US2923876A

US2923876A - Biased diode function generator

Info

Publication number: US2923876A
Application number: US389541A
Authority: US
Inventors: John I Daspit
Original assignee: Gilfillan Bros Inc
Current assignee: Gilfillan Bros Inc
Priority date: 1953-11-02
Filing date: 1953-11-02
Publication date: 1960-02-02
Anticipated expiration: 1977-02-02

Description

Feb. 2, 1960 J. l. DAsPn' 2,923,876

BIASED DIODE FUNCTION GENERATOR Filed NOV. 2, 1953 2 Sheets-Sheet 1 '-I /50V Fw. l 1 082 ZIB Q wel@ *IOSV /500JL W 252 25"* goe 47/2 256 47e sa@ 2?- ArfraeA/EVS' Feb. 2, 1960 J. l. DAsPlT 2,923,875

BIASED mom: FUNCTION GENERATOR Filed Nov. 2. 1953 2 Sheets-Sheet 2 United States Patent() BIASED DIODE FUNCTION GENERATOR Application November 2, 1953, Serial No. 389,541

4 Claims. (Cl. 323-16) The present invention relates to improved means and techniques for developing certain predetermined voltage variations and more specifically to a network involving unidirectional conducting elements, one or more of which is biased in such a manner that the voltage developed at the output of the network is not necessarily directly proportional to the magnitude of the voltage applied to the input of the network.

It is oftentimes desirable to develop an output voltage in a network which does not follow linearly the magnitude of the voltage applied to the input of the network, as for example in instrumenting computers of the character described and claimed in my copending patent application Serial No. 389,542, tiled November 2, 1953, and assigned to the present assignee. Thus, it may, for example, be desirable to develop the voltage representative of the rst quarter or 90 portion of a sine wave or to produce a voltage representative of other trigonometric variations such as, for example, the inverse secant of a particular angle. The means and techniques described herein are particularly applicable for those general purposes. It is understood that the means and techniques described herein are applicable to the generation of voltage variations which, when represented graphically, have a concave portion extending either in the downward direction or in the upward direction, or lthe output variations, represented graphically, may have a concave portion thereof extending downwardly as well as a concave portion extending upwardly.

It is'ther'efore a general object of the present invention to provide improved means and techniques whereby the aforementioned indicated results may be obtained.

Another object of the present invention is to provide a network of this character which involves relatively few circuit elements.

Another object of the present invention is to provide improved apparatus of this character which is easily adjusted to obtain the desired voltage variations.

Another object of the present invention is to provide improved apparatus of this character, the operation of which is simple to understand thereby allowing quick adjustment.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. This invention itself, both as to its organization and manner of operation, together with further objects and advantages thereof, may be best understood by reference to the following description taken in connection with the accompanying drawings in which:

Figure 1 illustrates a network embodying features of the present invention.

Figure 2 illustrates in graphical form the voltage variation obtained using the network illustrated in Figure 1.

Figure 3 illustrates another network embodying features of the present invention.

Figure 4 illustrates in graphical form the voltage varia` tion obtained using the network illustrated in Figure 3.

Figure 1 illustrates a so-callel biased diode function ICC generator which develops a voltage variation represented in Figure 2 by a curve concave in a downward direction.

For these purposes, a series of

diodes

200, 201, 202, 203, 204, 205, 206, 207, 208 and 209, each having their anodes interconnected and their cathodes biased to different potentials, are used. The input voltage is supplied between the

terminals

210, 212 and the output voltage appears across the terminals 214,l 215, the

terminals

210 and 215 being grounded. The anode of each of the diodes is connected to the terminal 214, and terminal 214 is connected to terminal 212 through resistance 217. The voltage source 216 has its negative terminal grounded and its positive terminal is returned to ground through the resistance 218 and the gaseous Voltage regulating tube 219 serving to maintain a potential of approximately 105 volts across the leads 220 and 222. A series of voltage dividing

networks

230, 231, 232, 233, 234, 235, 236, 237, 238 and 239 are each connected between the leads 220 and 222 and each of such voltage dividing networks has a corresponding adjusting

tap

230A, 231A, 232A, 233A, 234A, 235A, 236A, 237A, 238A and 239A. These taps are connected through

corresponding resistances

240, 241, 242, 243, 244, 245, 246, 247, 248 and 249 to corresponding cathodes of

tubes

200, 201, 202, 203, 204, 205, 206, 207, 208 and 209. If desired, resistance 249 may have a value of zero ohms. The resistances have the n values indicated in Figure l and, in this respect, the symbol K refers to one thousand ohms and the symbol M refers to one million ohms. it is thus observed that rcsstance 217 has a value of 100,000 ohms, resistance 240 has a value of 4.7 megohms, resistance 241 has a value of 2.2 megohms, resistance 242 has a value of 2.5 megohms, resistanc'e 243 has a value of 820,000 ohms, etc.

It is observed that as the input voltage applied to

terminals

210, 212 increases progressively, more and more of the diodes 200--209 are, in that order, rendered conductive so as to produce an increased voltage drop across resistance 217. However, the voltage drop across resistance 217 does not increase linearly out increases in a nonlinear manner as shown in Figure 2. The various resistances are so adjusted that the variation in output voltage appearing across the

output terminals

214 and 215 has the desired variation, such variation in Figure 2 being the first portion of a sine wave.

