by the printer and a check can be carried out directly after the adjustment to see whether individual prints on the sheets do or do not smear at the sheet guide means 43 when used in conjunction with the bowden cable construction the reference strip 15 and the led display 23 is particularly important and greatly simplifies the adjustment of the sheet guide 43 for the printer turning now to fig4 there is shown a detailed view of the sensor and indicator circuits the bar 42 is a magnet and the sensors 24 39 are current sourcing unipolar digital hall effect sensors such as part number 613ss2 manufactured and sold by micro switch a honeywell division 11 w spring st freeport ill 61032 these devices are actuated by a magnetic field of 560 gauss or less and release when the magnetic field drops at least to 185 gauss for a temperature range of 0 u00b0 to 70 u00b0 centigrade the hall effect element is a tiny integrated circuit within a plastic package that is only 0 21 inches square plus terminals this particular part number requires a supply voltage of 6 to 16 volts and thus can be supplied by a standard 12 volt power supply without worry of variation in supply voltage when these devices are activated they provide a 1 5 volt output signal sourcing up to 10 milliamperes the integrated circuit packages have four output.