555 breath monitor circuit

Published:2011/5/23 20:04:00 Author:TaoXi | Keyword: breath, monitor | From:SeekIC

As the figure 16-12 shows, the monostable trigger is composed of the 555 time base circuit, and this circuit connects with a external transistor, the lost pulse detection circuit is composed of the external transistor and the monostable trigger. S1 is the air switch. When this circuit is used in the patient's breath monitor application, if the interval of the two respiratories overs the pre-set time, this circuit sends out the alarm signal to remind the health care workers or guards. When the breath is normal, the air switch S1 opens and closes with the breath, R2 is set in the longest time of the twice reset pulse, if it is not resetting in a given period of time, 555 will output the low electrical level.



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