It is observed that in Figure 2 the abscissa of the curve which extends concave downwardly is the input voltage and the corresponding ordinates of the curve are corresponding output voltages appearing at the

terminals

215, 214.

It is observed that the rst diode 200, in the absence of any voltage applied to the

input terminals

210, 212, is in a nonconducting condition and that a corresponding zero voltage appears at the

output terminals

214, 215.

The curve illustrated in Figure 2 is deiined by essentially ten points, one point corresponding to each of the ten diodes shown in Figure 1. The general shape of the curve illustrated in Figure 2 may thus be altered by adjustment of the diiferent points thereon, such adjustment being provided by the adjustable taps 230A-239A, both inclusive. It is observed that each point on such curve represents the condition wherein the corresponding diode is rendered conducting. Thus, when the input voltage is raised from zero volts to a value of 15.64 volts, the first diode 200 is rendered conductive and such diode 200 remains in a conductive state for all values of input voltage above such vaiue of 15.64 volts. When the diode 200 becomes conductive, a current ows through a path which includes the terminal 212, resistance 217, diode 200, resistance 240, tap 230A, a selected portion of the voltage dividing network 230, and the lead 220, and terminal 210. Such current tlow through resistance 217 produces a corresponding voltage on the output terminal 214. Assuming that the input voltage is then raised to a value of 30.90 volts, the second diode 201 is rendered conductive thereby to provide a second path for current flow, such second path including the common resistance 217.

When and as the input voltage is further increased, the remaining diodes, in turn, are rendered conductive thereby to provide additional paths for the current ow for increased voltage drop across resistance 217.

Figure 3 illustrates a network for obtaining a voltage variation which is concave in the upward direction instead of being concave in the downward direction. The network of Figure 3 includes the

input terminals

300, 301 and the output terminals 302,303, the

terminals

301 and 303 being grounded. The resistance 305 is connected between

terminals

300 and 302. A plurality of unidirectional conducting devices in the form of hot cathode diodes, each has its cathode connected to the terminal 3 02. The anodes of

such diodes

308, 309, 310 and311 are each returned to ground through a

corresponding network

318, 319, 320 and 321 comprising a resistance serially connected with a voltage source. The negative terminal of each of such sources is grounded. The voltages of these sources are each different and normally maintain the

diodes

308, 309, 310 and 311 in a conducting state, in the absence of a voltage applied to the

input terminals

300, 301.

When the voltage applied to the

terminals

300 and 301 is increased so that the terminal 300 becomes progressively more positive, the

diodes

308, 309, 310 and 311 are progressively and in turn rendered nonconductive.

Thus, when the potential on the terminal 300 has the value corresponding to the voltage E2 in Figure 4, the rst diode 30S is rendered nonconductive; when the input voltage on the terminal 300 assumes the value represented by E3 in Figure 4, the second diode 309 is rendered nonconductive; when the input voltage on terminal 300 is increased further tothe value represented by E4 in Figure 4, the third diode 310 is rendered nonconductive; and so forth. These values of voltages E2, E3 and E4 are adjustable by adjustment of the corresponding bias voltages E9, Em, En and E12 in the

networks

318, 319, 320 and 321, respectively.

While the particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims s to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. A non-linear network of the character described comprising: va pair of input terminals and a pair of output terminals, a voltage dropping resistance connected between one of said input terminals and one of said output terminals, a plurality of diodes, each vhaving one of its terminals connected to said one output terminal, a plurality of voltage sources of different magnitudes and each having one of its terminals connected to the other one of said input terminals and also to the other one of said output terminals, the other terminals of said voltage sources being connected to corresponding other terminals of said diodes so that the current which ows through a corresponding diode flows only through a corresponding voltage source.

2. A network as set forth'in claim 1 in which said diodes are normally nonconducting but are rendered conducting, in turn, upon increase of voltage applying to said input terminals.

3. A network as set forth in claim 1 in which said diodes are normally conducting but are rendered nonconducting, in turn, upon increase of voltage to said input terminals.

4. A network as set vforth in claim 1 in which said voltage sources comprise individual potentiometer resistances having taps connected individually to corresponding terminals of said diodes, a common power source having one of its terminals connected to said other output terminal and the other one of its terminals connected to an outside terminal of each ofA said particular resistances, the other outside terminals of said potentiometer resistances each being connected to said one input terminal.

References Citedy in the tile o f this patent UNITED STATES PATENTS 1,711,658 Sprague May 7, 1929 1,776,822 Strieby Sept. 30, 1930 2,434,155 Haynes Jan. 6, Y1948 2,548,913 Schreiner et al. Apr. 17, 1951 2,567,691 Bock Sept. 11, 1951 2,581,124 Moe Jan. 1, 1952 2,612,630 Greenleaf Sept. 30, 1952 2,697,201 Harder Dec. 14, 1954 2,831,107 Raymond Apr. 15, 1958