Governance by those who do the work.

Saturday, November 8, 2014

Convection Measurement Electronics

Pictured are two electronics boards constructed for measuring convection from an instrumented plate.  The small board on the left will measure pressure, humidity, and temperature of the air at the wind-tunnel intake.

The larger board contains power supplies, heater control and drive, signal conditioning, a three-digit 7-segment display, and a STMicroelectronics ARM STM32F3 Discovery board.  The ARM computer is the green board.  It will control the heater embedded in the plate and collect the sensor data during experiment runs.

The two yellow blocks connected by black cables to the larger board are receptacles for Lenovo laptop 20 Volt power supplies.  The large black object is a heat sink for the heater drive.

The other photo shows the wiring on the back of this board.  Although there are many soldered connections, most of the components are mounted on 16-pin DIP headers seen on the front side.  These are plugged into prototyping sockets with insulation-displacement contacts.  Connections made using 30 AWG wirewrap wire.  This technology was sold by 3M in the 1990s.  I don't think it is sold commercially any more.


faried nawaz said...

I hadn't thought about using laptop power supplies for such devices until reading this post! I can get them for cheap, and they produce clean DC current. It seems like they'd work great for boards that needs more power than a MicroUSB phone charger can put out.

faried nawaz said...
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