Circuit Project Electronic

A sensitive and reliable way to measure airflow is to exploit the predictable relationship between airspeed and the heat dissipated by a sensor exposed to the flow while being held at a constant temperature differential above ambient. The power required to maintain the elevated sensor temperature is proportional to the square root of the airspeed (King’s law). The popular hot-wire anemometer uses this principle, but suffers from the disadvantage of using a relatively fragile airflow sensor, a thin metallic filament.

Read more original source:http://www.edn.com/archives/1996/031496/06di3.htm

Stabilized Power Supply 5V,6V,9V,12V and 18V With Short Circuit Protection by IC 7805 , 7806, 7809,7812
Here is an efficient 4-stage stabilized power supply unit for testing electronic circuits. It provides well regulated and stabilized output, which is essential for most electronic circuits to give proper results. The circuit provides an audio- visual indication if there is a short circuit in the PCB under test, so the power supply to the circuit ‘under test’ can be cut-off immediately to save the valuable components from damage.

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A previous Design Idea presented a simple flow-to-frequency transducer that easily fits into mP-based measurement systems (Reference 1). You can accumulate and linearize its frequency output by using software without the need for ancillary circuitry. In other applications, however, you might prefer a linearized analog output.

Read more original source:http://www.edn.com/archives/1996/092696/20di4.htm