System that substitutes solar cells directly in the path of the radiation incident on the test volume and uses a dc bridge-null system was developed. The solar cell is affixed to a heat sink mounted on each of three arms for each solar lamp. Control of the radiation from the solar lamps is automatic

Leverone, H.

Mandell, N.

English

NASA Technical Reports Server

November 1968
	 Brief 68-10399 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Automatic Solar Lamp Intensity Control System 
go 
The problem: 
In operating a solar simulation system within a 
thermal vacuum chamber, it is desirable to closely 
control the light sources in order to provide uniform 
and precise irradiation of the test volume. Pre-
vious systems used cadmium sulfide cells (one per 
lamp) as sensors, viewing only reflected light and, 
therefore, nonresponsive to changes occurring in the 
optical train. Also used was an a.c. bridge-null for
each lamp control circuit with a common a.c. refer-
ence highly susceptible to interaction. 
The solution: 
A system that substitutes solar cells directly in the 
path of the radiation incident on the test volume and 
uses a d.c. bridge-null system. 
How it's done: 
A solar cell is affixed to a heat sink mounted on 
each of three arms for each solar lamp. The three cells 
(continued oierleafl 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19680000399 2020-03-12T05:57:13+00:00Z
are connected in parallel across a precision, low tem-
perature coefficient, one ohm resistor mounted under 
the hyperbola. Each solar cell is so positioned that 
the typically hot and cooler areas of lamp intensity 
are monitored. 
Output of the combined detectors for each lamp 
is fed through a potentiometer to the input of a con-
trol amplifier, the potentiometer being used to nor-
malize the outputs of all detectors. An adjustable bias 
opposing solar cell input is also applied to the control 
amplifier. At the desired solar lamp radiation, this 
bias causes the net solar cell current to "null" the 
needle of a contact meter. Adjustable limits about the 
"null" position in the contact meter are positioned to 
form the desired control bandwidth. When the needle 
passes either high or low limit from "null", the limit 
contacts are energized. The contacts of the limit relay 
energize a control relay whose contacts actuate a lead
screw drive motor to move a transformer core in the 
solar lamp power supply to change input power to the 
lamp to restore the preset radiation level.' Control of 
the radiation from the 127 solar lamps is automatic. 
Note: 
Inquiries concerning this innovation may be directed 
to:
Technology Utilization Officer 
Goddard Space Flight Center 
Greenbelt, Maryland 20771 
Reference: B68-10399 
Patent status: 
No patent action is contemplated by NASA. 
Source: Nathan Mandell

and Harry Leverone

(XGS-10017) 
Brief 68-10399	 Category 01


Automatic solar lamp intensity control system

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server