Re: [Amps]8877 blower requirement...TXN ! ÂNow..Airflow sensing ?

[Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>]

One simple method is a small fan, free to rotate in the air stream. An LED- 
opto transistor arrangement then gives a series of pulses when the fan is 
arranged to interrupt the light beam, and a re-triggerable monostable - 74123 - 
gives a logic ouput that reverses when the air and fan stop. A bit of friction 
on the fan spindle and itr can detect low velocity air, too. Probably easier 
than a sensitive microswitch and an air bleed of one sort or another.
73
Peter G3RZP.
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