INSTRUMENTATIΟΝ The sensitivity of a n e w electronic vertical scale i n d i c a t o r is almost eight times that of a c o n v e n t i o n a l g a l v a n o m e t e r
rpiHis electronic continuous null-point balance circuit has been in extensive use for a long time. Indicators, con trollers, and recorders using this princi ple are available in great variety, and a new version or combination of functions is offered to the scientific and technical public almost monthly.
vertical rotating scale are new. Tem peratures, rotational speeds, and any phenomena which can be converted into millivolts are indicated rapidly, pre cisely, and directly. The instrument is 6.5 inches wide and hence five of the \ r ertical scale instruments can be mounted in the panel space needed for two comparable type circular scale in dicators. With respect to response speed, two models are available, one with 12-second full scale travel and the other with 4.5-second full scale travel. For a movable enclosed scale with fixed index point, this type of scale is read easiest, fastest, and with the least error. The scale has black numbers and divi sion lines on a white drum rim and even, nonglare edge lighting is provided by two Figure 2
Figure 1 One of the newest offerings is the Honeywell Electronik vertical scale in dicator, the details of which we are able to present at this time through the courtesy of Paul A. Feeger, Albuquerque office, Minneapolis-Honeywell Brown Co. The instrument, a front view of which is shown in Figure 1, uses the standard electronic continuous nullpoint balance system of potentiometric measurement. The compact case and VOLUME
2 7, N O .
1, J A N U A R Y
1955
by Ralph H. Müller
fluorescent lamps. The scale is 28 5 / 8 inches long. Approximate readings can be made at a distance of several feet and for close observation, twin hairlines prevent parallax errors. The sensitivity of these instruments is better than 0.04% of full scale, almost eight times the sensitivity possible with conventional galvanometers. As a result of the continuous balancing action, any change in the input signal causes the drum scale to rotate immediately to the new balance position. Standardization is accomplished by pressing the button switch at the lower right side of the front cover. This switches the instrument to a standardizing circuit in which the balancing motor drives a battery rheostat until dry cell voltage equals standard cell voltage. Three terminals on the front cover permit calibration with a reference standard and external measurement of input millivolts from the front of the panel. Further details of the arrangement of components may be seen in Figure 2, in which the front panel has been pulled out. Details of the slide-wire with attached scale are invisible and some of the electronic components of the servobalancing system are immediately behind it. Over-all dimensions to within 37 A
INSTRUMENTATION
ILLCO-WAY
ionXchange LABORATORY SIZE OF CARTRIDGE DE-IONIZER GIVES MINERAL-FREE WATER The latest development in ionXchange equipment is the mixed-bed de-ionizer, which combines both anion and cation resins in one vessel or tank. The unit shown below is a miniature model of such a de-ionizer, made up in such a manner as to be an ideal accessory in any laboratory where mineralfree water is wanted occasionally in compara tively small quantities. The ILLCO-WAY Cartridge De-Ionizer consists of a plastic tubular column containing 3 lbs. of mixed resin. When the resins are exhausted, as shown by a change in color, the entire cartridge can be discarded and a fresh one substituted. N o electrical connections are needed. The column can be clamped, as shown, in any convenient location or manner. RESEARCH MODEL Produces water comparable to that obtained by triple dis tillation. Removes all ionizable solids, including silica and CO3. CAPACITY -
450 grains
FLOW RATE -
5
gph
PRICE (FOB Rockford) — $12.50 BRACKET (Extra) — $5.00 UNIVERSAL MODEL Produces water comparable to that obtained by single dis tillation. Removes all ioniz· able solids except silica and CO2.
CAPACITY - w o grains FLOW R A T E - s gPh PRICE (FOB Rockford)-$9.75 BRACKET (Extra) — $5.00 Write for fully descriptive literature Bulletin CA-254
ILLINOIS WATER TREATMENT CO.
ionXchange ILLCO-WAY
835 CEDAR ST. ROCKFORD,
Models are available in five standard pyrometer ranges from —20° to 2400° F. for use in the different ranges with copper-constantan, iron-constantan, or Chromel-Alumel thermocouples. Four standard ranges are also offered, reading in millivolts: 0-100, 0-150, 0-200, or - 1 0 0 to 0,0 to +100. Additional details on this and related indicators are available from the Indus trial Division, Minneapolis-Honeywell Regulator Co., Wayne and Windrim Aves., Philadelphia 44, Pa., or any of the company's regional offices or foreign subsidiaries.
ILLINOIS
NEW YORK OFFICE: 141 Ε. 44ΤΗ ST., NEW YORK 17, N.Y. CANADIAN DIST: PUMPS & SOFTENERS, LTD. LONDON.ONT.
Circle No. 38 A on Readers' Service Card, page 43 A
38 A
the nearest eighth inch are 153/e inches high, 6 Ά inches wide, and 175/s inches deep. Net weight is 60 pounds. There are several optional features: It can be fitted with two cam-operated micro switches providing SPDT action at any two points on scale. The microm eter adjustment of position is within 0.2% full scale. The switches are rated at 1 ampere, 115 to 120 volts a.c. noninductive load, or 1.5 amperes, 30 volts d.c. A thermocouple and component fail ure-protection feature can cause the in strument to act as though the tempera ture were excessively high in the event of thermocouple or extension wire open circuit, or voltage amplifier tube failure. This extra feature is available with all models having thermocouple calibration with spans of 6.0 mv. or greater. The checking terminals on the front panel may be omitted if desired. Additional data on the vertical scale indicator are : Accuracy as a potentiom eter with ±0.02 mv. for spans less than 10 mv. As a resistance thermom eter, within 0.25% of scale span. The sensitivity is V32% of scale span, or 0.005 mv. for spans less than 16 mv. The minimum span is 2.5 mv., which is standard. For information on microvolt spans, the company's Instrumentation Data Sheet No. 10.0-8 should be con sulted. There are 300 to 650 scale divisions on the dial, depending upon span. Operation is on 110 to 125 volts, 60 cycles at 37 watts, and 91.5% power factor.
