Let's Make Robots!

Noisy LM386 based audio amplifier

Inspired by this post from Salvage, I ordered a couple of gameDR Smack Talk for the XBOX units. The volume is way too low to drive a speaker directly, so I need an audio amplifier.

That led me to this post from Calculon320 on building an amplifier with an LM386. I breadboarded the audio amp, and it definitely amplified. However it also added a lot of noise. It could be cleaning it all up on a perf board would fix some of that, but it is very noticable.

Practical question about servos and capacitors

I have read in many places on this site about using capacitors to reduce motor and servo noise. I am now using 0.1 uF capacitors across the leads of my motors as standard practice. I'm also using 470 uF and 0.1 uF capacitors around both sides of my voltage regulator. As yet I haven't tried applying a cap to a servo, and I have a quick question.


hello all, i am a bit confuse, although i am beginer i want some help.

i am going to start with a simple obstacle avoidance robot, the thing is :

  • i am going to put servo to hold ir sensor but now the quetion is do i have to put it through a resistor,or i have to simply hook up the servo to the output pin 1.



Is this something to bookmark? Anyone have experience with bildr yet? Does it apply to LMR as well?

[edit: LMR-II does support vimeo embedding!]

Stall Detection

Ok, here's my problem for you guys.  How do you use a MCU(Arduino, PIC, Stamp, etc) to detect if the bot has a motor stalled on it. I know it can be done, because I've read about bots that are bumperless and detect which motor(s) are stalled for collision detection.  Yes, I know you measure the amps that the motor is pulling, but how do you use the microcontroller to do it?


How to connect stuff?

I recently had the great idea of building a robot.


So I went and bought this:


and a PIC 18F4550 IC to go on it, as well as some wires and a couple geared motors and a servo. So... How do I connect all the stuff together so that it works?


I have never done anything with electronics before in my life.

PIC ports

I'm having problems with 18f252 ports. I seem to be unable to control it as an input or an out but. Thus I am also unable to use the BTFSC or BTFSS controls. Is there a difference between the 16f and 18f series with regards to inputs and outputs?


Sorry for the lack of info. I was in abit of a rush, I'm rushing now too :p

so the code i used is fairly simple :

The main part to control the 18f252 is ---->   MOVLW B'00000000'


Modifying source code (IR instead of ping)

So I have finally found a code that seems like it is going to work from this node:



However, I want to use a sharp IR sensor instead of the ping, as the sharp is cheaper and im on a strict budget for this project. I have no idea how to change the code, as I am just beginning to learn the language. Can anyone help me out? Here is the source code from that node:


Marry RC-Car and autonomous control

Has anyone been combining radio control car technology and autonomous controls?  I found the contribution by fritsl http://letsmakerobots.com/node/928.  It is over a year old now.  What has been happening since then?

Location, location, location!

Hello everyone!