Let's Make Robots!

Wireless Controller advice

I have an arduino board and a picaxe board.  I'm looking to dabble into some wireless stuff but im not sure which way to go and what i need.  What would you guys reccomend for me to get as my first wireless contorller system?

Also not sure yet what project im going to use it for just brainstorming now.

Test email service

testing the emain notifications

Miller solar engine

I am currently building a solar roller using a miller style solar engine. If I let the capacitor charge then attach the motor to the circiut everything works fine. But if the motor is attached it does not work. I was wondering if I had connected something wrong or if I have to disconnect the motor to let it charge? I hope this makes sense. Thank you for your help.



Trying to encapsulate a servo instance, no movement

Hi there,

I'm having an issue with encapsulating servo functionality in its own class. What I want to do is creating a class that contains a couple of methods that control a servo more or less autonomously, in such a way that just requires me to set the context and then in the loop calling myservo.update() to have the myservo class take care off its own. Very OOP indeed :-)

For some reason I just can't get it to work. Brought down to the bare minimum, I have three source files, main.ino (off course), myservo.h and myservo.cpp:

myservo.h contains this:

Beware: Your 3D printer might be trying to kill you


Well, here is some scientific support (see attached pdf) to why your 3D printer might try to at very least harm you!

The study only incides over particle emission, and not the chemical nature of the emitted particles and yet it can be scary enough. That, added with my reported symptons after going on a 3D (ABS) printing binge: persistant chest pains/disconfort should be enough to keep you on your toes.


So you better ventilate/filtrate if you're into this messy business.

How many 9g servos can an USB handle.

I need some confirmation to be sure - USB 2.0 can supply 500mA, and typical small 9g servos draw like 150mA, right? That means it's safe to have an arduino powering 3x 9g servos, running off an USB port..?
Also, how important is it to have an electrolytic capacitor in the start of power supply chain, to store current? At least in this particular case - how much will it help protect the USB port? Or if all motors are stalled, capacitor will run out of stored power, and the USB port can still be damaged?

BEAM Robotics

I am building a three wheeled, light sensing BEAM robot as part of an engineering project, but my knowledge on electronics is very poor. I was wondering if someone could help me with the circuit. My robot is going to be light sensing with a touch sensor around its perimeter so that it can avoid obstacles.

Trouble Collecting


First day joining LMR. Love this site! I found a number of robots that I would like to follow the progress on. But when I click on the Collect link I get a HTTP error 200... I am using Google Chrome has anyone had this before?

Really sorry if this is this wrong spot for posting this, I did a search and came up empty...

ganging servos together

I am in the design phase of building a robot arm roughly 40 cm long that can pick up several pounds ( 1 kg for easy math).  To get a 40 kg-cm torque servo is a pretty expensive servo ($60 at pololu.com although anywhere else anyone knows something cheaper, please share!). 

Has anyone ever tried to gang several servos of the same brand and type together to work in concert?  I was going to put a balancing weight on the far end which will help, but still calls for a pretty expensive servo (30 kg-cm)

How to calculate how much weight my servo can handle?

I have a Tower Pro 9g Micro Servo (SG90) and it's datasheet says it's stall torque is (Stall Torque at 4.8 volts = 16.7 oz/in (1.2 kg/cm)), but as I haven't learned physics, I don't know how to calculate how much weight it can handle stacked on top of the arm/horn.