RICHARD CAMPBELL
Cosmetology in Pittsburgh, PA

4320881, Mar 23, 1982

Oct 3, 1980

6/193765

Richard D. Campbell - Swissvale PA

American Standard Inc. - Swissvale PA

B61L 2100, G08C 1928

246 34B

A selected unique digital comma-free code word is transmitted through track section rails from one end and, when received at the other end, is applied serially to a shift register which supplies a parallel readout of shifting pattern to one input of a fail-safe comparator. The second comparator input is selected from the different possible digital code patterns of the track code word stored in a memory device. When inputs are equivalent, the comparator passes an input test signal to its output. Absence of comparator output causes the selected stored code word to be stepped through the stored patterns, in reverse order to track code shift, until equivalence is again obtained. The periodic output signals, of approximately 50% duty cycle, are processed through a series filter-rectifier network, tuned to test and periodic output signal frequencies, to energize a track relay to register an unoccupied track section indication.

4328541, May 4, 1982

May 23, 1980

6/152884

Richard D. Campbell - Swissvale PA

American Standard Inc. - Swissvale PA

G06F 704

3401462

A digital comparator with a comparison cell for each pair of digits of two words stored in separate register banks. Each corresponding pair of register stages is coupled to the associated comparator cell by a rectifier interface network which supplies an actuating signal only when the associated word digits have complementary characteristics. The comparator cells are coupled in series and interfaced to input and output by optical coupler units. Each cell includes an LC network tuned to the selected frequency of an input test signal which is passed through the comparator chain, from highest to lowest order cells, only if each cell is actuated by an input signal from the associated interface network, thus indicating that each pair of word digits is complementary.

4661722, Apr 28, 1987

Sep 17, 1984

6/651731

Richard D. Campbell - Swissvale PA

American Standard Inc. - North Hills PA

H02M 510

307419

A fail-safe electronic coincidence detecting circuit including a multiple winding saturable core reactor having a first and a second input winding and an output winding. An NPN transistor amplifier supplying a first pulse train to the first input winding and a PNP transistor amplifier supplying a second pulse train to the second input winding. The output winding producing signal pulses only when the first and second pulse trains are in synchronism.

4306695, Dec 22, 1981

Jul 9, 1979

6/055590

Richard D. Campbell - Swissvale PA

American Standard Inc. - Swissvale PA

B61L 2502, H03H 1112

246182BH

A non-linear filter which reduces high signal-to-noise ratio due to sharp and erratic variations in an input signal by charging a storage capacitor through a long time constant charging circuit so that the stored signal level lags an increasing input. A parallel path with a much lower time constant rapidly discharges the capacitor upon input decreases, so that the stored signal matches the more accurate lower input signal level. A practical application is for car space measurements in railroad yard storage tracks to substantially reduce erratic distance measurements due to poor shunting under moving cars. The distance measurement signal is applied through an integrator network to a first of four FET operational amplifiers, whose input and feedback networks have selected time constants to substantially filter out background noise due to the track signal frequency. The second amplifier provides a perfect rectifier for the discharge of the storage capacitor through a low time constant path when the input signal decreases. A T-shaped resistor network and the third amplifier provide longer time constants to delay the charging of the storage capacitor, in accordance with an increasing output level from the first amplifier, without requiring excessively large component values.