electronics, etc.

And it works very nicely. Here it is:

The line following robot

The robot in action

It uses a circuit like this (which i thought up and improvised myself):

The schematic of the line following robot

The circuit uses a LM324 op-amp. The setup trimmer is a 10k one, with a 100 ohm resistor in series. When supplied from a 3.6V battery, The series resistor for the leds can be, for example, 100 ohms. The resistors in parallel to the photodiodes are 330k. The final transistors can be anything capable of handling the current. This time, BD681 was used. The IR LEDs and the photodiodes were disassembled from an old mouse.

The leds, photodiodes and the operational amplifier (LM324) were just glued to the cardboard, the power transistors soldered to the servo motors and then everything was soldered to them. The robot uses a tiny 50mAh 1S LiPo.

I’ve been doing some other things instead of the CNC thing  for a few days now. The CNC router/mill/whatever (what’s the difference?) is having some kind of an identity crisis atm, because i don’t really know what i’m going to do with it.

I think i need to know it before i buy something new for the spindle. Surely it’s useless for a lot of things, but maybe I’ll find something to do with it. Probably milling PCB’s, if it proves out to be useful in that… which means i’ll just need to go and buy another mini drill for 20 euros.

Anyway, I built a ramp using scrap wood for my brother’s RC car:

size comparison

It was meant to be “big enough” height-wise, and it sure is. It’s a bit too narrow, which of course isn’t a big problem if you are a good driver!

rc car jumping

I have also been playing Command & Conquer Red Alert. Yes, the first one; the one which came out after the original C & C. Those two are probably the best video games I know of. Very original, runs on any computer, really good soundtrack. And very 8). 8) is the meaning of life.

Red Alert Screenshot (taken with a camera because print screen only gave out a mostly black screen. Yes, the screen is a bit broken but it doesn't disturb me too much)

Also, Windows 2000 is the best windows ever to be known. I installed it on the laptop i played Red Alert on and it just worked. (Well, you have to know where to get the drivers from and that you can enable the win95 compatibility mode with some strange command (which I always have to google))

HP still has their drivers for Omnibook XE3 available on their support site, which is wonderful.

I just broke my mini drill today which i used in the CNC mill. I guess I overloaded it when I cut some wood manually with it. It somehow burned and shorted some of the coils. Now the brushes make lots of long sparks and the drill has a fraction of the power it had before.

How to kill a mini drill

Some coils burned

co-tech mini drill

I have a cordless drill servo like this in the mill driving one axis:

cordless drill servo driving one axis

The control board looks like this:

cordless drill servo control electronics

It’s based on attiny2313. The software has a safety function which halts all operations completely until reset if it can’t turn the motor for some reason (which means bad contacts to motor or sensor or jammed motor). The attiny seems to work on very small voltage, and i have two signal lines running from the pc parallel port to it. If it halted, it was still powered on from the parallel port and the halt status didn’t go away.

I figured i’d just enable the brown out reset function of the AVR so it would reset when i cut the main power from it. It did reset, but the brown out seemed to go active almost always when it drove the motor, which means it probably made the voltage waggle too much. Here’s what I’m trying as the solution to that:

the fix

That is, a diode to the input side of 7805 and an extra capacitor to ground from that side of the diode. Let’s see if it works…

This is the most recent photo of my CNC mill under construction… nice colors, eh?

CNC mill 2009-10-05

I have already attached a mini drill vertically on the axis going up/down, but i took the picture before that (obviously). This is going to be the version 2.0. For new readers (that is, those who haven’t been on the irc channels from which i used to link to /random), here are the older versions:

1.0:

CNC mill 1.0

1.0.1:

CNC mill 1.0.1

1.1:

CNC mill 1.1