SIMULTANEOUS MULTI-CORE DEMAGNETIZATION

• US 3,859,573 A
• Filed: 10/01/1973
• Issued: 01/07/1975
• Est. Priority Date: 10/01/1973
• Status: Expired due to Term

• Current Assignee: Western Atlas International Incorporated (Northrop Grumman Corporation)
• Original Assignee: Ben B. Thigpen, Charles C. Harman, Lee E. Siems
• Inventors: Siems, Lee E., Thigpen, Ben B., Harman, Charles C.
• Primary Examiner(s): Hix, L. T.
• Application Number:
  US05/402,639
• Time in Patent Office: 463 Days
• Field of Search: 317/157.5
• US Class Current: 361/149
• CPC Class Codes: H01F 13/00 Apparatus or processes for magnetising or demagnetising devices for holding workpieces using magnetic or electric force acting directly on the workpieces B23Q3/15 ; for degaussing ships B63G9/06; for clocks or watches G04D9/00; recording or erasing of information on magnetic record carriers G11B5/00 ; demagnetising arrangements for colour television H04N9/29

Abstract

This invention relates to demagnetizing the cores of a plurality of input transformers, each transformer having a primary winding and a secondary winding connected to a load subject to becoming non-linear. The load has a linear operating mode when the amplitude of a sinusoidal signal applied to the primary winding is below a critical value and a non-linear operating mode when the amplitude of the applied AC signal exceeds this critical value. The demagnetization is achieved by '"'"''"'"''"'"''"'"'wiping'"'"''"'"''"'"''"'"' each transformer core with a decaying AC signal having an initial amplitude up to the critical value and a frequency corresponding to the initial amplitude which is sufficient to saturate each core.

Claims

1. In a method for demagnetizing the cores of a plurality of input transformers, each transformer having a core, a primary winding and secondary winding connected to a load, the load having a linear operating mode when the amplitude of an AC signal applied to the primary winding of the load'"'"''"'"'s input transformer is below a critical value, and the load having a non-linear operating mode when the amplitude of the applied AC signal exceeds said critical value, the improvement comprising:

wiping each core with a decaying AC signal having an initial amplitude up to said critical value and a frequency corresponding to said critical value, the value of said frequency being selected to saturate each core.

2. The method of claim 2 wherein the cores of said plurality of transformers are wiped simultaneously.

3. The method of claim 3 wherein said load is a preamplifier.

4. A method for demagnetizing an input transformer having a core, a primary winding and a secondary winding connected to a load, the load having a linear operating mode when the amplitude of an AC signal applied to the primary winding of the load'"'"''"'"'s input transformer is below a critical value, and the load having a non-linear operating mode when the amplitude of the applied AC signal exceeds said critical value, the improvement comprising:

wiping said core with a decaying AC signal having an initial amplitude up to said critical value and a frequency corresponding to said critical value, the value of said frequency being selected to saturate each core.