Let's Make Robots!


They will be packed as 5 sets with four different colors(red, dark blue, black and two silvery ones). Thanks for the effort from Oddbot, Robologist, Frits and … Read more

Picaxe LCD Direct Connection Problem

Hey There,

I've hit a snag on a project of mine. I've been trying to build a servo calibrator (to test a servo's limits and test them on robots before they're connected to the motherboard) which should operate by positioning a servo depending on the position of a potentiometer, and display the pulse rate on a 16x2 LCD. I've built one before, with an LED display and a single servo output, but this one should handle two servos.

Except it doesn't. I won't even handle one.  There's two major problems I've found which I'm looking for solutions to.

Powering Arduino and servos/motors with one supply

Helo, all

I tried to power Arduino (Duemilianove) and servos/motors it controlled with the same battery, but Arduino continuously restarted during the operation. Actually it was a surprise for me, since Arduino already has voltage regulator chip and filtering capacitors in the input circuits...

I solve this problem by supplying them with different batteries, but I don't like this solution. Could anyone help - how to provide single power supply?

Arduino servo twitching

Servo twitching. I know, simple stuff, but it's interesting to play with on new hardware. Another Arduino example "sketch" (they got a number of these) called Sweep simply moves a servo through a set range, back and forth. Just looking at the sketch (listed at bottom) this timeshows a servo controlsignla connected to pin 9. They recommend using the boards 5 volts to power the servo, which is coming from the USB connection. If I'd had a bigger servo, or was under load, it might be appraoching the 500 mA USB limit (or is it more now?).


Now this is one powerful servo from Trossen Robotics!

Watch your fingers!


Speaker Noise

Greetings fellows,

Still plugging away on my big project. All goes well, except my 8ohm speaker is giving off a trememdous amount of noise while it's on. It works fine, but there is always a high-pitched "white" noise.

In addition, my project uses small servos, and i've noticed a "click" sound come out of the speaker whenever I turn the servo off (low 1). I assume the problems are related.

Is there too much power going to the speaker? Do I need some sort of voltage regulation or supressive diodes or who knows what?

Cool little crab walker, simple 3 servo set-up, programmed in KicChip BASIC. Check out this video of one. Read more

Servo problem with "start here" bot

Hi all,

So a friend and I are working on our version of the start here bot. Everything is hooked up and working fine...with the exception of the servo. I am using the 28x1 picaxe with firmware a.5 (so this isn't a problem that i've seen in other threads about the wrong firmware). 

Confused about the 18X project board (servo connection, SRF05, analogue inputs)

I got a 18X starter pack because i wanted to learn the picaxe philosophy before actually building my first robot, but i'm almost starting to regret it as it's kind of hard to find informations, compared with the 28X1 which has plenty of documentation (here on LMR, or even in the manuals, which always refers to the 28X1 project board). Anyway i'm sure i still can do a lot with it, but i think i need some help...

What size are Servo screws?

I have some airtronic 94102z servo. What the screw size for the servo horn so I can connect it to stuff and also the screw size for the center of the servo?  I wasn't sure if all servo were pretty much the same except for the micro of course.  I did manage to find some for the center which are 4-40x1.  They seem to be ok so I'm sure if might work, but I want to find out from the experts out there.  Also where would be the best place to get screws for servo horns locally.  Thanks for your help.

Reuse Those Servos!

I'm kind of new here, so here is my first post. It might seem dumb at first, but I think it's a great idea. I've read a lot of posts about people frying their servos (hint: fritsl's cheap tiny blue ones, said so himself! :), so I came up with a money saving solution. REUSE THE SERVOS! YA! 

Servos are expensive after all, and they do have some good gears and they mount easily. So if you fry one, I wouldn't panic too much. 

See, why would you want to spend money on this-

Update 26/04/2009 I have added a video to show the picaxe modifying the servo signal based on the output from a Maxbotix EZ0 (EZ1 version here at LMR). The … Read more

Robot guitar amplifier

OK, here's what I'd like to achieve: I want to "robotize" my guitar amp so that I can record and recall each potentiometer's positions (i.e. volume, tone, reverb, etc.).

Why is that? Because I don't want digital voltage controllers to interfere with the signal path within the tube amp, hence the need for a mechanical actuators for each potentiometer.

I already have some designs in mind, but I would like to know what kind of parts I should get (i.e. what kind of servo, what kind of optical shaft encoder).

I'm looking forward to read your advices


Correct servo voltage, aka Rudolph's head starting to hurt...

Okay, I just don't understand. Servos are supposed to run at 6 volts, right? That's what the back of the package (of the ones I have a package for) says.

