Device, which operates from 28 V dc, has four sections, a preregulator, a dc-to-dc converter, a current regulator, and a high voltage starter. The unique characteristics of the individual sections are described

Goodwin, J. E.

English

NASA Technical Reports Server

ode 
amp 
December 1970
	
Brief 70-10684 
NASA TECH BRIEF 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage commercial 
application. Tech Briefs are available on a subscription basis from the National Technical Information Service, Springfield, 
Virginia 22151. Requests for individual copies or questions relating to the Tech Brief progam may be directed to the Tech-
nology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Small, Efficient Power Supply for Xenon Lamps
Figure 1. Schematic Diagram of Current Regulator 
The unusual power demands of xenon lamps—
constant voltage of 15 V when "on," supply voltage 
of 40 V when "off," and ionizing source of 25 kV pulse 
—can bernet with a new power source, smaller and more 
efficient than previous models. 
The device, which operates from 28 V dc, has four 
sections: a preregulator, a dc-to-dc converter, a cur-
rent regulator, and a high-voltage starter. Although the 
individual sections are basically conventional, they, 
each have specific characteristics that are somewhat 
unique.
The preregulator, for instance, requires fewer com-
ponents than other models, and can operate at fre-
quencies between 100 and 200 kHz with an efficiency 
of 90%. At high frequencies, smaller transformers and 
filter-capacitors can be used. 
In the dc-to-dc converter, voltage feedback and cur-
rent feedback are both used. The current feedback is 
applied from a separate transformer in series with the 
voltage-feedback transformer The converter is free 
running with either feedback, but voltage feedback pre-
dominates at high loads and current feedback predom-
(osnhirsLEd Os criesri) 
-I
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned .rights.
https://ntrs.nasa.gov/search.jsp?R=19700000662 2020-03-17T01:03:19+00:00Z
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Current Limiter 
Figure 2. Schematic Diagram of Starter Circuit 
mates at low loads. The unit provides 40 V for lamp 
operation and —5 V for control of the current regulator 
(Fig. I), a ripple-type device. 
Another lead from the transformer's —5 V winding 
provides a 10-V square wave to drive the high voltage 
starter. Adding secondary windings to the transformer 
can produce different voltages for different purposes. 
The high-voltage lamp starter (Fig. 2) has a balanced 
voltage-doubling circuit driven by a 10-V peak-to-
peak square wave supplied by the converter. The wave 
is transformed at 160 V peak-to-peak before the volt-
age is doubled. The resulting 160 V signal is stored 
across the voltage-doubling capacitors until the relaxa-
tion oscillator fires a silicon-controlled rectifier. The 
rectifier discharges the capacitor's energy through the 
primary of a high-voltage pulse transformer. The 
oscillator allows the voltage-doubling capacitors to 
charge and discharge until the xenon lamp lights. The 
starter-inhibiting circuit then provides a positive voltage
to the gate of an N-channel field-effect transistor. The 
transistor turns on and shorts the timing capacitor in 
the oscillator so that further firing of the rectifier is 
prevented. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Manned Spacecraft Center, Code BM7 
Houston, Texas 77058 
Reference: TSP70- 10684 
Patent status: 
No patent action is contemplated by NASA. 
Source: J. E. Goodwin of 
Martin-Marietta Corp. 
under contract to 
Manned Spacecraft Center 
(MSC-13637)
. 
Brief 70-10684	 Category 01


Small, efficient power supply for xenon lamps

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