I have a very special original historical circuit diagram dating back to the 1950's. Now what is so special about this diagram. This circuit diagram has the following characteristics:
- This diagram is the original diagram that was included with the product purchased from Italy.
- This diagram was hand drawn. ( A real work of art!)
- The ink used was not normal ball-point type ink. It might have been drawn with a type of fountain pen or an even earlier dipped ink pen.
- This circuit diagram was not drawn on ordinary paper. The type of paper has the characteristics of a material based paper that was used to draw patents on in the 1950's.
- Durability and quality was clearly part and parcel of the product that was sold by the manufacturing company.
- The condition of the drawing is still fairly good which is quite remarkable for a piece of "paper" dating back to the 1950's. If normal paper was used this diagram would have been the worst for wear as this specific diagram was used many times since the purchase date.
To try and preserve this historical circuit diagram I have decided to laminate it as the diagram was folded in two places and from old age it started to tear in one area. The tearing was a blessing in disguise as this revealed the structure of the paper to be material based. The lamination clearly was the answer to prevent further deterioration of this historical diagram.
What diagram is being drawn on this material based paper?
The circuit diagram is related to a VFO exciter unit N 4/102/K product manufactured by Geloso in Italy in the 1950's.
Image (Click on image for larger view)
Herewith more information on the history of the Geloso company.
The Geloso Signal Shifter (PDF)
Images (Click on images for larger view.
