Go Down

Topic: How to power Arduino Nano that controls a robot arm with 6V power source (Read 352 times) previous topic - next topic

habanero

I've been working on a project that involves controlling a toy robotic arm called the OWI Robotic Arm Edge with an Arduino Nano. It took me a while to figure out what kind of motor controller circuitry to use to control each of its 5 motors. At first I tried 10 discrete BJT transistors, but that resulted in weak movement, if at all. I then tried 293D ICs, but they too resulted in underpowered motor output.

I finally settled on circuit boards based on the TB6612FNG chip, which allows the control of up to 2 motors up to around 1.2A each. I use 3 of them, using only one of the controllers on the 3rd board. It works quite well, giving full movement and power no different from what I'd get using the wired controller directly. I then added an nRF24L01+ board to the setup to allow me to control the arm remotely using the wired controller, connected to an Arduino Pro Mini, with its own nRF24L01+. Finally got that to work too, and it works quite well.

The thing is, I can't figure out how to power the Arduino Nano that controls the arm. The arm itself is powered by 4 x D batteries, yielding a total of ~6V, the positive end of which connects to each controller board's Vm (motor voltage) pin. When programming and testing the Nano, I of course power it via its mini-USB connector. I've also been able to power it with a 9V battery connected to the Nano's Vin (Raw) pin. But, I've been unable to successfully use the 6V provided by the 4xD batteries to power the Nano, so it won't need a second battery or power source.

At first I tried connecting the 6V to the Nano's Vin pin, but that led to very weak and inconsistent results with barely any arm movement. Then I tried a 7805 voltage regulator, with similar results. I also tried a switching buck converter, but, same results. But surely there's a way to use the 6V from the 4xD batteries, which provide more than enough current to power the whole setup, to power the Nano, controllers and nRF24L01+. I just can't figure out how. I suppose that I could try connecting the 6V to the Nano's 5V pin, but that might well fry it.

Any ideas on how to do this? There's got to be switching or regulator chips or circuits that do this, with relatively high efficiency. Suggestions?

slipstick

A DC-DC switching converter should work fine provided you choose the right type. You can either boost the 6V to about 7-8V and connect to Vin or drop it to 5V output and connect to the 5V pin. Either way works.

Steve

habanero

A DC-DC switching converter should work fine provided you choose the right type. You can either boost the 6V to about 7-8V and connect to Vin or drop it to 5V output and connect to the 5V pin. Either way works.

Steve
Thanks. The one I used didn't work, at least not well enough. Any types to recommend or features to look for? I'm hoping to keep costs down and the size small. Like, $2-$5 on eBay and no bigger than a Pro Micro.

Go Up