Why do some circuit boards have square resistors?

 

Because whoever designed the circuit and/or the board chose to use them....?

 

Those look like they have low resistance values (2.2Ω and 0.82Ω) and it may be easier to make them in a small square package since they would have a short resistance element.

 

they run out of donut, sphere and pyramid shaped resistors?

 

Hi,
Resistance value is more important .shapes dont mind it.As long manufactures designed the accuracy is next valued.

 

Hi,
Resistance value is more important .shapes dont mind it.As long manufactures designed the accuracy is next valued.

Yes and no. For many circuits, parasitics are very important and thus not only can how the component is manufactured be extremely important, but also how the component is laid out on the board both relative to the board and its traces and relative to the other components.

 

I think those are actually inductors.

 

I think those are actually inductors.

The form factor might suggest it, but do they mark inductors with an 'R' for the decimal point?

And what would the values be? 2.2 H??? I suppose a convention might be that it has in implied scaling prefix, like many picofarad capacitors do.

I haven't run into too many components marked with this convention (and no inductors, that I recall) but on schematics I've usually seen R used as the radix for resistors, F for capacitors, and H for inductors.

But certainly a noteworthy observation.

 

The implied scaling is uH so it would be 2.2uH, see this for instance http://uk.farnell.com/kemet/mplc0730l3r3/inductor-power-3-3uh-20-smd/dp/2364592 It is quite typical for high current inductors in power supplies on motherboards and similar stuff.

 

Very odd that they use R as a decimal point for an inductor.
Seems like it was done by some manufacturer who doesn't understand marking convention.

 

Very odd that they use R as a decimal point for an inductor.
Seems like it was done by some manufacturer who doesn't understand marking convention.

Possibly. But if so, it would only serve to further emphasize the oft repeated admonitions about assuming that component markings follow some rigid convention.

 

Hello,

Even a large player uses the R in the coding:
http://www.bourns.com/news/press-re...dc-dc-converter-power-management-applications


Bertus

 

The first time I came across the R notation, I thought it means "radix", but I was told it meant "resistor" and they pointed out some F and H (on schematics). I've even seen schematics that use Ω on resistors (you'd be insane to use O for ohms). Now I'm wondering if perhaps I wasn't that far off in thinking of the R as the radix when no scaling prefix is appropriate.