Wednesday, 4 January 2017

Dew Heater Controller - A bit further

I came home today after a trip to the post office (to send back the SMPSU) and a walk in the woods to photograph fungi (where I found a musket ball!), to a pile of packets on the doormat. These all contained various items for Arduino projects, including two more Nanos, and a barometric pressure sensor.

Most importantly, these packets also contained both the 'raw' TO92 DS18B20 temperature sensors, but also the housed and wired sensor. Which meant that if all was well I could crack on with the Dew Heater Controller.

First, I uploaded the 'Blink' test sketch to each of the new Nanos to make sure they worked. Both ok. I then rebuilt the Dew Heater Controller on the breadboard, and added one of the new DS18s - Yay! It works!

In the photo above, ive changed the sensor to the wired one, which luckily also works. You can see that now the controller can measure the 'lens' temperature (shown as 16°C) and also how much higher or lower this is than the dewpoint (in this case its 10°C above the dewpoint). The bargraph shows the percentage 'ON' time required by the heater strip. As this setup on the bench is well above the required Dewpoint + 5°C, there is no need for the heater to be on and so no indication on the bargraph. I have changed the temperatures a bit to make it think the heater is needed, and the bargraph does indeed change. You can also see that the display says 'Heater 1'. The code in this version is 3 channel.

Next step with this is to add the MOSFET driver and the heater band, and if all is well, proceed to boxing it up ready for use!

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