Fan operating status sensing circuit
First Claim
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1. A method for sensing fan operating status using a current monitoring circuit, said method comprising the steps of:
- (a) monitoring current flowing through a direct current fan and producing a first signal proportional to the magnitude of said current;
(b) amplifying said first signal to create a second signal;
(c) filtering and clipping said second signal to remove direct current components and to create current pulses;
(d) detecting the presence of said current pulses;
(e) discharging a voltage storage means in response to the presence of said current pulses; and
,(f) comparing the voltage level of said voltage storage means to a voltage reference, thereby creating a third signal, said third signal providing an indication of the operating status of said fan.
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Abstract
A direct current fan'"'"'s status is monitored electronically using a current monitoring circuit. Normally, when a fan is running it exhibits a pulsating current input. The resulting alternating current signal is monitored via the current monitoring circuit to detect whether the fan is running or not.
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Citations
11 Claims
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1. A method for sensing fan operating status using a current monitoring circuit, said method comprising the steps of:
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(a) monitoring current flowing through a direct current fan and producing a first signal proportional to the magnitude of said current; (b) amplifying said first signal to create a second signal; (c) filtering and clipping said second signal to remove direct current components and to create current pulses; (d) detecting the presence of said current pulses; (e) discharging a voltage storage means in response to the presence of said current pulses; and
,(f) comparing the voltage level of said voltage storage means to a voltage reference, thereby creating a third signal, said third signal providing an indication of the operating status of said fan. - View Dependent Claims (2)
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3. An apparatus comprising:
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a direct current fan; and a circuit for sensing the operating status of said fan by current monitoring, said circuit comprising; a first resistor connected in series with said fan; an amplifier means connected to said resistor; a filter means responsive to said amplifier means; a clipping means connected to said filter means; a trigger means, responsive to said filter means and said clipping means, for discharging a voltage storage means; and a comparison means for comparing the voltage levels of said voltage storage means and a voltage reference wherein said comparison means generates an indication of the operating status of said fan. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10)
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11. A method of monitoring the operation of a direct current fan comprising the steps of:
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monitoring a direct current supplied to the fan; detecting a pulsating current component of the direct current; and providing an indication of the operation of the fan in dependence upon a magnitude of the detected pulsating current component.
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Specification