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Donald K Zahrte

from Nekoosa, WI
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Donald Zahrte Phones & Addresses

  • 4412 State Highway 173, Nekoosa, WI 54457 (715) 886-2955

Resumes

Resumes

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Donald Zahrte

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Location:
e7556 State Rd, Reedsburg, WI
Industry:
Motion Pictures And Film
Work:
Sound Devices, LLC - Reeedsburg, WI. since Apr 2012
Electrical Product Design & Developement / Sustaining Engineer
Renaissance Learning Inc. - Renaissance Learning Inc. Apr 2001 - Apr 2012
Senior Design Engineer
Best Power - Best Power Jul 1983 - Apr 2001
Senior Design Enginner
Education:
Western Wisconsin Technical College 1981 - 1983
Associate's degree, Electrical Power Engineering
Skills:
Hardware
Analog
Hardware Architecture
Digital Electronics
Product Development
Power Electronics
Electronics
Electrical Engineering
Engineering
Pcb Design
Manufacturing
Power Supplies
Troubleshooting
Engineering Management
Electrical Design
Donald Zahrte Photo 2

Power Electronics Engineer

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Location:
Nekoosa, WI
Work:
The Vollrath Company
Power Electronics Engineer
Education:
Western Technical College - Company 1981 - 1983
Associates

Publications

Us Patents

Device And Method For Inspecting Markings

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US Patent:
20030044091, Mar 6, 2003
Filed:
Sep 4, 2001
Appl. No.:
09/946797
Inventors:
Mark Swanson - Wisconsin Rapids WI, US
William Apperson - Renton WA, US
Donald Zahrte - Necedah WI, US
International Classification:
G06K007/10
US Classification:
382/321000
Abstract:
A device and method for reading optical marks are disclosed. The device, an optical mark reader (OMR) has an array of photo sensors with light-emitting diodes (LEDs), which are driven by digital-to-analog converters (DACs), which are in turn controlled by a microcontroller. When calibrating the OMR, the sensors read a white card, and the microcontroller adjust the DACs so that the outputs of all sensors are at a voltage close to the saturation points of the photo-transistors in the sensors so that the maximum useable ranges of the sensors are utilized. The sensors then read one or more patterns of known grayscales and their response voltages are recorded. The microcontroller generates an array of voltage values as a function of grayscale for each sensor and store the values in a memory device. When reading an optical marks, the sensor output voltage in response to a mark is looked up in the table of voltages values stored in the memory device to determine the grayscale of the mark. Various algorithms may be employed to calculate an apparent grayscale to allow the test taker's true intent be ascertained without requiring the test taker to make a perfect mark.

System For Detecting Markings

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US Patent:
20090232419, Sep 17, 2009
Filed:
Mar 11, 2009
Appl. No.:
12/401988
Inventors:
Mark R. SWANSON - Wisconsin Rapids WI, US
Donald K. Zahrte - Necedah WI, US
Peter William Jungwirth - Wisconsin Rapids WI, US
Assignee:
Renaissance Learning, Inc. - Wisconsin Rapids WI
International Classification:
G06K 9/20
US Classification:
382321
Abstract:
A marking detection system detects markings on a printed medium, such as pencil markings in bubbles on the printed medium. The marking detection system includes a circuit board with a plurality of components thereon, including an optical subsystem and an electronic subsystem including circuitry. The marking detection system further includes a shroud for optically isolating a plurality of emitting and detecting elements of the system.

