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Logic Function Indicator Probe

IP.com Disclosure Number: IPCOM000095160D
Original Publication Date: 1965-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 49K

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Related People

McDonald, JF: AUTHOR


A probe is provided with circuitry for detecting circuit logic conditions.

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Logic Function Indicator Probe

A probe is provided with circuitry for detecting circuit logic conditions.

Portable probe 1, either for hand held operation or inclusion in a machine, has flexible front probe 2, probe plug 3 for connection of external probe 4, indicator lamp 5, and three-position mode control switch 6.

Probe 1 contains all circuitry necessary for establishing an indication of various types of gating signals and pulses. The circuitry, middle drawing, includes indicator lamp 5 driven by indicator driver circuit 7. This is controlled, in turn, by multivibrator 8. The latter is triggered for a timed duration, such as 50 milliseconds, by And 9. This has three inputs including diodes D10... D12. D10 input is conditioned by input stage 13 that includes transistor T14.

The type of response of the circuit to various signals is established by movement of switch 6 to one of its three positions, lower drawing. In position 1, stage 13 supplies a logical 1 input to D10. The input to D12 is floating which is the same as a logical 1.

Thus, the output of gate 9 is dependent upon the input signal from either probe 2 or probe 4 to D11. Any positive pulse detected by either probe having a duration of a few nanoseconds or greater conditions gate 9 to trigger multivibrator 8. This then drives indicator block 7 and lamp 5 for the predetermined duration.

With switch 6 in position 2, the inputs to D11 and D12 are floating, thus corresponding to logical 1 inputs. The output...