Tube Driveti Motor Circuits
N u m b e r 10 i n A d v a n c e s i n C h e m i s t r y Series
edited
by the staff
of
Industrial and Engineering Chemistry
Literature Resources For Chemical Process Industries Designed To Help B o t h T h e New A n d T h e Experienced S e a r c h e r Of L i t e r a t u r e F i n d W h a t He W a n t s
Encompassing
:
Symposium on Market Research Sources 14 papers — 117 pages
Literature of Resins and Plastics 7 papers — 39 pages
Literature of Textile Chemistry 6 papers — 67 pages
Literature of Food Industry 10 papers — 86 pages
Literature of Petroleum Chemicals 10 papers — 121 pages
13 General Papers 109 pages sources and how t o use t h e m foreign language problems
24 Page Index 582 p a g e s — p a p e r b o u n d $6.50 p e r c o p y
order
from
Special Publications Dept. A m e r i c a n Chemical Society 1155 Sixteenth Street, N. W. Washington 6, D. C.
Attention is drawn to the manifold possibilities in instrumentation which ANALYTICAL
CHEMISTRY
INSTRUMENTATION
N-M-R-
Completes Your Spectroscopy Team Perplexing chemical problems which resist solution by other methods may often be solved by applying the revolutionary High Resolution n m r [nuclear magnetic resonance) technique — a powerful new member of the spectroscopy team. Varian n m r Spectrometers are being used daily in many laboratories for detailed functional-group analyses of organic and petrochemical mixtures. And in such rapidly expanding fields as silicon, boron and fluorine chemistry, n m r is providing penetrating insight into molecular structures. The newly-styled Model V-4300A High Resolution n m r Spectrometer now incorporates an exclusive Varian "sample spinner." By mechanically rotating the sample during signal observation, tiny magnetic field inhomogeneities can be averaged out. Result: the "resolving power" of the Spectrometer is extended to a higher degree than ever before. THIS IS N-M-R AT W O R K O o S ' S i ' i " ON THE SHIFT IMC CHACAL vnu...
EFFECT OF HYDROGEN
BOND.N
,NTERpRETATION INTERPRETATION •i*A
DATA
Samples. Glacial acetic acid 5056, 25£, and 12% acetic acid in acetone. Signals observed. H
Frequency. 30 mc.
liniiirl·
The proton resonance i r l0 ^ ^ o tô be general y shitted to ™er ™
^
K a the asso-
0f
Siation. The progressive |tun s η» j n g concenrarboxyl P'oton resonance»"' tion between acetic "ation y results fronr.a ^ P j Z t h e s„W ent (aceacid molecules for each™_er an ) e ( r a c , 0n tone). By P>if " « . " ' i S S i . T drtermln. the vaue ot acetic acid it is possiiui paction. Acetic of the equilibrium constam'or l o n , e x
Sweep rate: 10 milligauss/sec. -^a d ^ e : S o ^ a , n « 3 h " r a i s i — miiarso - W e n^, s .
Zero of reference: CH, group m
_. . - . w c t n
REFERENCE
HUCLEAIMAGNETIC^SO^
FOR
COMPLETE
INFORMATION...
O n Varian's V-4300A High Resolution n-m-r Spectrometer, as well as the Model V-4200 Variable Frequency n-m-r Spectrometer, and associated magnet systems, contact the Special Products Division for:
THE MARK OF LEADERSHIP
V A R I A N P A L O
A L T O
MICROWAVE
TUBES
4,
· · ·
Technical Bulletins Data Sheets η·τη·Γ Table
associates C A L I F O R N I A
— SPECIAL
PRODUCTS
can arise from circuits involving tubedriven motors. A specific instance is to be found in a portable integrating cir cuit for low radioactivity counts de scribed by A. H. Ward [J. Sci.Instr., 31, 429 (1954)]. The success of this par ticular instrument is largely due to a low-inertia motor manufactured by Electro Methods, Ltd. This tiny de vice will start rotating when a current of 100 μΆ. is passing through it. In the first of two circuits, anode pulses from a halogen-filled Geiger counter operate a normal biased multivibrator pair with the integrating motor in the anode circuit of the second tube. For this arrangement, the shaft rotation is not a linear function of the true counting rate, because, at low rates, the motor actually stops between pulses. In the alternative circuit, pulses are fed to a capacitor shunting the motor through a ger manium diode. Linear integration now results, but there is difficulty at high rates in this method. This paper is an interesting and important contribution to the more general problem of tubedriven motor circuits. These have countless possibilities in instrumenta tion. Several firms in this country are of fering small motors (of the clock variety) which will operate in the plate circuit of receiving tubes. A number of feed-back arrangements are suitable for rendering the motor response linear with input signal. A number of these are under investigation by the writer and may be described in a more suitable medium in the near future. Although integration is the most ob vious application, there are many ex amples of control operations or even of precise measurement in which the motor principle is attractive. This is true in spite of the fact that there have been notable advances in the design and manufacture of electromechanical count ers, to be used alone, or in conjunction with scaling circuits. One of the obvious advantages, from a purely mechanical point of view, is the superiority of rota tional movement over intermittent re ciprocating motion. Excessive wear is the limiting factor in mechanical count ers and therein resides a good part of the explanation.
For further information, circle number 40 A on Readers' Service Card, page 43 A
40 A
ANALYTICAL
CHEMISTRY
