### Author Topic: resistor problem  (Read 1770 times)

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#### karlis

• Full Member
• Posts: 79
##### resistor problem
« on: March 09, 2008, 12:50:19 PM »
hi, i`m new in this whole thing, well allmost, i`m not total noob in electronics

i`m trying to build line-folowing robot
what i got is
atmega16
rc car, which will be the base
4 IR diodes at moment, capacitator(100uF)(0.1uF), 5v voltage regulator, and 2 led's

i`m confused in part when i have to put everything to gather, i have seen bunch of tutorials, first was from here
and some other.. i dont understand whole scheme http://www.societyofrobots.com/images/sbs_avr_schematic.png
this sheme confused me so much i have stoped whole project...
my biggest question if WHY SO MUCH things are connected to pin7, whis is pin 7? that pink dot on left side, or thouse 2 on right side ?

in this scheme are shown 3 resistors, in photos are only 1, its because its power supply for led and IR's, but 2nd question is how powerfull resistor i need ?

all electronic stuff i can get in local shops, but cant get any help in my country because of selfish peoples who live here >.<

ps. i`m sorry for my bad language

#### paulstreats

• Supreme Robot
• Posts: 1,381
##### Re: resistor problem
« Reply #1 on: March 10, 2008, 06:15:22 AM »
The dot on pin 7 is for power (coming from the voltage regulator and not the atmega). It stands to reason that anything needing power will need to connected to it , that is why there are so many things with the same colored dot - it symbolises a connection to power and not necessarily pin7.

As with the resistor value its in the parts list of the \$50 robot. The tutorial where you found the wiring diagram has a parts list on the basics page

#### karlis

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• Posts: 79
##### Re: resistor problem
« Reply #2 on: March 10, 2008, 06:21:54 AM »
ok so that means i wire up battery pack with 100uF capacitator->voltage regulator->atmega, and starting from thouse 3 dots i can get 5v, correct me if i`m wrong

ps voltage regulator has 3 "legs" + - and GND, can i solder togather - and GND "legs"

#### paulstreats

• Supreme Robot
• Posts: 1,381
##### Re: resistor problem
« Reply #3 on: March 10, 2008, 06:26:27 AM »
Yes you can get +5v from that colored dot.

No, you cant solder together - and gnd.

The voltage regulator doesnt have + - and ground. It has input+ output+ and ground. Unless its a negative voltage regulator converter which would be useless to you.

If you put +7.2 volts(from battery) into the input pin and connect gnd or - from battery to the ground pin, the output pin will have +5v that you can connect things to (you also use the gnd pin on the regulator for gnd in the circuit too)

#### karlis

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• Posts: 79
##### Re: resistor problem
« Reply #4 on: March 10, 2008, 06:33:34 AM »
ohh sorry for so silly question about voltage regulator

amm now i`m litle confused about pin7, i connect there my output from voltage regulator, right... and on right side are 2 pink dots(No 20 and 21) can i connect there too ?

#### paulstreats

• Supreme Robot
• Posts: 1,381
##### Re: resistor problem
« Reply #5 on: March 10, 2008, 06:40:10 AM »
Connect pin 7 to your voltage regulator output.
Connect pin 20 / 21 to the voltage regulator output.
Connect any of the other same colored dots to the voltage regulator output.

You can connect pin 7 to the regulator and then connect pins20 + 21 to pin 7 if you like

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