[Amps] 8877 blower requirement...TXN ! Now..Airflow sensing ?

[Peter Voelpel]

What an effort instead using a simple microswitch in the airflow path
There is nothing as simple and reliable as that.

73
Peter 

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Peter Chadwick

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.