Understanding Resistors and Pots....

[Kunaak]

I am trying to learn how to do mods 100% on my own, and I have a few simple questions...

how are resistors rated?

like a 10 ohm and a 10K ohm, my guess is that the higher the number, the finer the tuning, but less the voltage can adjust?

like a 20K variable resistor is for a Vdimm mod, but a 20 ohm resistor would just fry it?

just guessing...

what does "15 turn" pot mean?

How do you test a Pot, for max resistance before putting it on a volt mod?

more questions come later.
I am just learning, I can do the basics, but I need alot of help. ;)

[Dissolved]

maybe you should just pay me to voltmod your stuff :D

[sandman]

I think the ohm rating is how much resistance it gives.

Like a 10K ohm resister will resist a thousand times as much as a 10ohm resistor.

That is why it would fry, because it lets too much voltage through the line.

Or, that's how I got it anyway.

[G H Z]

Originally posted by Kunaak
I am trying to learn how to do mods 100% on my own, and I have a few simple questions...

how are resistors rated?

like a 10 ohm and a 10K ohm, my guess is that the higher the number, the finer the tuning, but less the voltage can adjust?

like a 20K variable resistor is for a Vdimm mod, but a 20 ohm resistor would just fry it?

just guessing...

what does "15 turn" pot mean?

How do you test a Pot, for max resistance before putting it on a volt mod?

more questions come later.
I am just learning, I can do the basics, but I need alot of help. ;)

A vr is also known as a Potentiometer. You also see fixed resistors being used that are not capable of changing Ohms rating.

A 10 Ohm is exactly that, 10 ohms of resistance. The 10K is 10,000 Ohms of resistance. Big difference.

The "15 turn pot" is a potentiometer that has an adjustment screw that will make 15 revolutions from it's low to high setting. So a typical 10K vr that you can grab at RatShack(little blue guy), will start out at about 3.2k and 15 turns later will yeild about 9.4k.

To measure the resistance just place the two probes from your MultiMeter on the ground and one of the opposite legs of the pot. A good MM will self adjust to the correct reading without you having to select a range. Use the front leg and center leg of the blue guy. The highest Ohms measure will be with screw turned fully counterclockwise. Clip off the other leg in the rear.

Once you solder up the mod you will not be able to measure the pot's resistance, so you must do it before hand.



G H Z~

[asw7576]

higher ohm value => higher resistance => less voltage & amperage can pass through.

lower ohm value => lower resistance => more voltage and amperage can pass though.

Examples:

0 ohm means there is 0 resistance. The voltage and amperage can pass through the resistor 99.99999%

1K ohm means 1000 ohm resistance. The voltage and amperage can pass the resistor but with LESS values on the exit side.

Playing with resistor value enables you to manipulate voltage out, especially for any IC with voltage reference pin.

[Holst]

If you have a potentiomiter selection like me they are numbered as follows

1R = 1 ohm (not much resistance at all
1K = 1,000 ohms (quite a bit common for voltmods
1M = 1,000,000 ohms (or 1000K)

Obviosuly if you get an R mixed up with a K your gona have problems

[sandman]

Originally posted by MickeyMouse
0 ohms = ground
ground = dead HW
:)

that basically means that all the voltage will pass through, therefore frying the heardware. I correct in this thought?

[corbec]

Originally posted by asw7576
higher ohm value => higher resistance => less voltage & amperage can pass through.

lower ohm value => lower resistance => more voltage and amperage can pass though.

Examples:

0 ohm means there is 0 resistance. The voltage and amperage can pass through the resistor 99.99999%

1K ohm means 1000 ohm resistance. The voltage and amperage can pass the resistor but with LESS values on the exit side.

Playing with resistor value enables you to manipulate voltage out, especially for any IC with voltage reference pin.

isnt it the other way around? that higher resistance creates more elec? cause i popped 2 resistors off my 9800pro and i tried to start it for fun and it didnt get even warm

[sjohnson]

Resistors "resist" the flow of electricity. "In" voltage to a resistor is less than the "out" voltage.

In your case corbec, the resistors are part of a pretty complicated circuit. I wouldn't use that example to show resistance increases voltage, you simply cannot know what removing those resistors does to the circuitry of the 9800.

[Mrk200]

A pot is just a variable resistor (vr). When you see the rating for a pot, it is at it's max resistance. So generately and ideally, a 10k pot will allow you to adjust from 0 ohm to 10,000ohm.

As for how it relates to current and voltage, just use Ohm's law,
V=IR , where V = voltage (voltage across the resistor), I= current (through the resistor, measured in amps), and R is your resistance. So as you can see, an increased in R, results in a decrease in either V, or I, or both.

And when you see a wattage rating, that is power. P = IV, where power is measured in watts.

When you see people wiring a resistor in series with a wire (inline, lets call this R1), and then dropping a VR from the resistor to ground (lets call this R2), they are creating what is called a voltage divider. So, Vout = (Vin*R2)/(R1+R2). If you want a pic, let me know and I'll make something up on paint.

[corbec]

yes im confused a pic would help :D

[Mrk200]

Heres a pic of a simple voltage divider.

[Slickthellama]

you have to be carefull tho, some volt mods are done by increasing resistance. For example, i remember some old vmod, that you increase the resistance, and as the card measures the resistance and tunes the voltage accordingly, you would increase the resistance to fool the card into thinking it was getting too little voltage, thereby it would increase the VCORE. :stick: