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Steve's Apparatus Design Company
Tube Tester Collection
Apparatus Design Company of Little Rock Arkansas

Welcome to my Apparatus Design Company collection. This site contains photos, manuals, and information about vacuum tube testers manufactured by the Apparatus Design Company of Little Rock Arkansas in the 1930's.

The Apparatus Design Company was founded in the early 1930's by Jewell R. Williams after he left Supreme Instruments.

Jewell R. Williams

The Apparatus Design Co. (ADC) manufactured several models including the "Confidence" series tube testers, "ADCO" tube tester, and the "ABC Unameter" below.

Please note:
The data and files contained here are items I have collected from many vintage sources. There is no guarantee of the accuracy of any information contained on this page. It is solely up to the end user to decide that the information and files contained here are accurate and fit for use with their equipment. I am not responsible for any loss or damages that may be incurred from the use of this information.

Adobe PDF Some files on this site are in Adobe PDF format. You need Adobe Reader to view Adobe PDF files. Download it here (free).    When viewing larger photos, you can use your browsers back button to return to the previous page.

ADCO Tube Tester ADCO Tube Tester
This small 3 socket tube tester selected tube settings with a series of short jumpers. The left dial sets the line voltage.
Case measures only 6½"x13"x5½"
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Confidence Special Tube Tester The Confidence Special Tube Tester
This unique tube tester had one selector with 56 settings. The data sheet lists the tube socket to use and a number to set the center dial to for the vacuum tube to be tested.

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Confidence Special #6 Data Sheet
Confidence Special #7 Data Sheet
1932 advertisment

Confidence Automatic B Tube Tester The Confidence Automatic Model B Tube Tester
This tube tester was also designed with one selector with 56 settings. This unit has the optional panel in the cover with an additional 10 tube sockets. Individual adapters were also available.

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Front Panel
Name Plate

Confidence B #4 Tube Data Sheet & Instructions
Tube data update for Models B & C #126
Adapter list and note Models B & C

Confidence Model 36 The Confidence Model 36 Tube Tester
Physically the largest of all the testers here, this Confidence Model 36, has one large tube selector in the center, and several controls and selectors for measuring DC volts, testing vibrators, and testing condensers.
The case measures 11½" wide x 18¼" tall x 6½" deep
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Confidence Model 36 Manual and Tube Data

Confidence Master Tube Tester The Confidence Master Tube Tester
The Confidence Master, has four long slide selectors. The far right adjusts the tester for the AC line voltage and the other three are set for the tube under test using the chart in the cover.
This is a AC powered tester and has the early Edison lamp socket connection instead of a two prong plug.
Photo 1
Photo 2

Confidence Master Instructions and Tube Data

ABC Unameter Tube Tester The ABC Unameter Tube Tester
Another unique tube tester.
Unlike the Confidance testers above that have one or more dial selecters, this Apparatus Design Co. tube tester like the Confidance Master, has four long slide selectors. The far right adjusts the tester for the AC line voltage and the other three are set for the tube under test using the chart in the cover.
The case is long compaired to the width of the tester and measures 17½" x 9¾" x 5½"
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Download: ABC Instructions and Data Sheet

Confidence Royal Tube Tester The Confidence Royal Tube Tester
This Apparatus Design Co. tube tester like the Confidence Master and the ABC Unameter, has three long slide selectors.
This might be the latest ADC tester in my collection as the faceplate and data sheet lists the Apparatus Design Company as a Chicago U.S.A. location, not Little Rock Arkansas.
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Face Photo
Download: Royal Instructions and Data Sheet

Confidence Bridgohmeter Confidence Bridgohmeter

Unlike most multi-meters today, this unique ohm meter by the Apparatus Design Co. uses a "null" meter for measureing resistance.
When the dials are set to the correct value, the meter pointer is in the null position. You then read the value off the dials, not the meter.
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Larger Photo (front panel)
Bridgohmeter Instructions and Data Sheet

Apparatus Design Company Catalog Apparatus Design Company
Burton Webber
Four Page Catalog

View Catalog

Confidence Tube Tester Schematic Confidence Tube Tester Schematic

View Schematic (PDF File)

More Apparatus Design Company items
posted as I acquire them.
If you have any ADC or ADCO tube testers, data sheets, manuals,
catalogs, or schematics for sale that are not listed here please contact me.


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