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Difference between 100ohm and 1K ohm resistors

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ohmygahitscoby

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Hey guys,

I needed a 100ohm 1W resistor, but Radioshack didn't have it so I bought a 1Kohm 1W resistor. Will this change the performance of what I need it for? I just needed one so I can drop something that puts out 20V down to 12V. Will it work? Thanks!


-Coby
 
I'm not sure about this but i think the more ohms there is the more resistance there is. so it might drop the voltage farther than you would want it to. but agian I'm not too sure but thats what i think.
 
It depends on what your connecting to the other side of it. fatkid is right, more ohms = more resistance = less voltage.

"watt" relates to the power capacity the resister can withstand being pulled through it. If you have a .5w resistor and your device is pulling 1w, it will fry the resistor.

I don't remember the math anymore... basic discrete electronics are so far back in my memory that it might as well not be there. ;)

I'll see what I can find that may help. There is a mathmatical way to figure this out.

On second thought, the easiest way would be to find a 5V zener diode. This will automatically drop the input voltage to 5V on the output side. However, your limited by similar current draw issues. If you pull more than it can handle, it will pop.

Radio shack should carry them at varying voltage outputs. They are usually pretty cheap.

Zener's also waste less power. Resistors absorb the voltage and dissapate it as heat, that's where the wattage comes in to play. Zener's are more of a "valve" and are tuned to allow certain levels of voltage through the "valve". So they are less passive than a resistor and cause less heat byproduct.

Here's something that may overeducate you, but give you the info on a zener:
http://www.reuk.co.uk/Zener-Diode-Voltage-Regulator.htm

After looking at that link a bit more closely, it actually has a nifty little calculator to determine the required resistor and zener diode to do what you want. You just need to know the desired output voltage, current draw and input voltage. Then it tells you the wattage requirements for the zener and the wattage/ohm rating of a resistor to do the same thing. It also gives you the schematic to build your voltage regulator.

Hope this helps.
 
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K would be 1000 ohms.

We had something at the shop we had to check that was in megaohms a week or two ago. On the phone with a tech trying to fix the welder. I can sorta get through the wiring and the relays and stuff. Had to call the tech back and make sure we had the meter set right.
Only thing I ever used it for was to check for power or continuity.

Looks like a real informative link Olds. Putting it in my favorites to look at later.
 
Oh okay. That clears up a lot.


I have another question.

I assume that the guy that did the mod (http://www.jeff-z.com/rcstuff/superbrain/superbrain.html) was able to use a 1W 100ohm resistor fine. If I were to use a 2W 100ohm resistor, would it still perform the same? As olds said, "watts" is the power capacity the resistor can withstand being pulled through it. If I were to go 1 watt up, would it still work fine? What if I were to use a 10W to be on the safe side?
 
1watt - 10watt, doesn't make much difference. That's just how much energy that can pass through it. 10 watt would be safer and would get less hot compared to the 1W or 2W.
 
Well remember I sold you my charger? I bought a Super Brain 959, which was a total drop. Installing a fan on the charger will somewhat help so I can charge more than one pack after another because usually it would get really hot after 1 charge. The output voltage of one of the wire where I connect the fan is 20V, so I needed something to drop down the voltage to near 12V for the fan. I'll see what my local Radioshack has :D.
 
Oh... so then why did you sell your charger? Seems like it does pretty much everything my superbrain 590 does...

I haven't had a need to charge sub-c packs on mine. It does fine doing repeated packs back to back at 1A or less (3 receiver packs and my remote). Otherwise I would have done that fan mod. I found that same link a long time ago when I got my superbrain (which I paid $20 from a forum member ;) ).
 
You know, I'm not really sure why I sold it. At first I thought I was gonna use it to buy some TC4 parts, then after I sold it I realized I needed a charger =/. I think I might sell it for another Piranha :hehe: . I payed $35 shipped for mine, so maybe I'll sell it for the same price and find one at the price I sold mine :D.
 

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