Uninterruptible Power Supply And Ferroresonant Transformer For Use Therewith

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US Patent:
62187449, Apr 17, 2001
Filed:
Mar 22, 2000
Appl. No.:
9/532226
Inventors:
Donald K. Zahrte - Necedah WI
Peter Jungwirth - Wisconsin Rapids WI
Assignee:
Powerware Corporation - Raleigh NC
International Classification:
H02J 700
US Classification:
307 64
Abstract:
A line-interactive single conversion uninterruptible power supply (UPS) utilizing a multiple tapped ferroresonant transformer and a square wave PWM inverter is presented. During normal utility line operation, the line voltage is not modified in any way, except for ferroresonant filtering and regulation. Tap control circuitry insures proper tap selection based on the utility input voltage. During tap transitions in utility out of specification operation, a second power source, such as an inverter, is operated to provide output power to the connected loads. The control of the inverter switching angles may be accomplished through a look-up table. This look-up table contains the converter pulse widths for monitored battery voltage. No output voltage feedback is required. Based on the inherent regulation provided by the ferroresonant transformer, the PWM control may be accomplished in course steps.

Uninterruptible Power System

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US Patent:
56024622, Feb 11, 1997
Filed:
Feb 21, 1995
Appl. No.:
8/391761
Inventors:
Frederick A. Stich - Wisconsin Rapids WI
Thomas G. Hubert - Necedah WI
David L. Layden - New Lisbon WI
Donald K. Zahrte - Necedah WI
Assignee:
Best Power Technology, Incorporated - Necedah WI
International Classification:
G05F 116
H02J 700
H02J 900
US Classification:
323258
Abstract:
An uninterruptible power system has a transformer with a primary connected to input terminals, a secondary connected to output terminals, a static switch connected between the input terminals and the primary, and an auxiliary primary connected to an inverter which is supplied by a battery to provide output voltage to the output terminals when a main AC power system connected to the input terminals has failed. The primary has multiple taps at different voltage levels and a buck-boost winding. The taps of the transformer are switched and the buck-boost winding is controlled to provide either buck, boost, or pass-by to allow control of the output voltage from the transformer to within a few percent of a desired voltage level despite large changes in the input voltage. A battery charger coupled to the auxiliary primary operates as a boost converter to provide current to charge the battery at a current level which tracks the input voltage from the AC power system, thereby providing a substantially unity power factor to the AC power system. The voltage control of the output voltage also controls the voltage at the output of the auxiliary primary to which the battery charger is connected, whereby the voltage applied to the charger is substantially regulated and the output power of the charger itself is substantially regulated.

Standby Power System

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US Patent:
57903913, Aug 4, 1998
Filed:
Nov 29, 1996
Appl. No.:
8/758412
Inventors:
Frederick A. Stich - Wisconsin Rapids WI
Peter W. Jungwirth - Wisconsin Rapids WI
Donald K. Zahrte - Necedah WI
Assignee:
General Signal Corporation - Stamford CT
International Classification:
H02M 3335
H02J 300
H02J 700
US Classification:
363 24
Abstract:
A standby power system is provided having power conversion, output voltage control, and line-fault detection systems that make possible a significant reduction in the cost of the system. The standby power system provides backup power to a load, such as a computer system, when main AC line power fails. A system DC battery voltage is converted to an AC output voltage signal at line voltage levels by a power conversion system including a high frequency push-pull inverter, a light-weight low-cost high frequency transformer, a rectifier, and a line frequency inverter. The high frequency inverter is controlled to provide high frequency battery voltage pulse bursts separated by low frequency zero voltage dead times which are boosted by the transformer to line voltage levels and rectified by the rectifier. The line frequency inverter is controlled to provide the rectified line voltage level pulse bursts to the standby power system output in the form of a stepped square wave output signal at line frequencies. Rms and peak output voltage control is provided by a system controller based on a single digital output voltage control signal.

