Let's Make Robots!

Created: Forum topic

Electromagnet Calculations

Hey guys, I think I really just need some help with Google search terms here...

I am making a solenoid, or more specifically, the coil part. I need to find an online calculator or some equations to figure out the proper gauge and number of wraps to give me a given resistance and/or strength. I am sure they are out there but for the life of me, I can not seem to put together the proper set of Google search terms to get me to where I need to be. I have been googling for over an hour now finding nothing of any use.

LMR/ HTML/ iFrame not playing nice

Hey guys, I am trying to embed a Google Docs (Google Drive) Presentation in a LMR post. I can paste the html into the HTML pop-up window, but after hitting "update" nothing happens and my html code is missing if I reopen the HTML editor.

I can get the iFrame to work via disabling rich-text, but again, it is nowhere to be found (also, again, the html code disappears) if I save or otherwise update the post.

I will post the code below, I am not sure how this post will handle it. 

Binary Number directly from Arduino I/O pins?

Hey guys, I know there has got to be a way to do this, but I can't seem to find it at the Arduino reference page and I don't seem to be using the correct google terms.

I have a 4-bit parallel output from a chip going to 4 digital input pins on an arduino. The chip I am using is putting out a nibble of 4 bits representing a number in binary form. I need the arduino to read the state of these 4 pins and give me a number. I have done this via Picaxe in the past, but I can't seem to find the same thing in Arduino.

Rocket Brand Studios 48 hour thing... Links now available

Hey guys, 

Rocket Brand Studios will be participating in Deconstruction 2013. (woo hoo!)

Starting Friday afternoon (2.22.13), I will start building...   ...something. 48 hours later I will be dead --or-- have something really cool built. --And it is all going to be live streamed!


You will be able to watch everything on the front page at

Rocket Brand Studios

Need Sumo built (as a gig)

Hey guys,

I have a customer in Italy that I have done a bunch of custom robots for. He recently has requested a sumo bot --a couple/few of them actually, coded and ready to go. Just like a toy from a toy store, but with wires showing. 

This is a real gig, and I will happily pass it on to whomever wants it and there will be a fair bit of change at the end. 

AC Motor Speed Control Triac PWM 0-cross

Hey guys, I am working on the CNC and putting together a speed control system. I went as far as buying a $20 "Router speed controller" which consists of a pot and a BTA41-600B triac basically. The control is terrible and "hiccups" at anything less than 1/2 speed or so.

Obviously, an Arduino would seem to fit in here. I did the googling and I think I am down to one sticky wicket.

Are you using anything from Rocket Brand Studios?

Hey guys, I am putting together some pics, videos etc of customer's projects using stuff from the shop.

If you have used anything from Rocket Brand Studios in one of your projects, I would be your very best friend if you would be so kind to drop me a link here.

No need to do anything else, I will take care of the cutting a pasting --Just the links would be super great.


Thanks guys.


Cheap RX/TX via Fake X-bee? (X-bee footprint devices)

Hello, hello.

I am looking for a new, cheaper RX/TX system to carry. I would love it if I could find a cheap, solid device that shares the footprint and pinout of an X-bee. There are a few out there that I have found, but I cannot find any review etc. to help me determine if they are crap or not.

Does anyone use such a device? What is it and do you like it?


...And if we forget about the X-bee footprint/pinout issue for a sec, are there any RX/TX systems that folks are using that they particularly like?

Help finding cheap bulk X-bee headers

Hey guys, I am really stumped on this one.

I am running low on x-bee headers -- 1x10, 2mm pitch, female. I have done eBay and all the "hot spots" (jameco, goldmine, etc) and can't find these darn things! I have gone through all my email as well as hard-copy invoices and I can't even figure out where I got them the last time. 

I can, of course, find them at retail ($.90 to $1.00 /unit) but I can't seem to find them anywhere in bulk. I want to buy at least a 1000 and they should work out to < $.15/unit --Probably closer to $.05 /unit or so.

How To: Arduino to Parallax Serial Terminal

Well folks, I finally got around to doing this...