A coil can be wound on a magnetic core in one of only two directions. There are several dot-conventions which can bo used to indicate which direction is desired. A simpler symbol, which is quicker to draw and easier to follow, is proposed: The "mirror symbol", which "reflects" current to find resultant flux

Mayer, Rollin P.

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6889 Engineering Note E-472 Page 1 of 3 Digital Computer Laboratory Massachusetts Institute of Technology Cambridge, Massachusetts TITLE: THE MIRROR: A. PROPOSED SIMPLIFIED SYMBOL FOR MAGNETIC CIRCUITS.. To: 6889 Engineers From: R. P. Major Date: August H , 1952 Abstract: A coil can bo wound on a magnetic core in one of only two directions. There are several dot-conventions which can bo used to indicate which direction is desired, A simpler symbol, which is quicker to draw and easier to fol-low, is proposodt Tho "mirror symbol", which "reflects" current to find resultant flux. The Mirror Symbol Figure 1 shows a conventional ceil symbol and tho corresponding proposed mirror symbol. Note that the core is a single line with blocked ends, Tho coil is indi-cated by the short diagonal "mir-ror", which "reflects" applied current to show the direction of tho flux it tends to produce. There are only two directions in which a coil can bo wound, and they are both shown in Figure 1. ¥* +< r-H -WIRE - COIL r-COKE h i FIO, 1 APPROVED FOR PUBLIC RELEASE. CASE 06-1104.F^r - .... .. 1. . - ^ 6889 Engineering Note E-472 Page 2 of 3 Induced Voltages Three simple steps (Figure 2) find the induced volt-ages: (l) Find the direction of positive flux change resulting from iIN or other causes, (2) Go te the end of the cere and bounce off, (3) Return back devn cere and reflect off all mirrors to find positive induced voltages,, i -^. =i0 f, ir-t-A^, THE* km O "(+)" = INDUCED VOLTAGE OR DIRECTION OF RESULTANT CURRENT. FIG. 2 • f Applications Figure 3 shows that a mirror in one place establishes coil direction, and that number of turns, etc., can be indicated (if desired) by any of several ways. Straight core symbols are strongly encouraged. But Figure U shows that a circular core symbol works almost as well. (Remember that you can find outputs only by revers-ing direction, oven though the circle has no "end" to bounce off as in Figure 2). Quadrature field windings can bo shown as in • Figure 5. The sensing pulse tends to decrease the main field, so the flux change is in the other direction. i y<y*— FIG. 3 f •<-5fN5f +** * ) FIG. 5 APPROVED FOR PUBLIC RELEASE. CASE 06-1104.. * " * 6889 Engineering Note E-472 Page 3 of 3 Examples, The examples shown in Figures 6 and 7 shew hew a flip-flep and a stepping register work. These circuits were originally explained in H-1570 (Meeting of July 25, 1952). The "Method ef Operation" shews the flew ef information from input current,to <Z>, to reflected A <t>, to output current, etc. » A s A~»» in M- IS70 (l INTO » T s r r j f UfWAKB^ " o " OVTf »*Nfc-•HMT* 1 ^ o t ©•TFVT CUAR VJIN6, MIRKOR ^e* _ T- *r « T +» s 7^4-CtCA* ' H H t o t STATE * t i 4. r FIG. 6 - FLIP-FLOP • u K f i i N t u r " ' I S C H A R G C *«Font W»i.»*l" 1 A<? , r - * i » !L. 4 A«S t "It A j show, m M-1570 ( i . ' w o > O T SETS + unmo) B — I f "0" RPM/bj USIN6 MIRROR „LAftC>* MVKHIl OF TVA.t CAN 0C f»IW« >F- YOV "rttt J'HV--ti.0SC» « • * CAN or SH»W~ IF V«i; W I S H . WOTE: F L U X WMCTIOWS l » J CRYSTAL t>l*SCTie»S «rr J l f f a r f t f t fV.w, M-IS70, M E T H O f OF eFEHfiijlON •cFo.r _ ^ t ! i _ L . ( » ( « > . : if HI e ) FIG. 7 - STEPPING REGISTER Signed: ft.(? %^AJ^ R. P. layer Apprered: yiilU^^A tUvC^i^C ' W. K. Linvill APPROVED FOR PUBLIC RELEASE. CASE 06-1104.

The Mirror: A Proposed Simplified Symbol for Magnetic Circuits

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The Mirror: A Proposed Simplified Symbol for Magnetic Circuits

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