Multi-function tester

• US 4,859,932 A
• Filed: 11/21/1988
• Issued: 08/22/1989
• Est. Priority Date: 11/21/1988
• Status: Expired due to Fees

• Current Assignee: William E. Whitley
• Original Assignee: William E. Whitley
• Inventors: Whitley, William E.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Mueller, Robert W.
• Application Number:
  US07/273,548
• Time in Patent Office: 274 Days
• Field of Search: 324/72.5, 324/72, 324/133, 324/543, 324/539, 324/540, 324/66, 324/555, 324/556, 324/500, 324/537, 340/652, 340/654, 379/26, 379/33
• US Class Current: 324/72.5
• CPC Class Codes: G01R 15/002 Switches for altering the measuring range or for multitesters
• CPC Class Codes: G01R 19/155 Indicating the presence of voltage
• CPC Class Codes: G01R 31/08 Locating faults in cables, transmission lines, or networks
• CPC Class Codes: G01R 31/54 Testing for continuity

Abstract

A multi-function tester (10) for testing electrical continuity and detecting the presence of various types of voltages comprises a bistable flip flop (14) having set and reset input terminals (2, 6) which are driven by voltage changes thereat to change the level of voltage appearing at an output terminal (3), with the set input terminal being coupled to a voltage source (12) through a set resistor (30) and being coupled to a common terminal (26) through a TMOS FET switch (16). An LED (32) is connected between the flip flop output terminal and the common terminal. A storage switch (18) couples and decouples the set and reset terminals. A voltage probe (20) coupled to the DC voltage source, a common probe (22), coupled to the common terminal, and a switch probe (24), coupled to a switching terminal (38) of the TMOS FET are used to place voltage signals on the switching terminal, both directly and through other circuits, for changing a switching impedance of the TMOS FET and thereby changing the voltage at the set and reset input terminals for changing the state of the flip flop and thereby activating and deactivating the LED.

Claims

1. A multi-function tester for testing for electrical continuity and the presence of various types of voltages comprising:

a DC voltage source for providing electrical DC-voltage;

a bistable flip flop circuit having a set input terminal, a reset input terminal, and an output terminal, said output terminal being switchable between a first output voltage-level state and a second output voltage-level state by application of respective voltage changes at said set and reset input terminals, said bistable flip flop circuit being coupled to said DC voltage source and powered thereby, said set input terminal also being coupled to a set voltage divider circuit extending between said DC voltage source and a common terminal, said set voltage divider circuit having a set fixed resistor therein;

an indicator means coupled between said output terminal and said common terminal for producing a detectable output when said first output voltage level appears at said output terminal;

a voltage steerable switch means coupled in said set voltage divider circuit for selectively immediately decreasing a switch impedance in response to a steering voltage of a first magnitude being applied to a switching terminal thereof and immediately increasing said switch impedance in response to a steering voltage of a second magnitude being applied to said switching terminal thereof to thereby change the voltage appearing at said set input terminal to move said flip flop between said first and second output voltage level state;

a voltage probe coupled to said voltage source;

a common probe coupled to said common terminal;

a switching probe coupled to said switching terminal;

wherein each of said voltage, common and switching probe can be selectively brought into contact with each other and can be brought into contact with electrical circuits to be tested;

whereby voltage signals from both said DC voltage source and from outside sources can be placed on said switching terminal with said voltage, common and switching probes, both directly and through other circuits, for immediately changing the voltage at said flip flop circuit set input terminal in a sense for causing said first level voltage to appear at said output terminal to thereby cause said indicator means to produce a detectable output and voltage signals can be removed from said switching terminal for immediately changing the voltage at said flip-flop circuit set input terminal in a sense for causing said second level voltage to appear at said output terminal to thereby extinguish said indicator means.

2. A multi-function tester as in claim 1 wherein, said voltage steerable switch is a TMOS field effect transistor.

3. A multi-function tester as in claim 1 wherein, is further included a storage switch between said set and reset input terminals for being opened and closed and wherein said bistable flip flop circuit responds to oppositely directed voltage changes at said set and reset input terminals for respectively switching said output terminal between said first and second output voltage levels, said second level output voltage level extinguishing said detectable output.

4. A multi-function tester as in claim 3 wherein, said voltage steerable switch is a TMOS field effect transistor.

5. A multi-function tester as in claim 3 wherein, is further included a voltage divider circuit between said switching probe and said common probe.

6. A multi-function tester as in claim 5 wherein, is further included a sensitivity switch in series with said voltage divider resistor positioned between said switching probe and common terminal.

7. A multi-function tester as in claim 6 wherein, said voltage steerable switch is a TMOS field effect transistor.

8. A multi-function tester as in claim 1 wherein, it is further included a voltage divider circuit between said switching probe and said common probe.

9. A multi-function tester as in claim 8 wherein, is further included a sensitivity switch in series with said voltage divider resistor positioned between said switching probe and common terminal.

10. A multi-function tester as in claim 8 wherein, said voltage steerable switch is a TMOS field effect transistor.

11. A multi-function tester as in claim 1 wherein, said indicator means is a light-emitting diode.