50 Dollar Robot Questions

[brian]

Hi so I finished the board for the 50 dollar robot and got it programmed and everything.
But the LED wont light up (its not burned out either)... However if I place an LED on the port closest to the resistor (PD 4 I believe) that lights up.

EDIT: It appears that if I make it so the shorter lead (negative) is closer to the DIP socket it works... my circuitry looks right though... but the schematic says otherwise.

Any help would be appreciated.


EDIT Again: It seems the LEDs I got are backwords  I tested it and the shorter end is positive... Well, that seems to be my problem.

[theleb]

In the $50 Robot tutorial, the parts list has two different types of resistors...which do we use for which part?

[Admin]

It seems the LEDs I got are backwords   I tested it and the shorter end is positive... Well, that seems to be my problem.

Hmmmm thats really odd . . . the longer end is positive and should connect to power. Also, if you look at the LED, you will notice that it isnt perfectly round - there is a small flat ridge around the perimeter. That flat ridge is the negative end. Does it work now for you?

In the $50 Robot tutorial, the parts list has two different types of resistors...which do we use for which part?

The 340ohm resistor is for the LED, but if you want, you can just use the 1.62Kohm resistor for everything. It doesnt really matter that much for the LED.

[theleb]

I'm a newb. I completed the circuit board for the $50 Robot, but I don't have a multimeter or other testing supplies.  When I attached a 5V power supply to the ground and the battery + pins, I got small sparks, but nothing happened.  The LED did not light.  I later (foolishly) tried attaching my 5V power supply directly to the soldered-in LED to see if it was breaking my circuit, and it lit for a split second then went out forever.  I suppose I'll just start over, but are there any suggestions as to where I may have messed up the first time based on my vague description of the test?

[HDL_CinC_Dragon]

Well the thing about that is the problem could be literally anywhere in the circuit

for starters, which setup did you use in regards to power? Did you use the 6v NiMH battery pack or go with the 9 volt + AA battery pack layout? When you say you hooked up a battery to the "ground and battery + pins", what do you mean? Directly on the ATMega? or did you mean on the 3 pin battery header?

Also, make sure you dont have any short circuits under your ATMega. Its a pretty close squeeze under there! extremely easy to make an accidental connection somewhere that its not supposed to be.

[theleb]

My circuitry is pretty sloppy since this was the first time I had ever used a soldering gun.  I'll just start over.  By the way, though, I was using a 6V power supply of 4 AAs at 1.5V each.  I also thought it was kind of interesting that my ATMega didn't fit in the DIP socket cleanly.  Maybe it was damaged during shipping.

[Rebelgium]

I also thought it was kind of interesting that my ATMega didn't fit in the DIP socket cleanly.  Maybe it was damaged during shipping.

DIP ICs are always a tad too wide for DIP sockets.

Just take the IC, put one row of pins on the tabletop, and press it gently down. Now the other row of pins to.
So the pins are bent a little bit inwards. That should do the trick

[Admin]

When I attached a 5V power supply to the ground and the battery + pins, I got small sparks, but nothing happened.  . . . are there any suggestions as to where I may have messed up the first time based on my vague description of the test?

You shorted ground and power, most definitely. Check your wiring.

Chances are your other circuitry was bypassed in this short, so probably nothing but maybe the battery (and regulator?) was damaged.

I believe RadioShack sells basic multimeters for like $20 . . .