Back-Up Uninterruptible Power System

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US Patent:
53155335, May 24, 1994
Filed:
May 17, 1991
Appl. No.:
7/702733
Inventors:
Frederick A. Stich - Wisconsin Rapids WI
Donald K. Zahrte - Necedah WI
Richard V. Baxter - Appleton WI
Douglas C. Folts - Mauston WI
Thomas G. Hubert - Necedah WI
Juan M. Medina - Wisconsin Rapids WI
William J. Hazen - Wisconsin Rapids WI
Edward G. Beistle - Appleton WI
Assignee:
Best Power Technology, Inc. - Necedah WI
International Classification:
G06F 1520
US Classification:
364480
Abstract:
A back-up uninterruptible power system has a power supply path from input terminals connected to AC power system lines to normally supply power to a load. Upon the occurrence of a line fault, a static switch in the power supply path interrupts the connection between the AC power lines and the load and an inverter is turned on to provide power derived from an auxiliary battery through a transformer to the power supply path to supply AC power to the load. By using the static switch, switching from line connection to backup power can be done quickly, within a half cycle, so that substantially no interruption of the output waveform is observed. The inverter can be operated to provide a commutation pulse to the SCRs in the static switch to commutate an SCR which might otherwise continue conducting after the triggering signals to the gates are cut off and before the inverter supplies the AC power to the load. A relay connected between the input terminals and the static switch is controlled to open relay contacts after the static switch has interrupted the current flow to the load, thereby providing positive electrical isolation of the AC power system from the uninterruptible power system while allowing the mechanical relay contacts to switch only during times of no current. Line fault detection is carried out by creating a digital waveform composed of an average of prior cycles of the AC input waveform, converting the stored waveform to an analog signal, and comparing it with the present input signal in phase lock therewith to detect deviation of the input signal from the reference waveform.

Dynamic Voltage Regulation Stabilization For Ac Power Supply Systems

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US Patent:
57291209, Mar 17, 1998
Filed:
Dec 30, 1996
Appl. No.:
8/781896
Inventors:
Frederick A. Stich - Wisconsin Rapids WI
Donald K Zahrte - Necedah WI
Gregory C. Kohls - Nekoosa WI
Robert R. Davidson - Mauston WI
Assignee:
General Signal Corporation - Stamford CT
International Classification:
G05F 1613
US Classification:
323237
Abstract:
Instabilities in the output voltage provided from an AC power supply system such as an uninterruptible power supply connected to a power factor correcting load are suppressed by a dynamic voltage regulation stabilizer system which is connected across the output lines from the power supply system to the load. The DVR stabilizer system includes a rectifier connected to the power supply system output lines. A capacitor is connected across the output nodes of the rectifier. Switching devices form a bridge that connects the capacitor to the output lines. Selected switching devices in the bridge are turned on for a selected duration encompassing the time of the peak of each half-cycle of the AC voltage waveform provided by the power supply system. During normal operation, where the peak AC voltage from the power supply system is substantially constant, the capacitor charges up through the rectifier to a voltage level near the peak value of the AC voltage waveform. When the peak AC voltage level rises above the normal peak level, the capacitor clamps the voltage across the output lines at a value near the steady state peak value.

Inverter Having Center Switch And Uninterruptible Power Supply Implementing Same

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US Patent:
62662600, Jul 24, 2001
Filed:
Sep 1, 2000
Appl. No.:
9/653383
Inventors:
Donald K. Zahrte - Necedah WI
David L. Layden - New Lisbon WI
Frederick A. Stich - Wisconsin Rapids WI
Douglas C. Folts - Baraboo WI
Assignee:
Powerware Corporation - Raleigh NC
International Classification:
H02M 75387
US Classification:
363132
Abstract:
Presented is a center switching circuit and an inverter and an uninterruptible power supply (UPS) utilizing same. The center switching circuit selectively enables and disables power flow to and from the bus capacitors of an inverter or UPS. As such, the center switching circuitry effectively removes the bus capacitors from the circuit. This allows operation of the inverter or UPS in a high efficiency mode whereby input line voltage may be passed essentially without compensation to the output when the center switching circuit is open. Modulation of the center switching circuit during this mode provides soft charging of the bus capacitors so that they are available to source current in a double-conversion or DC boost mode upon degradation or loss of the line voltage. To supply output power from the bus capacitors, the center switching circuit is closed to associate these capacitors with the neutral. Fault isolation is provided during operation by opening the center switching circuit to prevent power flow from the bus capacitors.
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Donald K Zahrte from Nekoosa, WI Get Report