Abstract: An electronic level having a horizontal and/or a vertical transducer, each of which exhibits an effective impedance that is a function of the deviation of that transducer from a reference plane. Preferably, each transducer is an electrolytic transducer formed of a container partially filled with electrolytic liquid. Depending upon the general horizontal or vertical orientation of the level, one or the other transducer is connected to a drive signal generating circuit which supplies an output drive signal of a magnitude that is a function of the impedance of that transducer. This output drive signal is applied to a display driver which, in turn, drives an array of visual indicators in accordance with the output signal magnitude.

Abstract: A retractable tape measure having a casing which contains a coiled tape rule whose free end extends through an opening in the casing and includes means for locking the tape against automatic retraction into the casing. The lock means consists of a locking member mounted in the casing for pivotal movement in a plane generally transverse to the direction of retraction of the tape, with a free end located to engage the tape and hold it against a portion of the casing in a first pivoted position of the lock member and to be spaced from the tape in a second pivoted position. A slide actuator operatively engaged through a cam arrangement is provided for pivoting the lock member between its first and second positions.

Abstract: An illuminated retractable tape measure has a casing which contains a coiled tape rule whose free end extends through an opening in the casing. A lock arrangement locks the tape against automatic retraction into the casing. In the lock arrangement, a locking member is mounted in the casing with an end thereof engageable with the tape to hold the same against a portion of the casing in a locking position. The end of the locking member is moved out of engagement with the tape when an unlocked position is established. A slide actuator pivots the lock member between its locked and unlocked positions. A small lamp or lamps is incorporated in the casing for illuminating the ruling on the tape measure, and the actuator closes a switch when the actuator is moved to its locked position to light the lamp. This feature facilitates reading measurements on the tape measure, especially in adverse lighting conditions.