideas?

[Andrea Celli]

Hi,
all original cords i have aren't affordable.
Rubber is in ill conditions and doesn't warrant insulation.

May be on US flea markets you can find original female ends.
This would enable to build a new cord.

Here, in Italy, i used a standard PC power cable,
with a standard American female end.
First i "rounded" the three holes. It's enough to push a large nail in them.
Not too deep.
Then i "rounded" external shape of the outlet. A good knife is ok.

Andrea

2013/5/29 <hea...@gmail.com>:

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[hea...@gmail.com]

[Harry Ward]

Andrea,

Thanks, This solution may work for 1 or 2 of my 3 calculators.

Harry

--

[Andrea Celli]

I forgot, plugs in some eBay auctions (e.g #200928996715,
330930454752, ...) are suitable for Walther EMKD and few other
European electric calculators.

I will try to explain myself. In Italy we use two plugs:
- domestic, with 2 or 3 small and near holes
- industrial, with 3 largest and more distant holes

In old plugs used for (ironing) irons, ..., calculators we had just 2
large but near holes. In "modern" version a ground contact has been
added on sides to make them saver.

andrea

2013/5/30 Harry Ward <hea...@gmail.com>:

[Mike Hatch]

Hi,

Can you take a photo of the power connectors and upload it somewhere ?,
then we can see what you are looking for.

Mike.
mi...@soemtron.org
www.soemtron.org
www.pdp-7.org

[mg]

The Marchant cords are similar to old percolator coffee maker plugs - you can often find those at thrift stores.  The Friden cords were also used by Victor (who sold a lot more machines than Friden) and early HP test equipment.  Monroe cords are the tricky one - they were only used by Monroe (as far as I know) and they were made of a material that has not survived well over the years.  I think that Facit must have used the same material for their power cords.  One of the projects on my list is to make some replacement power cord receptacles using the 3-D printer we have here at work, but given the rate at which things on the list get done, this may take a long while.

I may have a spare Friden and maybe even a Marchant cord - send me an e-mail directly.  For the Monroe, all I can suggest is splicing the old receptacle onto a new cord.

--

Mark

On Wednesday, May 29, 2013 12:15:30 PM UTC-7, hea...@gmail.com wrote:

I have 3 mechanical calculators: Friden, Marchant, Monroe. Massive things.

[Harry Ward]

Attached is a scanned copy of the Monroe connector.
Tomorrow I'll send a photo, and photos of the calculator connectors.

[Harry Ward]

Attached are:

Photos of Connectors for:

Friden

Marchant

Monroe

Text Description of the three.

--

[Harry Ward]

MG,

Thanks. I was given an old Farberware percolater to try. It's a great fit, but I haven't tried it yet. I worry about polarity and wattage. It doesn't look to have the capacity of say a PC power cord or of the badly-worn Monroe cord.

Harry

[Norm Goldblatt]

Yes, even with AC, it makes a difference on old machines.  I have a Marchant. If the plug is in the 'wrong' way, I get a little tingling when I touch metal parts.  Best to take a voltmeter and go between the chassis and true ground (say, the middle prong on the outlet. There should not be any AC voltage there. If there is, switch either the plug end or the socket end of the cord and try again.  It won't hurt the machine.  Lots of old electronics behave this way.  Sometimes they trip my GFI.  Percolators carry a huge current, so I wouldn't worry about the heft of the wire.

Norm

Visit this group at http://groups.google.com/group/oldcalculatorforum.

[hea...@gmail.com]

On Wednesday, May 29, 2013 2:15:30 PM UTC-5, hea...@gmail.com wrote:

[hea...@gmail.com]

Norm,

Thanks. I'll find my voltmeter.

Harry

On Wednesday, May 29, 2013 2:15:30 PM UTC-5, hea...@gmail.com wrote: