Error in $50 Robot Tutorial? Capacitor 10uF or 10mF ???

[GUmeR]

Here:
http://www.societyofrobots.com/step_by_step_robot_step3A.shtml
At capacitor description, to reduce electric noise:

The value of this capacitor doesn't really matter, but 10mF and above is a good starting point.

Shouldn't there be 10uF ?

[ed1380]

yes. and admin used a 220uf one

[TrickyNekro]

Depending on the noise freq you want to cut...
A 0.1μF cap (10uF) is well suited... (micro is the Greek m but our μ is close to u... It's not the right symbol in the SI but used for practical reasons)
Solder it as close to the power supply of the chip as possible for better results...
Also if you have an osclinatorscope you can test and suit the capacitor the best!!!

Cheers from Greece
Lefteris!!!

[gamefreak]

would a 104 capacitor work? I cant seem to be able to figure out the code on them....

[Maltaeron]

Yes, 104 is good, thats what I used 104 is 10 with 4 zeros, or 100,000pf, or .1μF

[GUmeR]

Actually I know that. I just don't want any new bite going from shop to shop looking for 10mF capacitor . And then wonder why his 10mF is bigger than whole robot .

[Admin]

Oops thats a typo . . . I'm correcting it now.

I used 220uF, but you'd really want a lot more. If you have many servos, you'd probably want 1000uF or more.

As for capacitor size, it also depends on the voltage rating. You wouldn't need it rated for more than 10V, so if you found a cap rated for 50V, then it's 5x larger than you need it to be.

[spizzak]

I have  a few questions on this matter.

1. I'm planning on running 3 servos, maybe 10 LEDs, a 20x4 LCD, an IR rangefinder, and a few other small things. Can anyone suggest how much capacitance i'll need?

2. I have 100uF, 220uF, and 330uF capacitors all rated at between 16 and 40V, can I still mix those and connect them as shown in the diagram or should I only connect ones of the same rating?

3. Which I/O pins need to be connected to the capacitor and unregulated voltage, and which I/O pins need to be connected to the regulated 5V.

4. Is it just the servos that need to be connected to the capacitor or all digital pins, or does it matter?

[SmAsH]

you really should have started a new topic for this...
but anyway... yes, capacitors can easily me mixed and matched in parallel to add capacitance.

1. the only things i would worry about drawing current is the servos, all the rest draw near zilch. 220+330 will most likely be good enough, these are just ordinary servos right? nothing giant and power hungry?

2. nope, go for it.

3. NO I/O pins should ever see unregulated voltage over 5v. this will damage and most likely fry your microcontroller.
microcontrollers and most sensors will die if they see over 5v.

4. wherever you have an unregulated power bus there should be a capacitor if there will be servos on it.
for some people, they require some digital pins to have 5V buses, this is sometimes fine too.