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Topic: DCDW vs DCSW Shootout (Read 4 times) previous topic - next topic


Sep 16, 2011, 04:10 am Last Edit: Oct 08, 2011, 03:48 pm by AltairLabs Reason: 1
Update on DCDW vs WickedNode:

The DCDW battery test is coming to an end, the DCDW node I started at end of April was down to 6v the last time I got home.  Will post graphs next time.

Here today is demonstration of the sensor resolution.  A 100k thermistor was used in both cases.  I prefer high resistance thermistors since they dissipate less power.  For WickedNode the 100k thermistor was put in a voltage divider with a 100k fixed resistor, chosen for best resolution.  For DCDW the 100k thermistor was combined with a 5000 pF capacitor to form the sensor oscillator in "swarm" mode which most closely matches the way WickedNode is usually employed.  For WickedNode this drains battery at 2.5 uA rate always, for DCDW thermistor dissipates power only during transmit.

OK the big difference we want to point out is temperature resolution.  An atrocious code hack was created to monitor both WickedNode and DCDW on a single receiver using RXD Arduino pin used by WickedNode.  No you dont wanna see the code its reeeaaaallllly nasty, but hey it works.

Here is the graph of room temperature where I stayed last night:

The DCDW curve (blue=upper=LH scale) shows clearly the room temperature during a night and day.  WickedNode curve (red=lower=RH scale) shows the same temperature changes from an identical sensor as coarse steps.  WickedNode is limited to its 8 bit resolution, whereas DCDW is counting a 3 kHz tone to a 1 Hz resolution, almost 12 bits.  Additional circuitry and software changes could help WickedNode at the cost of battery life and complexity, however DCDW achieves this naturally by design and simple component value selection.


Oct 02, 2011, 08:12 pm Last Edit: Oct 08, 2011, 03:49 pm by AltairLabs Reason: 1
DCDW battery life test almost at an end...  after 5 months!

DCDW was started with a Kroger generic brand 9v alkaline battery on April 28 2011.  As of October 2 the battery is still at 5.3 volts.  This DCDW node is configured for the transmit interval to depend on battery voltage.  Over 5 months the voltage (blue=RH scale, volts) decays from 9.5 to 5.3 volts as reporting interval (red=LH scale, seconds) rises from 10 minutes to 25 minutes.

No additional components are needed to monitor battery voltage, just one jumper wire was moved.

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