I’m working on a project that’s very small and not much space. It has one 6v servo, and I want to use one 9v battery to power the Arduino AND the servo, without needing to use a 9v AND a 6v pack. Is there any little module that can lower the voltage to a safe 6v for my servo? Or better yet, can I just power my nano+servo with one 6v battery pack?
Thanks.
You can 6V on Vin for the Nano but because of the servo you may need to add some extra electrolytic caps across the 5V and maybe even the Vin.
If the Nano is unreliable when the servo is running start by adding caps to Vin and then 5V, and increase incrementally starting at 47uF, (and then 100uF,220uF,330uF ,470uF....etc) as needed.
Is the mystery Nano Arduino a 5V device? If so you can use a 6V battery pack to power both, but 5he power to the Arduino must be less than 5.5V. Use one or two silicon diodes (1N400x) in series between the 6V positive and the 5V input of the Arduino to drop the voltage. Each diode will drop about 0.6V.
If the unnamed Nano Arduino is 3.3V, use a buck converter to drop the 6V to 3.3V.
The caps that raschemmel recommends may be necessary to filter motor noise from the supply to the Nano.
Although you've given no details I would be surprised if your servo wouldn't also work on 5V so that would be the way to go. I'd use 4 x 1.2V NiMH rechargeable batteries to the servo and the Nano's 5V pin (assuming it's a 5V Nano).
Steve
Small 9V batteries (PP3 size) are not upto powering motors and servos. You need at least 1A per servo to keep solid power rail voltage.
Its best to have separate power for Arduino and servos too, the Arduino power needs to be free from voltage spikes and drop-outs.
What servo?
I have sequentially powered six of these servos directly from Arduino Uno GPIO pins with no issues.
For background, this was for an Easter Egg hunt that I built a couple of years ago. As the players found an appropriate clue, an MQTT message is published that tells the egg box to drop a plastic egg containing more clues to the game..
SteveMann:
I have sequentially powered six of these servos directly from Arduino Uno GPIO pins with no issues.
Sorry but I don't believe that. The GPIO pins can supply no more than 40mA and the stall current of an SG90 is 650mA, running current around 100mA depending on load. The GPIO pins can and do CONTROL servos but they cannot power them.
Perhaps you mean powered from the Arduino 5V pin? That's still not a good idea but it will likely work for a small servo, at least for a while.
Steve
Sorry but I don't believe that.
Actually, I do, because if you read the application , there was almost no load on the servos.
They were NOT driving aerodynamic surfaces of a fixed wing aircraft flying at 40 mph. They were used for
some easter egg hunt :
that tells the egg box to drop a plastic egg containing more clues to the game..
How much of a load is that ? (practically nothing)
What you are NOT taking into account is that you can do a hell of a lot with 40mA in a gearbox .
The servo gearbox makes all the difference in the world.
If you run one of those servos off a 40mA digital output, you'll be surprised how much torque you can still get. And it actually doesn't matter how many he was running at the same time because the total current draw was less than the maximum for the arduino.
raschemmel:
You can 6V on Vin for the Nano but because of the servo you may need to add some extra electrolytic caps across the 5V and maybe even the Vin.
If the Nano is unreliable when the servo is running start by adding caps to Vin and then 5V, and increase incrementally starting at 47uF, (and then 100uF,220uF,330uF ,470uF....etc) as needed.
I'm still new to electronics, can you explain to me what electrolytic caps are and how I would set them up for my application?
Sorry for the late response to this thread
make sure to connect the "-" side of the caps to GND.
Electrolytic caps are ONLY MARKED AT THE "-" (NEGATIVE) TERMINAL.
raschemmel:
Actually, I do, because if you read the application , there was almost no load on the servos.
You're welcome to believe what you like but I've regularly measured SG90s taking short term currents of over 100mA on startup even with NO load, just sitting there without even a servo arm on.
So I'm not going to recommend powering them from a GPIO pin and I'm not even going to try testing it on my equipment because it don't want to damage a perfectly good Arduino. If you do test your theories please report back.
Steve
I would but I just gave away all my RC stuff (a month ago) to the guy who introduced me to RC back in 2005.