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Felix Hoffmann, a German chemist, was searching for something to relieve his father's arthritis. In doing so, he "rediscovered" acetylsalicylic acid and in 1900, patented a stable process for developing it. Hence, we have aspirin.
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| Number | Title | Issue Date |
| 4324376 | Railroad highway crossing warning system A railroad highway crossing warning system including pickup coils for sensing current flowing in the track rails of an approach zone, a circuit for sensing the voltage across the track rails, band-pass filter circuits for filtering the voltage and current... | 04/13/1982 |
| 4325101 | Vital electronic time delay circuit A fail-safe electronic time delay circuit for providing a predetermined time delay period having an emitter-follower amplifier connectable to a source of recurrent signals, a voltage doubling rectifier for rectifying the amplified recurrent signals and fo... | 04/13/1982 |
| 4320315 | Fail-safe and gate circuit A fail-safe AND logic circuit including a free-running multivibrator and a pair of voltage reference networks. The multivibrator includes a pair of common emitter transistor amplifiers. The transistor amplifiers are separately biased and powered by an ind... | 03/16/1982 |
| 4320354 | Fail-safe band-pass circuit A vital narrow band-pass filter which operates in a fail-safe manner and includes a single stage input resonant circuit, an intermediate multistage parallel resonant circuit, and an output amplifying circuit for passing a given center carrier frequency si... | 03/16/1982 |
| 4315208 | Regulated power supply having its d.c. voltage source selectively supplemented by a d.c. to d.c. converter A transistorized power supply for providing a constant voltage to a load. A series regulator interposed between a d.c. input voltage source and the load to regulate the d.c. output voltage. A d.c. to d.c. converter serially connected between the d.c. inpu... | 02/09/1982 |
| 4314234 | Test set for railway cab signal system An electronic cab signal test set employing an integrated circuit code oscillator for producing a code signal and an integrated circuit carrier oscillator for producing a carrier signal which is modulated by the code signal to produce a code carrier signa... | 02/02/1982 |
| 4314237 | Fail-safe acknowledging circuit A fail-safe acknowledging circuit having a plurality of relay switching contacts having a predetermined order of more restrictive significance. A differentiating circuit selectively interconnected by certain ones of the plurality of relay switching contac... | 02/02/1982 |
| 4314306 | Signal-powered receiver A self-powered receiver including a series resonant circuit tuned to the carrier frequency of a modulated carrier signal. A demodulator for detecting the envelope which switches a switching transistor ON during the mark portions of the modulator carrier s... | 02/02/1982 |
| 4314374 | High power audio frequency transmitter A high power amplitude modulated audio frequency transmitter having a Twin-T low frequency oscillator, a tickler coil high frequency oscillator, a switching regulator and a switching amplifier. The Twin-T low frequency oscillator produces a sine wave modu... | 02/02/1982 |
| 4307860 | Railroad grade crossing constant warning protection system A train detection system for protecting a railroad highway crossing having an a.c. transmitter center-feeding voltage signals into the track rails and having a receiver including at least a pair of coils located on opposite sides of the crossing and dispo... | 12/29/1981 |
| 4306694 | Dual signal frequency motion monitor and broken rail detector A highway crossing warning system for monitoring the motion and predicting the time of arrival of an approaching train at the highway crossing and for detecting the presence of a broken rail in the approach zone by feeding dual frequency signals into the ... | 12/22/1981 |
| 4301490 | Electronic overload protection circuit A solid-state overload protection circuit for protecting a multiple-stage compound transistor power amplifier. The overload protection circuit includes a current-limiting circuit for sensing or limiting the current during an overload condition. The curren... | 11/17/1981 |
| 4297548 | Vital incidental movement monitoring arrangement A vital incidental relative movement monitor assembly including a support member and a carrier ring member which is screw-threaded into the support member. The carrier ring member includes an apertured annular flange which is concentric with an apertured ... | 10/27/1981 |
| 4296868 | Housing for draft gear In a draft gear apparatus, the housing is strengthened to better withstand distortion by draft stress imposed by the yoke on the end of the housing. Strengthening is accomplished by increasing the thickness of the housing side walls at selected areas near... | 10/27/1981 |
| 4288746 | Measuring sensor A speed measuring sensing device for producing a signal corresponding to the relative angular rotation between two structural members including a rotor arranged on the rotating member and a stator mounted on the stationary member. The stator is separated ... | 09/08/1981 |
| 4270810 | Circuit for influencing the brake-pressure release and/or brake-pressure holding phases for antilocking vehicle brake systems A circuit arrangement for influencing the brake pressure venting phase and/or brake pressure retaining phase for an antiskid vehicle braking system when the measured velocity difference deviates from a given velocity difference during controlled braking. ... | 06/02/1981 |
| 4125784 | Fail-safe or gate A fail-safe "OR" logic gate circuit which includes at least a first and a second level detector each of which has a voltage breakdown device and an oscillating circuit, a separate resonant tank circuit each of which is tuned to substantially the same freq... | 11/14/1978 |
| 4039920 | Cycling type of electronic battery charger This disclosure relates to a cycling type of a constant current electronically controlled battery charger having a reactive transformer, a full-wave rectifier, a series regulator and a sensing and control circuit for alternately supplying a low and high c... | 08/02/1977 |
