I recently purchased an Arduino Pro Mini 5V. What is the best way to power it untethered? The RAW pin is a buck converter from 5-12V to regulated 5V, so can I hook up 4 AAs or a 9v battery to that? And will the buck converter isolate my voltages if I use that same 6 or 9 volts to power my Servos and motors?
What I'm doing with it is making a UAV Bicopter (Think the Avatar gunship or a V-22 Osprey). Feeback Input will be a Memsic2125 accelerometer running off 5V (I believe that's VCC on the Pro Mini? Or should it have isolated power?). Output will be 4 PWM signals, two to the servos (either Parallax Continuous Rotation or some other ones) and two to the transistors driving the 9v motors for the rotors.
Personally I'd go for a multi-cell pack (even if it's just 4-6 AA batteries.) A single 9V doesn't produce anywhere near enough Amps compared to 4x AA batteries. You may find that you're vehicle dies rather fast.
Right, the issue here is the weight. Maybe I can get an RC battery or something.
I just purchased propellers for my motors and am doing thrust tests and I am not impressed. The motor can barely lift itself up under the full 9V. Though I feel this is a topic for another part of the forum, aerodynamics and power stuff. I'll post somewhere else.
Does the buck converter on the Pro Mini isolate the current drawn from the battery? So if I hook a 9v power supply to the rotors and Pro Mini raw pin, will there be much noise? A cap and/or diode across the motors can probably eliminate some of it.
dgonz:
I recently purchased an Arduino Pro Mini 5V. What is the best way to power it untethered? The RAW pin is a buck converter from 5-12V to regulated 5V, so can I hook up 4 AAs or a 9v battery to that? And will the buck converter isolate my voltages if I use that same 6 or 9 volts to power my Servos and motors?
You seem to confuse buck regulator with linear regulator - Arduinos have linear regulators and will only work when the input voltage is higher than 5V by a sufficient margin, perhaps a volt or more (depends on the regulator)
A buck converter is a switch-mode regulator that needs an inductor to convert more efficiently - but with more complexity and more power rail noise (bad news if using analog inputs)
You should almost certainly use a separate supply for the motors, because when the motor stalls the voltage will drop enough to reset the Arduino - be warned. Alternatively you can add more decoupling on the Arduino supply as a stop-gap solution.
Promini will run just fine with 4.5V from 3 AAs going into the VCC pin, bypassing the onboard regulator.
I have 14 of them running that way at my fencing club.
I have another running at 8MHz with 1000mAH LiPo battery powering the VCC pin. That could be another option for weight savings.
