=== Power Switch and Battery
In addition to the circuit board itself, EasyMotor needs
- a power switch and battery to operate. Unlike most other
- Altus Metrum products, EasyMotor does not work with
- single-cell LiPo batteries. That's because commonly
- available inexpensive pressure sensors need 5V, which is
- more than a single-cell LiPo provides. Any battery that
- provides from 6.5 to about 15 volts should work. Good
- choices are the common 9V alkaline battery, or the very
- small and light A23 12V alkaline batteries.
+ a power switch and battery to operate. Like many Altus
+ Metrum products, EasyMotor requires a single-cell LiPo
+ battery, and has an on-board charging circuit. The 5V
+ needed for inexpensive pressure sensors is generated
+ onboard using a switching regulator to boost the voltage.
Because he often mounts EasyMotor to the motor's forward
bulkhead instead of to the airframe itself, Bdale often
by the sensor. Very inexpensive sensors that have a
“1/8 NPT” threaded input, a “Buick-style” 3-pin connector,
and typically ship with a short cable and mating
- connector, are readily available on eBay and AliExpress.
+ connector, are readily available through various vendors
+ including Amazon, eBay, and AliExpress.
To log in-flight chamber pressure, a typical approach
might be to drill a 1/8" sampling hole all the way
NPT” pipe tap. Fill the touch hole with grease, screw in
the pressure sensor, and attach the sensor leads to
EasyMotor.
+
+ If you aren't up for machining closures yourself,
+ link:http://lokiresearch.com[Loki Research] sells
+ 54mm and 75mm "experimental bulkheads" with threaded
+ sensor ports that can be used with snap ring cases.