50$ robot voltage regulator question...

[dwb4629]

howdy!

so... i'm new at this, i'm sure you haven't heard that one before, but i just finished the circuit board for the 50$ bot, my first circuit board ever, and i tested it and it's getting power everywhere it should.  i've built the one that uses the battery holder and the 9v.

heres my situation, while testing it with the 9v it had 9v into the voltage regulator but was putting out around 8.3v.  it was a steady voltage, the only time i've seen my digital multimeter hold a steady number for more than 5 seconds, but thats to high isn't it? that reading was without a load of any sort.  will putting a load on it bring the voltage down to where it should be? is this normal?

heres another variable... i work right next to radio shack and when i can get components there i can, and the voltage regulator was one the components i found there.  i've come to find out the the radio shack vr is a "fixed" voltage regulator while the one on the parts list is a "linear".  i can only imagine there is a difference but i cant find much explaining the difference.
 
i thought i could have damaged it with my exceptionally terrible soldering skills, so i bought another one today, and an led (a cheap load), and because i apparently can't pay attention to fine print i got one rated for 3 volts. so i got home and soldered it into a practice board, and tested it all again, the voltage regulator was outputting the same (8.3v), but for the 3 or 4 seconds of led i had before it fried, it did drop to about 7.5v. am i on to something?  any help would be as awesome a getting a free bioloid. 
 

[paulstreats]

You are definately doing something wrong. The fixed voltage regulator is also a linear regulator. The fixed means that it outputs a fixed voltage (variable ones can change their output voltage). linear is just the way that it reduces the voltage from the input to output (another type is a switching regulator)

Okay, so this might sound silly. But is it the same make and model of voltage reguator you have that is in the tutorial?

 The reason that i ask is that different makes of voltage regulator assign the input and output pins differently, I know that there are only 3 pins but still different makes utilise these pins differently. So the one in the tutorial has the left pins as input voltage, the center pin as gnd and the right pin as output voltage.

 I have some that look exactly the same as in the tutorial but the left pin is input voltage, the center pin is output voltage and the right pin is gnd.

 You really need to check this out. So go to datasheetcatalog.com and type in the letters/numbers that are printed on the front of your voltage regulator into the search box. You should find the datasheet for that specific component and it will tell you what pins are what....

(p.s. It took me ages to work out why my new voltage regulator didnt work properly....)

[dwb4629]

word.  thanks dude.  i looked around, and it turns out the i/o pins are reversed on the radio shack voltage regulator.  and fyi for anyone really, the datasheetcatalog website does not support radio shack parts and the radio shack site doesn't seem to list pin out information under there tech spec section.  i mean it seems like pin out info is pretty important tech specs but i guess they think otherwise.  but the box was still in the trash.  something i should have looked at a week ago when i started this.  so if i'm going to take anything away from this, details should not really be overlooked in regards to circuit board fabracation, and you should always look at the pin outs on the back of the package before you throw it away. also keep your trash can full until you finish a project. thanks again.