Solid state circuit generating adjustable square wave pulses of sufficient power operates a 28 volt dc solenoid valve at precise time intervals. This circuit is used for precise time control of fluid flow in combustion experiments

Gillett, J. D.

English

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February 1967
	
Brief 67-10022 
NASA TECH BRIEF 
____i_i-- ; ; E-T2• 
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. 
-t	 51tt 
Variable-Pulse Switching Circuit Accurately Controls Solenoid Valve Actuations 
The problem: 
To devise an adjustable switching circuit that will 
operate a 28 volt dc solenoid valve at precise time 
intervals. 
The solution: 
A solid state circuit that generates adjustable square 
wave pulses of sufficient power to operate a 28 volt 
dc solenoid valve.
How it's done: 
The circuit includes a pulse-forming branch (flip-
flop) and sufficient amplification to power the opera-
tionof the solenoid valve from a 28 volt dc source. 
The flip-flop is powered by an independent 22 1/2 
volt battery. Pulse width (on time) can be varied over a 
range of 10 to 40 milliseconds by adjusting potenti-
ometer R 1 . Similarly, the interval between pulses (off 
time) can be varied over a range of 8 to 350 milli-
seconds by means of R2. 
-	 (continued overleal) 
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=19670000022 2020-03-11T20:19:35+00:00Z
Notes: 
1. This type of circuit has been used in conjunction 
with a solenoid valve for precise time control of 
fluid flow in combustion experiments. With a 
suitable arrangement of relays, the circuit can be 
used for sequencing of' multiple flows in various 
processes requiring precise timing. 
2. Inquiries concerning this invention may be directed 
to:
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B67-10022
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D. C. 20546.
Source: J. D. Gillett,
of North American Aviation, Inc.

under contract to

Marshall Space Flight Center
(M-FS- 1895) 
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Brief 67-10022	 Category 01


Variable-pulse switching circuit accurately controls solenoid-valve actuations

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