Introduction: Waving Pumpkin Halloween Robot
It is Halloween! So, I made a Halloween special :)
Just a pumpkin, but it has LED lights, and arms too, and yes, they are moving! Battery operated (no cables), so feel free to take it out on a party or just leave it in front of your house. It is a last-minute idea and it turned out way funnier than I expected. Please share yours if you make it. I wanna see :D
You will need a Pumpkin, some basic tools and:
-2x Servo motor (I suggest standard size): https://hobbyking.com/en_us/hxt-5010-twin-bearing...
-Servo tester: https://hobbyking.com/en_us/turnigy-servo-tester....
-Battery 1: https://hobbyking.com/en_us/zippy-compact-1100mah...
-Battery 2: https://hobbyking.com/en_us/turnigy-nano-tech-220...
-some LED light strip. Can be single color or RGB, with controller, or directly connected to the battery.
Not needed, but highly recommended:
-Low voltage alarm for both batteries: Buzzer
Step 1: Shape It, Stab It
This step is easy. Stab the pumpkin and take its brains out! Same way you do every Halloween.
Shape it spooky, funny, or whatever style you like.
As you can see in the video I googled pumpkin shapes and copied a simple one, as I was out of ideas :D
Step 2: LED Lights
I used about 2x 20cm RGB 12V LED strip since I had it at home. I also had a LED strip controller, so I can set up different functions of color change, blinking,... At the end, I just ended up setting a nice red/orange static color and I think it's the best, so If you use single color led strip without controller it is also going to do the job. It all depends how fancy do you want ti to be.
Power the LED's with a 3S LiPo battery. I had a 2200mAh pack already at home, but it can also be more/less capacity.
What is important here is not to drain the battery as you will permanently damage it.
There are 2 options to prevent this. I measured the current that the LED's consume. It was less than 200mA. This means they will last max 10h. Better less to be on the safe side. If you change every 8h you shall be safe, but if you forget you may damage them.
Better, to add a BMS, or a beeper that will make a sound when the cells are empty. RC beepers are loud, so you should have no problem to hear it if you do not put it outside far away from the house. There is a link of a recommended one in the first step.
Step 3: Robot Arm Motors
For the robotic arms, you need 2 servo motors. Standard size is the best, since they are the most robust and can handle heavy arms, but any servo can be used for this.
Mini or micro will also do the job, but you will need to use lightweight arms.
The easiest way to control them is with a servo tester, as many have an "automatic" function that swipe them form one side position to the other. If you mount them mirrored, one arm will go up and the other down. If you want both arms going the same direction mount them the way they will turn in the same direction.
This system needs about 5V to work. You can connect an UBEC (voltage step down regulator) on the same 3S LiPo battery for LED's or use a separate battery. This one can be a LiFe 6.6V, as most servos are ok up to 7V.
Again! Don't forget to protect it with a low voltage buzzer, or change it in time. I did not expect that, but those 2 servos actually consumed about 200mA at 6.6V in my case, and that is (because of a smaller battery in my case - 1100mAh) more than the LED's, so they needed to be changed more often.
Step 4: Arms
I wanted them to be natural, so I used tree branches. I created 4 types. Just connected them to the servo arms with cable ties and they were ready to go and easily exchangeable.
-Spooky (dead dry branches)
-Halloween (autumn colors with half dead leaves)
-Bush (acorn branches)
-Subscribe (special for YT video, sticker on a 3mm plywood)
Step 5: Packing
Put all this equipment in the pumpkin and it is ready to go. Because I did now want the electronics to be visible threw the pumpkin's face, I added some thin white foam, to make the lights a bit dispersed, and the equipment a bit hidden. It worked very well. There is more than enough space in the pumpkin even if mine was not that big. And yes, the led controller could be smaller, they exist, but I just had this big one on hand.
Step 6: Done
It is done!
Put it outside, have it in house, take it for a walk, go party with this pumpkin. It is wireless, wo free to go anywhere. Just don't forget to take care of the batteries so you don't drain them too much.
Thanks for your time and feel free to like, comment, subscribe. I will be happy to answer any comment.
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