help identify part!

[KeithK]

This is in a Hobbico-accu cycle pro charger. the two resistors (one burnt one good) are the same value (there is another identical circuit on the other side of the board). My meter is not accurate at the low R value but I suspect this is a .1 ohm. any help as to what value (ohms, tolerance, Watts)it is and where I can get one ( I can also use a standard resistor with leads) would be greatly appreciated!

Keith

[Gary Warner]

I think the RL100 is a .1 ohm resistor, but don't quote me on that.

Does the good one read sub 1ohm?

BTW, what caused the resistor to burn. Fusing a .1 ohm resistor takes a lot of current, even at the SMD size.

Gary
--

[vintage1]

chances are its a balancing resistor in a transistor emitter/source and that transistor has also popped its clogs..

[Gary Warner]

"popped its clogs"

LOL - added to vocabulary

Gary
--

[KeithK]

Thank you for the replies. I am going to try a .1 ohm 1% 5W resistor I found at the local electronics store (one of the big gold type with fins). Ugly but should work. Don't know how it blew, but also charred some of the PC board behind it.

[westfw]

Something mark "100" would normally be a 10 ohm resistor, although I'm
not sure that follows for SMT parts (and it seems unlikely next to such heavy traces.)
(1R0 would be 1 ohm, and 0R1 would be 0.1 ohm.)

[imeins]

My 10ohm SMD are labelled as 100 in my parts box.

Ingmar

[Acetronics]

Hi, Guys

:rolleyes: A little serious help ...

http://www.farnell.com/datasheets/60935.pdf

just read ...

Alain

[imeins]

What a useful post Alain ;)

Thanks..

[KeithK]

I long for the days when you could pick up a resistor, see its size, read the color band and know what its resistance, tolerance and dissipation was. After more measurements I installed the .1 as posted above and the charger seems to be working good. I used an external volt and amp meter and everything measures within a few percent of the charger's meter. I don't want to risk removing one of the good resistors so I may never know if .1 is the correct value, but I can't argue with success. I even charged a Li-Poly with it!

Keith

[z-matrix]

be calm, that was a 0.1 Ohm resistor ;)

R means the .
100R = 100. Ohm, 10R = 10. Ohm, 4R7 is 4.7 Ohm ...

0.1 Ohm resistor, 1206 size, is rated at 0.25W. (should be 1.5811 Amps)
but it can take more because solder joints take the heat out, and you solder them on to copper (heat sinks).
P=I*I*R
I = sqrt(P/R)
unless otherwise stated in datasheet.
but for example you can use many in parallel, i have seen 50W+ load resistors made from arrays of little smd resistors, soldered onto copper bars.

[KeithK]

Z,

Do you know the manufaturer of the chip? sure would look better than what I used!

[MatC]

http://www.marsport.demon.co.uk/smd/res.htm
R100 = 0.1 ohm
Are you certain they are both the same value?
As regards power: if it says 0.25W, that will include the dissipation into the copper board at the ends, so I'd see it as a maximum rather than minimum.

[westfw]

R100 = 0.1 ohm
Yes, I want to apologize for introducing additional uncertainty. The leading R
certainly indicates a decimal point, and this is a 0.1 ohm resistor. Without
the leading R it would have been 10 ohms, and I might have expected 0R1,
but that would have dropped a digit of precision that I guess they wanted to keep.