When I supply 6V (currently 4 AA batteries) the servos all max out at one end of travel and stall (tested all at once _and_ individually).

If I change the servo voltage to 5V (one at a time, since the 7805 prolly doesn't want to run seven servos) they work just freakin fine.

This is the result of a couple of tests with recently arrived microservos + programming + polymorph shaping technics + recently build G'Remote :-) Read more
I know, not a very original name. It was that or "Simple junkbot for a boring, rainy Sunday afternoon", but I figured that was too long to type repeatedly. This is … Read more

Super Brilliant Avoid Obstacle Strategies - Open Question

I have built a Bot with Arduino as MCU and wish to give it a life of its own.

Has anyone Created a "Super Brilliant" Strategy for avoiding obstacles ?.

So far my bot does this (rather On/Off control) :-

(1) When it detects an object Right it turns Left until the coast is clear and carries on with its original direction.

(2) When it detects an object Left it turns Right until coast is clear and carries on with its original direction.

The meanest of servo jitter!

Working on a project, where I want a servo to rotate/position a laser that is reflected to a mirror, that is vibrated by magnetic pulses.. every day stuff here on LMR :)

Earlier I posted this:


- And now it was time to hook it up.

However strange things happened. When I was pulsing the mirror, the servo was moving!

Since I started messing with robotics that I wanted to build a tank, and finally that moment arrived when two Tamiya thread kits and a Twin Motor Gearbox arrived. … Read more
 These kits have been discontinued and are no longer available   This is the FET version of the giant servo kit from Oatley Electronics. Will easily handle … Read more
The GWS servos are extremely easy to modify to continous rotation, here is how :)
Thanks to  ndupont for this: http://letsmakerobots.com/node/4873 and to Anders for this:http://letsmakerobots.com/node/259 - Now I had some GWS-servos that I … Read more

servo servo PICAXE

Alright all, very simple question:

I have a picaxe 28x1 board

It will have 7 servos

Those servo's will have to move arms and body parts

I am looking at these:


question 1:

Is continous okay?

question 2:

are they good?


A snake robot. Serpentine locomotion and other snake gaits read from a micro SD card. Obstable avoidance and eventially path planning.
Using a
This is our entry into the PIC32 challenge. Please check it out on http://www.pivut.com/snake.htm and VOTE FOR US before 2/10/09! It is our first robot. All of the … Read more

Servo mounting for "up-down" movement

hello, i was just wondering: which is the best way to attach a servo to a chassis so that it can move an attached camera up and down (no left-right) ?

Good servos at the right price?

Now that I'm building so many robots servos have become a big issue with my budget. I've spent a lot of time looking for better servos at reasonable prices. The credit crissis hasn't helped. Being in Australia can be a disadvantage too with the poor exchange rate, shipping cost etc. Basically I want to know what do you think are the best value for money servos around today and where to get them in three basic categories:

Cool Arduino Library for driving servos!

I don't know if you guys already knew about these 2 very useful library to drive servo motors from the arduino, basicly you don't need to use analog write with an hexadecimal value to drvie the servo by PWM, you just write in degrees the angle and direction you wish the servo to go and it goes! 

Anyway here it is :


Servo problem: only 1 direction.

Another noobquestion here :)

 We have a servo modified for continuous rotation and when we get the 5V power from the PICAXE 28X1 it works just fine, but when we attach the red and black wire directly to a 9V battery it turns only one direction (Clockwise). It seems it's not making a difference between clockwise and counterclockwise :(

 This is the code:

servo 0,75
servo 7,75             =for the servo bug :(
pause 1000
low 0
pause 1000
servo 0,225
pause 1000
low 0
pause 1000
goto main

Parallax Servo troubles

Ok i am having troubles working with this servo on my robot.  It is the same as the start here robot.  i type in the code

Servo 0,150

ans it barely moves then i type in

Servo 0,225

and it barely moves then i type in the whole code and it keeps turning and turning and it won't stop.

 The servo is a parallax continous rotation one.  I played around with the screw on the bottom and it has slowed it down and turned directions but nothing really.

any help will be nice


How, When, Damn it, Why do servos jitter?

I've had a lot of trouble with servo jitter lately, I seem so have solved the problem but I'm not sure why it has worked.

servos.jpgAt first I thought it was the power supply being spiked, no amount of decoupling capacitors solved the problem.

I thought it was software and although my code was improved, the jitter continued.

Because I was using optic sensors, I thought fluctuations in the light is causing my inputs to give false readings. Still no luck and I stubbed my toe in the dark.