Jaap's Mechanical Calculators Page

Schildkröt Minirechner 99

Schildkrot Minirechner 99


Schildkröt Minirechner 99
History
Patents
Links


Schildkröt Minirechner 99

The Minirechner 99 is a sophisticated toy adding machine made by Schildkröt in 1971. It has a dial like a rotary phone which has 10 finger holes numbered 1 to 10. On the left are two small windows showing the 2-digit register. Below that are two larger windows that cleverly display the register amount using coloured dots. There is a slider that can cover the digit window, leaving only the dots visible. When you dial clockwise any number from 1 to 10, it gets added to the register.

There is a selection switch above the dial. If you move that switch to subtraction, the number labels on the dial reverse their order and turn red. To subtract a number you need to dial it anti-clockwise. The register cannot go below zero. The selection switch also has multiplication and division settings, and in those modes a number wheel to the right of the dial is used as a counter register. To multiply, reset everything to zero and then simply repeatedly dial one of the factors until the counter register displays the other factor.

Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99

It came with the original cardboard box.

Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99

I do not have an instruction booklet, but the box has brief instructions printed on the sides in German and French. There is some tape damage, I had to guess at some of the missing words. It is reproduced below, together with my English translation.

+
Zusammenzählen = Knopf über der Wählscheibe auf +
0 in allen Fenstern einstellen.
Zahlen der Rechenaufgabe mit der Wahlscheibe bis zum Anschlag nach rechts drehen.
Ergebnis: linke Fenster

×
Malnehmen = Knopf ü der Wählscheibe auf ×
0 in allen Fenster.
Roten Zeiger mit dem Schieber auf eine Zahl (8) der Rechenaufgabe stellen die unter 10 liegt.
Diese Zahl (8) so oft bis zum Anschlag nach rechts drehen, bis im rechten Fenster die malzunehmen Zahl (2) erscheint.
Ergebnis: linke Fenster

-
Abziehen = Knopf über der Wählscheibe auf -
Die größere Zahl mit dem Rädchen in den linken Fenstern einstellen.
Die abzuziehende Zahl mit der Wählscheibe nach links drehen.
Ergebnis: linke Fenster

:
Teilen = Knopf über der Wählscheibe auf :
Rechtes Fenster auf 0.
Größere Zahl (16) der Rechenaufgabe mit den Rädchen in den linken Fenstern einstellen.
Roten Zeiger mit dem Schieber auf die kleinere Zahl (8) stellen durch die geteilt wird.
Diese Zahl (8) wird so oft bis zum Anschlag nach links gedreht, bis in den linken Fenstern 0 erscheint.
Ergebnis: rechtes Fenster (2)

+
Additioner = Placer le bouton au-dessus du cadran sur le signe +
Composer à l'aide de celui-ci les opérations à effectuer en tournant le disque vers la droite jusqu'à son arrêt.
Le résultat sera lisible dans les fenêtres de gauche.

×
Multiplier = Placer le bouton au-dessus du cadran sur le signe ×
0 dans toutes les fenêtres.
Positionner l'indicateur rouge avec le curseur sur un chiffre (8 p.ex.) de l'opération à effectuer. Ce chiffre doit toujours être inférieur à 10.
Le chiffre (8 p.ex.) doit être repris autant de fois sur le cadran, dans le sens des aiguilles de montre, jusqu'à ce qu'apparaisse dans la fenêtre de droite le multiplicateur (2 p.ex.). Effectuez la manoeuvre en tournant jusqu'à la butée.
Le résultat sera lisible dans les fenêtres de gauche.

-
Soustraire = Placer le bouton au-dessus du cadran sur le signe -
Positionner dans les fenêtres de gauche à l'aide des petites roues le chiffre le plus élevé.
Choisir le chiffre à soustraire sure le cadran et tourner celui-ci vers la gauche.
Le résultat sera lisible dans les fenêtres de gauche.

:
Diviser = Placer le bouton au-dessus du cadran sur le signe :
Placer la somme à diviser (16 p.ex.) à l'aide des petites roues dans les fenêtres de gauche.
Positionner l'indicateur rouge avec le curseur sur le diviseur (8 p.ex.).
Le diviseur, en l'occurance est tourné autant de fois à gauche, jusqu'à ce que zero apparaisse dans les fenêtres de gauche. Effectuez le cadran en tournant jusqu'à la butée.
Le résultat sera lisible dans la fenêtrede droite (2 p.ex.).

+
Addition = Set switch above the dial to +
Set 0 in all windows.
Enter the numbers of the sum using the dial, turning it to the right until the stop.
Result: left windows

×
Multiplication = Set switch above the dial to ×
Set 0 in all windows.
Set the red pointer inside the dial to one of the numbers (e.g. 8) in the problem. This number must be at most 10.
The number (e.g., 8) must be dialled clockwise until the stop as many times as necessary until the multiplier (e.g., 2) appears in the right-hand window.
Result: left windows

-
Subtraction = Set switch above the dial to -
Set the register in the left windows to the largest number by turning its gear wheels.
Subtract the other number by dialling it anti-clockwise until the stop.
Result: left windows

:
Division = Set switch above the dial to :
Set 0 in right window.
Set the register in the left windows to the largest number (e.g. 16) by turning its gear wheels.
Set the red pointer inside the dial to the other number (e.g. 8) in the problem, the divisor.
The number (e.g. 8) must be dialled anti-clockwise until the stop as many times as necessary until the left window shows zero.
Result: right window (e.g. 2)


The casing of the Minirechner is glued together. I was not able to open it completely, but managed to separate part of the case to give a glimpse of the mechanism and give enough access for some lubrication.

Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99
Schildkrot Minirechner 99

History

tomthumblogo Schildkröt-Puppen und Spielwaren GmbH is a toy company based in Rauenstein, Thüringen. It was founded in 1873 as "Rheinische Hartgummi-Waaren-Fabrik", but with the introduction of celluloid in 1885 it becamse Rheinische Gummi- und Celluloidfabrik. They made various rubber and celluloid items, from handles for umbrellas and canes, to table tennis balls. They first started making dolls in 1896 and still do so today, which now makes them the oldest dollmaking company in the world. They became famous for their dolls, because making them from celluloid instead of porcelain allowed them to be safer for children and to be produced on a much larger scale.

The Minirechner 99 was invented by Karola Thevis (née Eigelshoven) of Oberndorf, Germany. This information is from the patents, and I have not been able to find out anything else about her.


Patents

There are three German patents, which were mostly combined together for the foreign patent,

PatentFiling datePriority dateNameDescription
DE 1,772,89617-07-196823-12-1970Schildkröt AG; Karola ThevisLernrechenmaschine
DE 1,803,13416-10-196801-10-1970Schildkröt AG; Karola ThevisLernrechenmaschine
DE 2,031,15124-06-197027-01-1972Schildkröt AG; Karola ThevisLernrechenmaschine
US 3,645,44015-07-196929-02-1972Schildkröt AG; Karola ThevisCalculating machine
See also: AT 307,090 CH 517,982 FR 2,013,119 GB 1,274,037 SE 355,885

Links

I have not found any trace of this adding machine on the internet, so the only links here are about the Schildkröt company itself.


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