Abstract: A device is disclosed for generating a rotatable magnetic field for calibing a compass. The field generated overcomes the earth's magnetic field and any other nearby magnetic field. A U-shaped housing has a first calibrated dial on the top horizontal member and a dial on the bottom horizontal member. The dials are mechanically linked to rotate in unison. Each dial contains a pair of bar magnets. The compass to be tested is positioned within the interior of the U-shaped housing. An adjustment knob is provided for turning the top and bottom dials and thereby permitting orientation of the four magnets within a range of 360.degree.. The accuracy of the compass can thereby be tested.

Abstract: In a device for graphically representing characters encoded in a digital nal, a writing element adapted to sweep across a recording medium at selected intervals is enabled by a timing means to selectively mark the recording medium during a selected series of sweeps, and a decoding means receives the digital signal and provides segment select signals, which specify a combination of segments from a group of segments which may graphically represent each of the characters in the digital signal. The outputs of the timing means and the decoding means are coupled to a network of logic elements to generate a signal which is coupled to the writing element, whereby the writing element selectively marks the recording medium during the series of sweeps to form the segments representing each of the characters.

Abstract: An apparatus for filling or bleeding fluid out of a container which is cld by a plug wherein the apparatus includes a block which has a cavity. A gasket and a clamp are utilized for sealably attaching the block to the container so that the cavity can be sealed about the plug. The block has a pair of passageways which extend outwardly from the cavity to respective spaced apart ports. A fitting is connected in the port of one of the passageways for filling or bleeding fluid through the plug opening, and a screwdriver is slidably fitted through the other passageway for loosening or tightening the plug in the plug opening. The screwdriver may be sealed to its respective passageway by an O-ring when the screwdriver is inserted therethrough. In this manner, a seal of the container is maintained while (1) the plug is loosened, (2) while fluid is inserted in or bled from the container, and (3) while the plug is tightened in the plug opening.