Batboard

I have a surface mount resistor that is labeled 851. Is it 850 ohms or 85 ohms? It is almost 1/4 inch long and almost 1/8 inch wide. How many watts is it?

851 "should be" 850 ohms. 850 ohms is non-standard, but could be a precision resistor.

6mm x 3 mm size. looking on DigiKey, I see a lot of 1-watt resistors in this physical size, but there are also 1/4 watt resistors as well.

arlojanis wrote:I have a surface mount resistor that is labeled 851. Is it 850 ohms or 85 ohms? It is almost 1/4 inch long and almost 1/8 inch wide. How many watts is it?

If your really in doubt, take an Ohm meter and measure it. I believe it to be an 850 Ohm value.

As to it's wattage, it's not a good idea to try and put much power through a surface mount resistor. They are not generally designed for that. Plus you don't have any cooling for them.

Jim

Usually, the marking are
NNM
where NN is numerical value, and M is the multiplier of that value, giving a value of NN*10^M

In this case, 85*10^1 = 850.

Were it 852 then the value would be 85*10^2 = 8500 ohms.