A simple low-power microscope

The simple illuminated monocular low-power microscope described here can be produced for much less than commercially available alternatives     

A simple scanning cytophotometer

Summary A simple, yet rapid and accurate apparatus for cytophotometry is described. It employs rapid scanning of an object field of 9 × 9 µ with a light spot of 0.8 µ in diameter. Light source variations are canceled through a two-beam arrangement. Silicon diodes are used as logarithmic elements and a sensitive galvanometer acts as an integrating measuring device.

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Zusammenfassung Es wird ein einfacher Zytophotometer für schnelle und präzise Messungen im sichtbaren Licht beschrieben. Ein mikroskopisches Feld (9 × 9 µ) wird von einem Leuchtpunkt (Durchmesser 0,8 µ) abgerastert. Helligkeitsschwankungen der Lichtquelle werden durch ein Zweistrahlverfahren kompensiert. Siliciumdioden finden Verwendung als logarithmische Schaltelemente und die integrierte Extinktion wird von einem empfindlichen Galvanometer direkt angezeigt.

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With 5 Figures in the Text     

A simple automatic dispensing apparatus

A simple dispenser using a 2-ml disposable syringe is described. The range of operation is 0.02–1.5 ml and an unusual accuracy is obtained by employing a new principle for dispensers: the dispensed volume is only a fraction of total tidal flow of fluid in the dispenser.     

A simple force platform.

The force platform consists of a sandwhich of steel, Rockwool and concrete plates about 900 X 700 mm in surface. Four steel rings were bolted to the under side of the steel plate in each corner. Each steel ring was furnished with only one strain gauge, two of which were placed on the outer- respectively on the inner side of each ring. The four strain gauges were connected to a measuring bridge. Before mounting the rings on the steel plate, the sensitivity to pressure of each ring was adjusted in such a way that they were all similar. Because of this the platform responded with a signal which was independent of where a pressure was applied within the surface of the platform. The platform showed a rectilinear response for static forces up to 500 kp with a stable zero value. In response to dynamic forces the platform showed a resononance frequency of about 50 Hz, with a damping factor of 0.15. Calibration of dynamic forces was carried out by calculation of the forces during a vertical jump compared with what would be expected from the time of flight also registered by the platform-measuring-bridge-ink-writer-set-up. The time of flight was significantly higher (11%) than exected from the time-force relations beforetake-off. This was esplained partly by the relatively low damping factor in the system, partly by the subjects not extending their knees at landing on the platform.