Pressure Sensor board

A project log for Pneumatic Tech for Prototyping

This page is a collection of tech that was developed during pneumatic projects and deserve a write-up of their own.

Nelson PhillipsNelson Phillips 03/27/2018 at 11:390 Comments

Air pressure sensor board was developed in the soft handy project after the 2016 hack-a-day prize as one of the issues was trying to prototype the mechanism of the robotic system and circuit hardware on a breadboard. A couple of gnarly attempts were made to integrate all the circuits onto a perf-board, but this was still a bit messy and it was easier to translate the schematic onto a gerber file and spend a little bit of money to give much cleaner results.

Second batch - less the mistakes
Second batch in "action"

Having received the first batch an opportunity arose to test this same sensor with a much higher gain value with an expensive low pressure sensor in a wind-tunnel. Being quite skeptical that it would work the results of the direct comparison with the expensive sensor and this cheap solution made it a real possibility.

The wind-tunnel test used a kiel probe with a silicon tube exiting the rear and connecting to the sensor. These probes measure the dynamic pressure of the air flow and act similar to a pitot tube but the static pressure is measure separately to give the total pressure which the air speed is able to be calculated. 

Kiel probe - 3D printed
CAD version
Section view of a kiel probe

my expectation was that there would be excessive noise and drift, but that was not the results so happy days.

The idea then was to accelerate the development of this sensor board for the purpose of sale on Tindie. So the next step was to find a ready supply of sensors and a instrument amplifier that was fit for purpose. Ideally these would be surface mount for ease of production and they tend to be less expensive.

There are a number of different sensors floating around the internet and there seems to be a steady supply of through hole sensors through secondary channel like ebay , aliexpress and banggood. Working with these they seem to be fine for use, but that's not a supply chain. So the MPS-3110 sensors ended up being the go to chip.

Finished product that was released on Tindie