Pulse monitor circuit for use as a fan speed monitor
AssigneeGTE Automatic Electric Inc.
InventorDavid P. Giammarrusco
Life of this patent
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Abstract
A circuit which monitors air flow by comparing the speed of a fan to a predetermined frequency. A Hall effect device detects magnetic pulses representative of the fan speed and provides a corresponding electrical signal. This signal is compared with a predetermined threshold frequency by a retriggerable monostable multivibrator. A digital delay circuit isolates pace conditions and a relay circuit provides an indication of the fan speed status.
Claims13
A magnetic pulse monitor circuit for use in a system which includes a source of periodic magnetic flux signals, said magnetic pulse monitor circuit comprising:
- magnetic flux sensing means which is connected in magnetic flux proximity to said source of periodic magnetic flux signals and its operative in response to said periodic magnetic flux signals to provide corresponding periodic magnetic flux detection signals;
- detection means which is connected to said magnetic flux sensing means and is operative in response to periodic magnetic flux detection signals having a frequency greater than or equal to a predetermined frequency to provide a first frequency detection signal, and which is operative in response to periodic magnetic flux detection signals having a frequency less than said predetermined frequency to provide a second frequency detection signal;
- storage means which is connected to said detection means and said magnetic flux sensing means and is operative in response to said first frequency detection signal and a magnetic flux detection signal to provide a first storage signal, and which is operative in response to said second frequency detection signal to provide a second storage signal;
- and
- signalling means which is connected to said storage means and is operative in response to said first storage signal to provide a status signal of a first characteristic, and which is operative in response to said second storage signal to provide a status signal of a second characteristic.
A pulse monitor circuit for use in a system which includes a source of periodic pulse signals, said pulse monitor circuit comprising:
- detection means which is connected to said source of periodic pulse signals and is operative in response to said periodic pulse signals having a frequency greater than or equal to a predetermined frequency to provide a first frequency detection signal, and which is operative in response to said periodic pulse signals having a frequency below said predetermined frequency to provide a second frequency detection signal;
- storage means which is connected to said detection means and said magnetic flux sensing means and is operative in response to said first frequency detection signal and a magnetic flux detection signal to provide a first storage signal, and which is operative in response to said second frequency detection signal to provide a second storage signal;
- and
- signalling means which is connected to said storage means and is operative in response to said first storage signal to provide a status signal of a first characteristic, and which is operative in response to said second storage signal to provide a status signal of a second characteristic.
Dependencies are inferred from the claim text.