We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
(Continued from page 229)
110V
60
mA.
MS).
4 X
Fig. 3
denser is not shorted, by testing with d.c. and a high-resistance voltmeter. The condenser is then connected at the points marked "X" in Fig. 3, and the potential is adjusted to 100 volts. The reading on the milliammeter is noted, and the value of the condenser calculated from the formula given above.
"The capacity meter is, of course, easily calibrated, and Fig. 4 shows the calibration for a 100-volt 60-cycle current, the capacities at different current readings being indicated. In calibrating the chart for different voltages or frequencies, it is necessary only to obtain two points and connect them with a straight line, extending the line to the limits of the chart. Intermediate and exterpolated values will be indicated correctly on the line.
"It is, of course, possible to measure smaller condenser values by lowering the voltage and using a microammeter. However, for accurate measurements of small values a capacity bridge is preferable."
100 200 300
A.C. MILLIAMPERES
Fig. 4
Resonance Indicator
"The following arrangement may be readily built up in the average service shop and is most useful in checking the output ■of receivers and as a resonance indicator in aligning tuning condensers. The circuit is shown in Fig. 5. I use a Jewell 0-1 milliammeter and a fixed carborundum detector.
INPUT
>SEC.
FIXED CRYSTAL DETECTOR
Fig. 5
The ratio of the a.f. transformer is four to one. An oscillator, of course, is used with the indicator for condenser adjustments." O. E. Faulkner, N. Little Rock, Ark. (Continued on page 233)
INCE the inception of modern radio amplification the engineering laboratories of Thordarson have developed hundreds of transformers used in solving the problems of sound reproduction.
Standard units include those for coupling a microphone, a phonograph pickup or a radio tuner into any type of audio frequency amplifier.
Other units are available for coupling the output of an amplifier into transmission lines or directly into loud speakers.
Still other units allow coupling from any line into loud speakers or into additional amplifiers.
Your own work may be made easier and more profitable if you make use of Thordarson engineering service as applied to Thordarson transformers, chokes and amplifiers.
Tell us of your requirements and let us submit suggestions for an installation which will add to your good reputation.
Transformer Specialists Since 1895
Microphone Transformers Line to Tube, Tube to Line, Line to Line Mixing Transformers Coupling Reactors Filter Chokes Impedance Matching Transformers Speaker Coupling Transformers Complete Amplifiers
Thordarson Electric Manufacturing Company
Huron, Kingsbury and Larrabee Streets, Chicago, III., U. S. A.
• FEBRUARY 1 930 •
• 231