SEMICONDUCTOR TESTER HAVING VISUAL AND AUDIBLE DISPLAY

• US 3,689,838 A
• Filed: 06/07/1971
• Issued: 09/05/1972
• Est. Priority Date: 06/07/1971
• Status: Expired due to Term

• Current Assignee: Milton E. Thurman, 721 W. 11th St. Jr.
• Original Assignee: Milton E. Thurman, 721 W. 11th St. Jr.
• Inventors: Milton E. Thurman, 721 W. 11th St. Jr.
• Primary Examiner(s): Rudolph V. Rolinec
• Assistant Examiner(s): Ernest F. Karlsen
• Application Number:
  US05/150,368
• Time in Patent Office: 456 Days
• Field of Search: 324/158T,158D,158R,73R
• US Class Current: 324/762.08
• CPC Class Codes: G01R 31/2607 Circuits therefor G01R31/2642 takes precedence
• CPC Class Codes: G01R 31/2608 for testing bipolar transistors
• CPC Class Codes: G01R 31/2632 for testing diodes

Abstract

A semiconductor tester having a visual display including four information indicator lamps arranged in square with green lamps at adjacent corners and red lamps at the remaining corners and having an amber mode indicator lamp at the center of the square, is provided with a circuit producing an audible signal if the results of tests of the junctions of a bipolar transistor in two different test modes are that the junctions are conductive in the proper direction and are not short circuited, and also producing such audible signal if the results of the test of a diode in a single mode test is that the diode is conductive in one direction only. The information indicator lights provide additional information such as whether a good transistor is PNP or NPN, or that a good diode is improperly marked or improperly installed in the tester. In the case of a bad transistor the indicator lamps indicate the type and location of the fault present in the transistor.

Claims

1. A testing device for polar transistors which comprises:

first test means for providing separate first mode tests of the conductive properties of the emitter-base junction of said transistor and of the base-collector junction of said transistor;

second test means for providing a second mode test of the conductive properties of said transistor between the emitter and collector of said transistor;

control means for causing operation of said test means to produce a series of successive tests in which said first mode tests alternate with said second mode tests; and

audible signal means for producing an audible signal only when said junctions have forward conductivity and no substantial reverse conductivity during said first mode tests and said transistor has no substantial conductivity in either direction between said emitter and collector during said second mode tests.

2. The testing device of claim 1 in which:

said test means includes means for aPplying an alternating test voltage across said junctions to produce test signals when current flows through said junctions in either direction in said first mode tests and for applying an alternating voltage between said emitter and collector to produce similar test signals in said second mode test; and

said audible means includes means for producing said audible signal when test signals are produced by flow of current in a forward direction through said junctions during said first mode test and no other test signals are produced during said test.

3. The testing device of claim 2 which also includes storage means for storing said test signals from both said tests;

and said audible means includes logic means for determining when the test signals stored in said storage means are those produced by current flow in a forward direction during said first mode test and do not include any other test signals; and

means for delaying the production of said audible means until after any test signals produced in either of said test modes are stored in said storage means.

4. The testing device of claim 2 in which;

said audible means also includes means for producing said audible signal when said test signals produced during said first test mode are produced by current flow in a forward direction through the junctions of either a PNP or an NPN transistor.

5. The testing device of claim 2 in which;

said second test means includes means for applying an alternating test voltage between said emitter and said collector of lower peak to peak value than the alternating test voltage applied across said junction by said first test means.

6. The testing device of claim 2 which also includes;

diode testing means for testing diodes including means for producing test signals when the diode being tested has forward conductivity and is not short-circuited which are the same as the test signals produced by flow of current in a forward direction through said junctions of a transistor being tested by said first test means so as to cause production of said audible signal by said audible signal means.

7. The testing device of claim 2 in which;

said first test means includes means for producing a first pair of test signals when current flows in a forward direction through the junctions of a PNP transistor and a different pair of test signals when current flows in a forward direction through the junctions of an NPN transistor; and

said audible means includes means for producing said audible signal when either of said pairs of test signals are produced by said first test means and no other test signals are produced by either of said test means.

8. The testing device of claim 7 which also includes;

diode testing means for testing diodes including means for producing test signals which are the same as one of said pairs of test signals and no other test signals when said diode is conducting in a forward direction and not short-circuited.

9. The testing device of claim 8 which also includes;

function switching means for enabling said testing device to test said diodes when said function switch is in one position and enabling said testing device to test said transistors when said function switch is in another position.