Regular resistor VS sense resistor

Ohm's Law is mostly used to select current sensing resistors.

Pick the most stable one, like the current sense resistor.

"Kris Krieger"

** The fact there IS a circuit plus YOU know its purpose gives you the other info.

... Phil

Pick a resistor that can handle the power, this usually turns out to be a 'Current Sense Resistor' or "Current shunt" if its more than a watt or 2. They are more stable over temperature. But if thats not important in your circuit then a metal film at the proper rating would do.

Cheers

"Martin Riddle" wrote in news:5ORek.322$jS4.114@trnddc07:

OK, that helps, thanks!

- Kris

Sjouke Burry wrote in news:487be423$0$6026$ snipped-for-privacy@text.nova.planet.nl:

THat's helpfult, thanks!

- Kris

Normally one would infer type (such as say wirewound if it has to pass a high current ) from the context of the circuit.

All resisors are 'current sensing' so to speak.

Graham

Not at all - that's exactly how it's done.

Well, one ohm gives you one volt per amp, so it has to dissipate V * I watts - if you're sensing 5 amps, which is 5v across a 1 ohm resistor, that's 25 watts!

And, the precision of your measurement will depend on the precision of the resistor.

Good Luck! Rich

Eeyore wrote in news: snipped-for-privacy@hotmail.com:

I'm just learning (on my own) - don't yet know enough to infer much of anything ;)

- Kris

You need to know what sort of current will be passing thru the resistor. From there, you can determine the power rating of the resistor. It's overkill (size, cost) to use a 100W resistor if you only need a 0.1W rated unit.

-- Mark

Rich Grise wrote in news: snipped-for-privacy@example.net:

OH! OK, cool, thanks - I guess the only limiter there is the Ohm value in the circuit, and the Ohm vlaues available in current-sensing resistors (they don't seem to go over 10 Ohms).

Thanks ;) I'm teaching myself, so, although I've been reading a lot of resources, thre are still some basic questions that they leave out, so I appreciate teh info :)

- Kris

qrk wrote in news: snipped-for-privacy@4ax.com:

Yeah, some of these example circuits (my "learning tools") are not clear when ti coems to certian details - I assume that their typical readers know a whole lot more than I do ;) and re much more adept than I at figuring things out, but it'd be nice tohave some of the simpler things noted ;)

Thanks!

- Kris

I had the pleasure of servicing an electrically powered boat out in the boonies of Muskoka. I needed to measure the current draw from car batteries, so I cut a bunch of stove wire to short lengths and crimped them together with good terminals at each end to make a high watt .1 or .01 resistor, it worked well. The problem is to solve for a 100 amp draw without too much of a voltage drop, so a 0.01 ohm scoffs

1V, and 100W. Anyway, it's fairly easy to make a short length of Nichrome wire cable, economically. Ken

"Ken S. Tucker" wrote in news: snipped-for-privacy@e39g2000hsf.googlegroups.com:

REminds me of that old TV show, "McGiver" , where the guy would end up in various sitations and have to come up with all sorts of inventive devices, using only his wits and maybe a Swiss Army knife ;) Personally, I could do without the plot, and just go with the "if you're in this situation, here are some ways to get out" part ;)

MacGuyver.

You might try Survivorman or Man vs. Nature, on Discovery.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

"Tim Williams" wrote in news:XKdfk.59$m92.1 @newsfe02.lga:

Yeah, I watch those, esp. the latter (IIRC that's the one with Bear Grylls ).

Although I'd admittedly woeful with things electronic (which is why I have so many simplistic questions re: my over-complex attempted projuect ), I'm interested in things mechanical, esp. ancient engineering, since it's at the root fo modern engineering and presents a sort of "back to basics", or perhaps more accurately "back it inventive thinking" apporach.

Sometimes "how it's made" is interesting, although it tends to skip over a lot. "How To" shows and websites tend to be things I enjoy ;)

It' snto just the mechanics, tho', it's also fascinating to me because I'm interested in how the brain works, the process of how people come up with ideas. Or for that matter, animals, such as teh Green Herons in Florida who learned to use bait to amke it easier to catch fish.

Thre are too many fascinating things in the universe - I need a lot more time and a much bigger brain

- Kris