Claims
- 1. In combination with a user device and a current supply device, each device having at least two terminal connections and a ground connection, one of the terminal connections of the current supply device being connected to its ground connection, one of the terminal connections of the user device being connected to its ground connection, the other terminal connection of the user device being connected to a load element in the user device, a diode means in series with said load element between said other terminal of said user device and said load element; said load element also being connected to the ground connected terminal connection, of the user device said two terminal connections of both devices being engageable to produce a current flow, and a safety device within the user device connected between the ground connected terminal connection of the user device and the ground connection of the user device whereby during correct polarization of said user device, no current flows through said safety device, and during incorrect polarization of said user device said safety device operates to isolate said user device ground connection from said ground connected terminal connection.
- 2. The combination as defined in claim 1, wherein the user device includes a housing to which the user device ground connection is connected.
- 3. The combination as defined in claim 1, wherein the safety device is formed as part of a printed circuit board including a conducting path.
- 4. The combination as defined in claim 3, wherein the safety device is formed as a decreased cross section of the conducting path.
- 5. The combination as defined in claim 3, wherein the safety device is formed as a decreased cross sectional portion of the conducting path of a thick layer circuit.
- 6. The combination as define in claim 3, wherein the safety device is formed as a decreased cross sectional portion of the conducting path of a thin layer circuit.
- 7. The combination as defined in claim 1, wherein the user device includes a thick layer circuit board, and wherein the safety device is formed as part of the thick layer circuit board.
- 8. The combination as defined in claim 1, wherein the user device includes a thin layer circuit board, and wherein the safety device is formed as part of the thin layer circuit board.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2703255 |
Jan 1977 |
DEX |
|
2748267 |
Oct 1977 |
DEX |
|
Parent Case Info
This is a continuation of application Ser. No. 872,139, filed Jan. 25, 1978, and now abandoned.
US Referenced Citations (9)
Continuations (1)
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Number |
Date |
Country |
Parent |
872139 |
Jan 1978 |
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