Home Independent Dealers
For those who care about books!  
 Other Areas
Advanced Search
Browse Book Categories
Antiques Collectibles
Browse by Dealer
Author Autographs
Author Awards
Author Biographies
Author Pseudonyms
Collecting Information
Glossary of Terms
Helpful Sites
Publisher Information
Customer Account
Account Log-out
Contact Us
About TomFolio
For Bookdealers
Code of Ethics
Secure Shopping
Privacy Statement
Legal Information
Become a Member
Members Only

 Search Items
By Author:

By Title:

By Keywords:


Advanced Search
Books, Periodicals, Ephemera

Detailed Information for Seller's item number: M10842
Direct Current Amplifier for Measuring Small Circuits, D-C. Amplifier for measuring small direct current Bell Telephone
Author: Eglin, J M
Publisher: Bell Tel. Labs 1929, reprint of paper presented before Amer Phys Soc 1928, publ in J Opt Soc 1929

Bell Telephone Laboratories Reprint B-399 June 1929

Very Good, stapled blue heavy paper wraps, toning to covers along margins, paper clean & unmarked but toning with age and paper acidity; 10 pages; 3-hole punch as issued

D-C Amplifier for Measuring Small Currents, a Description of an Improved Bridge Type of Amplifier for Measuring Small Direct Currents / orig. published in the Journal of the Optical Society of America and Review of Scientific Instruments, vol 18 May 1929.

Abstract , /B>-- A direct-current amplifier consisting essentially of a Wheatstone bridge, having the amplifying tube in one arm and a balancing tube in another, has been described by P I Wold and by C E Wynn-Williams. This circuit has now been developed to give a constant amplification for currents in either direction up to 10, 000 times the lowest measurable value. The amplification and the lowest measurable current are alterable together by changing the resistance introduced between the grid and filament of the amplifying tube. With tubes of high insulation, the amplification can be made as large as 10, 6 and the measurable current as low as 10, -14 ampere. Some improvements of the circuit are, 1) the insertion of a resistance in series with the tube in one arm of the bridge to 'compensate' for variations in plate and grid battery voltages; 2) the suspension of the tubes to protect them from mechanical vibrations; 3) the use of tubes with pure tungsten filaments to avoice changes in contact potentials, and with plates enclosing the filaments completely to lower the effects of wall charges. In a 'null' method of using the circuit the values of the grid resistance and an auxiliary potential introduced in the grid-filament circuit are sufficient to determine the measured current.' (from the abstract in the text)

Price: US$10.00. Quantity available: 1.
 Appr.: | AUD 13.51 CAD 13.33 EUR 9.43 GBP 7.91 JPY 1000 MXN 167 ZAR 143 

  Click button to purchase online.
Contact Dealer   Click button to contact dealer and purchase direct.

Direct Current Amplifier for Measuring Small Cir

Seller and Location:
PO Box 66
Torreon, New Mexico
87061 United States
Phone: 919-596-2497

Seller's item number:

Seller's Terms of Sale:
We want your books to arrive in the same condition as when we packed them for you! So, we ship all books and journals in boxes, with plastic to protect against moisture and extra padding (bubblewrap, cardboard etc) to protect against books shifting during post office handling.

MasterCard ,Visa, AMEX accepted. Paypal, Checks (U.S. funds drawn on a U.S. bank) or Money Orders also welcome.

Books are returnable for a full refund if not as described, within 7 days after receipt; please contact us if you are unhappy with your purchase for any reason.

We will happily combine shipping on multiple books to one mailing address, to save you money. Libraries and institutions billed upon request. New Mexico residents will be charged appropriate sales tax.

All prices are in US dollars; books are generally shipped one to two business days after payment is processed. Sorry, no CODs

All books are subject to prior sale

TAX: New Mexico residents add 5.125% sales tax

PLEASE NOTE, there are only single copies of most books, although we do have some duplicates -- orders will be filled on a first-come, first-served basis.

Checks or money orders mail to:, P. O. Box 66, Torreon, NM 87061 USA
For those paying by money order or check, books will be held as a courtesy for 7 days to allow your payment to reach us. Please include the inventory number and author or title so we may be sure you are getting the correct book!

Shipping is additional -- U.S. shipping, media mail or priority, includes delivery confirmation, insurance is included at no charge for orders over $50.00; buyers may request insurance at any time. Extra charges may be quoted for oversized, sets, or very heavy books. International shipping- Priority Airmail Flatrate Medium or Large Box as appropriate. Questions? Please e-mail us!

Thank You!

Want to find more items on this subject? Click here.

To find more books from this dealer, Click here.

Home   Contact Us   Bookdealers   Browse Books   Detailed Search   Antiques Collectibles   Privacy Statement   Shopping Cart

Copyright © 2000 - 2016 TomFolio is a registered
trademark of ABookCoOp, Inc. All rights reserved. Legal Information.