Abstract: The invention includes a direct current energy source monitor which automatically detects the nominal voltage of the direct current energy source to which it is attached. The invention further includes a direct current energy source monitor which is self-powered from the direct current energy source being monitored. The multiple nominal voltage direct current energy source monitor includes an analog-to-digital converter configured to measure voltage from a direct current energy source being monitored and generate a digital output corresponding thereto. The apparatus includes a programmable control device configured to receive the digital output from the analog-to-digital converter and to look up a nominal voltage corresponding to the digital output, and is further configured to calculate a relative charge of the direct current energy source as compared to a full charge on the direct current energy source.

Abstract: An event counter is disclosed which, in one embodiment, provides a reaction timer to time a user's response time to an event. In a second embodiment, the event counter provides a counting device to count the number of occurrences of events or the magnitude of an event. The invention uses a commercially available stopwatch to time the response time. The start/stop switch of the stopwatch is connected to a signal generator such as a piezoelectric element. In one variation, the internal piezoelectric element used as a beeper in the stopwatch is used as the signal generator. In a second variation, the event timer is further provided with a circuit to allow a higher voltage LED to be driven by a lower voltage of the system battery. In yet another variation, the event timer further includes a random delay circuit to randomly delay the start time of the stopwatch. Random delay is provided without a microprocessor by using a variable current switch and two RC circuits having different tau values.

Abstract: The present invention discloses a circuit for providing a variable output signal in response to a physical parameter sensed by a sensor in the circuit, preferably a force sensing resistor. The current mirror may consist of two transistors having common bases. Flow of current through the first transistor flows through the sensor and through a parallel resistor. This current is mirrored in a second transistor which provides flow of current which may either be used as an output signal or, more preferably, as a base current for a transistor which is used to control output signal voltage. The circuit uses the current mirror in connection with the sensor to eliminate the need for a negative voltage supply. The circuit may further advantageously contain a voltage limiter module which is used to limit the voltage which may be applied across the sensor if the range of input signals or the desired range of output signals exceeds the sensor's capability.