Abstract: An approach is that uses a first amount of energy used by a motor to open a vent and reducing the amount of energy to a second amount of energy to maintain the vent in an open position.

Abstract: A method for determining a height of a sash opening formed by a movable sash in a fume hood. The method includes providing a laser device on the hood and providing a reflector on the sash. In addition, the method includes positioning the sash in an open position to form the sash opening and measuring a first distance between the laser device and the reflector when the sash is in the open position. The method also includes calculating the sash height based on the first distance.

Abstract: Motor control systems and methods. A motor control system includes a temperature compensated power supply configured to receive a supply voltage and output a temperature compensated reference voltage. The reference voltage varies according to an ambient temperature of the motor control system. The motor control system includes a microcontroller configured to receive the temperature compensated reference voltage and a sensed motor current and to produce a corresponding pulse-width-modulated (PWM) motor control signal. The microcontroller is configured to increase a duty cycle of the PWM motor control signal as a function of the temperature compensated reference voltage. The motor control system includes a motor configured to be controlled according to the duty cycle of the motor control signal.

Abstract: An approach is that uses a first amount of energy used by a motor to open a vent and reducing the amount of energy to a second amount of energy to maintain the vent in an open position.

Abstract: An apparatus is provided that increases resolution of a resistance sensor. The apparatus may include a variable current source that produces a variable current in response to a current value. The apparatus may also include a variable resistance device that generates a variable voltage associated with the variable current. The variable resistance may have a low resistance value and a high resistance value. In addition, the apparatus may include a controller that receives a voltage value associated with the variable voltage and controls the current value in order to result in an increase in resolution of a range between the low resistance value and a high resistance value.

Abstract: A method for determining a height of a sash opening formed by a movable sash in a fume hood. The method includes providing a laser device on the hood and providing a reflector on the sash. In addition, the method includes positioning the sash in an open position to form the sash opening and measuring a first distance between the laser device and the reflector when the sash is in the open position. The method also includes calculating the sash height based on the first distance.

Abstract: A system for determining a sash panel position. An example system includes a linear array of light emitting elements spaced at equal distances from one another mounted on a fume hood frame. The light emitting elements generate a light path towards a sash panel such that the sash panel blocks the light path when positioned at the light emitting element. A linear array of light sensing elements is spaced at equal distances from one another on a side opposite the sash panel. The light sensing elements receive the light path generated by corresponding light emitting elements when the sash panel does not block the light path. The light sensing elements may be on modules having shift registers with bits corresponding to the light sensing elements. The shift register stores a state of the light sensing element and outputs a series of bits indicating the state of each light sensing element.

Abstract: A method for determining a height of a sash opening formed by a movable sash in a fume hood. The method includes providing a laser device on the hood and providing a reflector on the sash. In addition, the method includes positioning the sash in an open position to form the sash opening and measuring a first distance between the laser device and the reflector when the sash is in the open position. The method also includes calculating the sash height based on the first distance.

Abstract: An approach for maximizing the resolution of a resistance sensor with a variable current source.

Abstract: Increasing the resolution of a resistance sensor by adjusting a current source.

Abstract: An approach for maximizing the resolution of a resistance sensor with a variable current source.

Abstract: A system for determining a sash panel position. An example system includes a linear array of light emitting elements spaced at equal distances from one another mounted on a fume hood frame. The light emitting elements generate a light path towards a sash panel such that the sash panel blocks the light path when positioned at the light emitting element. A linear array of light sensing elements is spaced at equal distances from one another on a side opposite the sash panel. The light sensing elements receive the light path generated by corresponding light emitting elements when the sash panel does not block the light path. The light sensing elements may be on modules having shift registers with bits corresponding to the light sensing elements. The shift register stores a state of the light sensing element and outputs a series of bits indicating the state of each light sensing element.

Abstract: A method for determining a height of a sash opening formed by a movable sash in a fume hood. The method includes providing a laser device on the hood and providing a reflector on the sash. In addition, the method includes positioning the sash in an open position to form the sash opening and measuring a first distance between the laser device and the reflector when the sash is in the open position. The method also includes calculating the sash height based on the first distance.

Abstract: An arrangement for use in a switching power supply includes a power supply output line, a current sensing circuit, and a feedback circuit. The output line is operably coupled to an output winding of a transformer. The transformer has a first winding operably connected to a switching device configured to be switched in accordance with a first control signal. The current sensing circuit is operable to generate a current signal that is representative of current on the output line. The feedback circuit is operable to generate a feedback signal as a function of the current on the output line. The feedback signal has a first relationship with respect to the current when the current is below a threshold, and has a second relationship with respect to the current when the current is above the threshold.

Abstract: According to the present invention, a fail-safe circuit for controlling an actuator is provided with an input voltage which is rectified and converted to a DC voltage. The DC voltage is boosted to a high level, and high voltage storage capacitors are charged at this high voltage level resulting in smaller, less expensive capacitors. The high voltage from the storage capacitors is then converted back to a smaller DC voltage to drive the motor of the actuator. Reduced size and increased energy storage is based on the relationship between capacitance and voltage in the equation: E=½ CV2.

Abstract: A thermostat control having improved user controls wherein an analog version contains a binary coded switch for selectively setting a setpoint temperature. The binary coded switch is configured to have discrete positions corresponding to a plurality of setpoint temperature settings. It contains, among other things, a resistor network configured to produce a setpoint signal indicative of the binary coded switch position and a setpoint adjust switch for setting the binary coded switch position. Also, digital version having a man-machine interface port, wherein point information from a controller can be viewed and modified with the thermostat control device controls when a hardware passkey is inserted into the man-machine interface port.

Abstract: A thermostat control having improved user controls wherein an analog version contains a binary coded switch for selectively setting a setpoint temperature. The binary coded switch is configured to have discrete positions corresponding to a plurality of setpoint temperature settings. It contains, among other things, a resistor network configured to produce a setpoint signal indicative of the binary coded switch position and a setpoint adjust switch for setting the binary coded switch position. Also, digital version having a man-machine interface port, wherein point information from a controller can be viewed and modified with the thermostat control device controls when a hardware passkey is inserted into the man-machine interface port.

Abstract: A temperature independent dosimeter is provided for measuring an amount of irradiation of a predetermined frequency. A photodiode (24) operating in its photovoltaic mode is irradiated with the irradiation to produce a signal that is amplitude-proportional to the amplitude of the irradiation. The signal is converted by a pair of operational amplifiers (89, 96) to a plurality of pulses that are proportional in frequency to the amplitude of the signal. The plurality of pulses is counted by a counter (20) and the irradiation is terminated when the count reaches a predetermined amount.

Abstract: A constant current battery charging circuit is provided by which the battery receives a full charge until the battery voltage reaches a threshold. When the battery voltage is above the threshold, the battery receives a trickle charge. The actual battery voltage is compared with a reference voltage to determine whether the full charge circuit should be in operation. Hysteresis is provided for preventing a rapid on/off operation around the threshold. The reference voltage is compensated for temperature variations. The hysteresis system and temperature compensation system are independent of each other. A separate test circuit is provided for testing the battery voltage. During testing of the battery, the full charge circuit is inoperative.

Abstract: A process and device are provided for detecting frequency variations of waveforms (10). The waveform (10) is sensed and a first signal (16) is provided with each occurrence of the sensed waveform (10). Each time that the first signal is provided, a measuring pulse (24) that is different in duration than the sensed waveform (10) is provided. The sensed waveform (10) and the measuring pulse (24) are simultaneously transmitted to a gate (28) which provides a signal at its output to indicate if the frequency of the sensed waveform has varied more than a predetermined amount.