Science Buddies: "Ask an Expert"

I'm working on the Drone Altitude Control Circuit and can't get the the Potentiometer (the blue rectangular part with a white knob) to work.

I've taken all the wires out of the breadboard and put all the pieces in the board according to the instructions. The motor turns on and the propellers all work.

The challenge is that I can't get the knob to work so that I can control the output of the battery power.

Any suggestions on how to get the knob to work?

https://www.sciencebuddies.org/stem-act ... de-control

Hi - can you please upload pictures of your breadboard using the "Attachments" feature below the main text box? We will need to see your circuit to figure out what's wrong. Please make sure the pictures are well-lit, in focus, and show the breadboard from a top-down view so we can clearly see all the connections. You may need to take more than one picture to clearly show everything.

Here's a photo, let me know if you can see this clearly.

Hi, two things:

1) In this picture it looks like your drone's wires are plugged directly into the breadboard's power buses. I assume you did that to test that the motors worked, is that correct? The potentiometer will have no effect in this configuration.

2) Your battery pack wires are reversed when going to the breadboard power buses. The red wire should go to the "+" bus and the black wire should go to the "-" bus. If you reverse that, and then move the green drone wire to the middle pin of the MOSFET, and make sure the short black jumper wire from the 3rd pin of the MOSFET is going to the "-" bus (I can't totally see where it's connected in your picture), then it should work.

Thanks for all the detailed help on this! Really appreciate that.

It works now

Will be a fun experiment.

No problem! If you haven't already, I highly recommend watching the video on our "how to use a breadboard" page. Understanding how a breadboard works internally can help immensely when debugging projects like this: https://www.sciencebuddies.org/science- ... breadboard

Thanks for that. I'll check out that link on breadboards.

In the meantime, I was able to get the power to work and control the amount of power. The propellers spin and are set up correctly (eg the two clock wise are opposite each other and the two counter clockwise are opposite each other.)

Unfortunately the drone is not lifting off and flying.

Any ideas why? Or can you point me to some tips on this?

Hi - the biggest problems we've seen with this are the drone being too heavy and the guide rails/straws not being parallel. You should be able to easily slide the drone up the dowels by hand, let go, and it should fall back to the bottom. If it's hard to slide or gets stuck on the way down, then there is too much friction between the straws/dowels and they may be improperly spaced or misaligned. If you used an excessive amount of tape or glue to build the drone then it might be too heavy. This project can also drain the batteries pretty quickly, so if you've been running it for a while, you might want to try fresh batteries. Finally, I know you said the propellers are on the right way, but to be 100% sure the propellers are on the right way *and* the motors are wired correctly, make sure you feel air blowing *down* from each motor when you hold your hand *under* the drone.