A transistor-oscillator limit switch for indicating and recording instruments
J. T. Wintermute, S. G. Hayter · Transactions of the American Institute of Electrical Engineers Part I Communication and Electronics · 1960
The continued development of automatic controls has emphasized the need for limit switches on indicating and recording instruments which will not restrict the normal operation of the measuring unit. This control has been obtained in the past in two ways: 1. By contacts carried on the instrument pointer. 2. By employing a vane attached to the pointer to change the constants of a vacuumtube oscillator circuit, and using the change in oscillator current to operate a relay.