Let's Make Robots!


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wanted: fm stereo receiver

This is an electronics question that has little to do with robots. But this forum seems a good place to ask it anyway.

For an upcoming diy project, I am in need of some advice on integrated radio circuits. For my 93 yr old grandmother I hope to build a radio that can do this:

Poor Man's H-Bridge

So i've just started getting into electronics for the purposes of robots and the learning experience. 


Last night i manually built a H-Bridge using 4 transistors in a layout exactly like the one pictured here:



I then used the arduino to control the 4 transistors turning them on and off two at a time to redirect current through the motor different  directions.

I was just wondering what other things i should look out for in a real cicuit to do this, protection diodes ?


What on earth is this?

My wife "organized" one of my drawers, and this thing came up. What on earth is THAT I asked. "It is just one of your thingeys" she replied.

It had no batteries in it, so I inserted some.. and nothing happened.

I has:

A speaker, a print (with a black-blob-chip on it), and.. some strange "sensor" or something? Strange little thing with wires on each side, to hold it together? And to mystify even more, that can be "sealed off".

Also, on the side it has some mounting-part, that had some old no-longer-stickey tape on it.

Making a list and checking it twice...

I am ready to place the order(s) for my parts for my first bot, however do to the overall total, which is right around $130 USD I will be doing it in two parts, off of two different paychecks.

 I figured a good way to go would be to get the most expensive order out of the way, which is the one with the PICAXE starter kit, so I could start programming with some LEDs and such and such that I can pick up for cheap at Radio Shack.  However I have a few questions to make sure I have everything right.


So, here's my list that I am getting from Sparkfun

Terminology / acronyms / definitions

So reading around the site today, to get inspiration and to set a personal goal that I want to be at, I stumbled into more acronyms than the military throws around in a year.  So if anyone could direct me to a good repository of acronyms, or even a "Get Aquainted With the Terminology" site of some sort so I can understand the details, that would be awesome-o-tastic.

Something to help spread the love

So call me crazy, but even being as new as I am, I wanted to do something to help this place out, and since I can't make a revolutionary world changing bot, or even one at all right now, I did do these.


Now, I am by no means talented with graphics, but I like the simple clean look of these, and I feel that they can be used as banners or signature links in other forums to help promote this awesome place...just a thought.


Which to pick?

So I am getting ready to order everything for my first robot of doom (or so I hope it to become), and have run into a small snag.  I was going to go with the general consensus of the Picaxe 28X board to start with, however getting the Programming Editor to run on my Mac's OS X looks like nothing short of painful hours of pain.  I have heard that the Arduino board's Porgramming Editor works on OS X (I am running Leapord) and was wondering if maybe this should be the way to go. 

Comments and thoughts as to how to overcome my dilemma would be awesome.

A random coincidence

So I was updating my profile because I can't build bots yet (no parts currently) and I have only a ton of questions that I will slowly ask over time.  However, I randomly noticed that because I put my full name in, it put my display name of Chainer in the middle of my name with quotes, having it read Bryce "Chainer" Jenkins.  Now that wouldn't be very strange if not for the fact that I have been using the name Chainer for about 7 years now, and most all of my friends know me as Bryce "Chainer" Jenkins, and thats how I introduce myself on my podcast, display my name on

ARRG my track kit is missing

Well, I ordered the solarbotics track set earlier this month and it was supposed to arrive on the 16th but so far its a no show D:

I dont know what to do.. unfortunately I used the standard post option which is untrackable and uninsured so I am probably up the proverbial creek without a paddle. There was a typhoon that came across south east asia last week so I`m  hoping and praying it just got delayed a bit. Although with my luck its floating around somewhere in the middle of the pacific ocean -.-

Stupid question on ampere and motors

Probably a stupid question: if i have a motor driver that can handle at most say 1 A per motor, and two motors that consume say 2 A when stalled, what will happend when they stall? Will the robot simply underpower, or the motor controller burn, or what else ?

Help with Variables in Basic

This is a chunk of code I am using for my big tracks bot. I am using a irin command to accept inputs from a tv remote i.e. 2 is fwd, 4 is left, 6 is right etc. I am using #5 to goto my write command to enter the number of times I have hit each button onto my EEPROM chip. The Problem I am having is that the variable changes!! I have no idea why. Here is the code with some notes as to the problem. Any ideas?


EEPROM Addresses, Blocks, Nooks and Crannies

This is a general post to discuss the in's and out's of how much and where data is stored in an EEPROM.

My first question is with a 24LC16B. I am led to belive that, using the slave code and switching through the "blocks", I should have 8 blocks and 256 spaces per block to stick data. I am open to any ideas, explainations or tutorials.

Help with Remote Control Robot

I want to make a simple robot which runs by REMOTE CONTROL . It should be able to cross some hurdles such as stones etc. and also should be able to carry or drag ball to specified targets.so please help me to build such robot.

My entry for the Deadreconing

This is my entry for the deadreconing chalenge.

i posted it here because i didnt want to post it as a 

robot projeckt, because its made out of NXT (lego)


Scrapping Parts (sorry, deleted the other one(not on pourpose))

NEW: Anybody know what these are? I got them from an rc plane.


 this is the back:



This is a board of a different car. anybody got ideas?


Junkyard Challenge

Hi All,

I am new here. I have a following material

* Robot chassis
* 2 geared D.C. motors (6V D.C)
* 6 volt 4.5Ahr battery
* 4 ABS antiskid wheels
* 2 follower attachments
* 2 D.P.D.T. switches
* 1 castor wheel
* serial port programmer
* AVR Atmega8l development board
* L293d (2 x Channel H Bridge Motor Driver)
* 4 relay power driver



i2c new to me...

Allright Folks,

One of you all's gunna need to explain this whole i2c thing to me. I have done a wiki (which confused me even more) and a few google searches. What I have got so far is it is an extra little storage space that a pic can talk to. I guess there are "packets" of bits and addresses or something like that but really, I have no idea.

 Can someone explain this whole i2c thing and include some basic, pratical uses (and how to do it) when being used with a picaxe. --Explain it as if you would explain it to a 4-year-old.

Controlling belts

I set out to make an aggresive little tank and I got this far. It runs like a dream when I put a battery directly on the motors... in a straigt line. Any ideas on how to control it, so it can turn on a plate. All wireless.


Everything was made from old bits and pieces. I havent spend any money yet. 



Port problems on dsPIC33FJ128MC802

I have a problem that is driving me nuts. I am sure, that there is someting I just don't get, but can someone please tell me what?

 That setup is a dsPIC33FJ128MC802 which I try to program in C.

I have the following code (Let's assume that everything is setup and all ports are digital and outputs).

If I write this in my code:

PORTA = 3;

and take my measure thingy (danish for multimeter, I can see that Port a0 and a1 is high as expected. If I single step using the PIC simulator, I can see that PORTA is 0000011.

If I write this in my code:

Promising things on the horizon for LetsMakeRobots.com

Hey guys. I just wanted to give you an update on the upcoming changes we've got planned for the site. A month or two ago, after being frustrated at how limited our access to LMR's webserver was, I messaged Frits and offered to host the website on my own server. That way we would have the access to develop all the kinds of things we have in mind to continue improving the site and implementing all the great ideas we get.