New resistors

[RobN]

I ordered some resistors for damping from digi-key 1 watt 5% at different ohms. When I received them they are a lot smaller then the damping resistors I'm used to. They are only the size of my 1/2 watt resistors. At first I thought they made a mistake but after I checked they are correct. Has anybody tried using these smaller 1 watt resistors for damping? will they work? Here is the header from the datasheet-

Power Metal Film Leaded Resistors
FEATURES
• High power in small packages (1 W / 0207 size
to 3 W / 0617 size)
• Defined fusing characteristics
• Technology: metal film
• Meets active and passive flammability
requirements as defined in IEC 60115-1
• AEC-Q200 qualified (PR01 and PR02)
• Material categorization: for definitions of compliance
please see www.vishay.com/doc?99912
APPLICATIONS
• All general purpose power applications
• Automotive electronics
• Lighting ballast

[waltr]

Not sure of exactly which resistors you bought (Digi PN would help) but I do use similar power resistors and they do meet specs.
Actually I like these newer metal film R's much better for power than any of the older power R's.
They will work well for Damping.

[kt315]

L 11mm?

[Carl-NC]

I also bought a variety of 1W & 2W metal film resistors, I have trouble telling them apart from my 1/2W resistors. They work just fine.

[RobN]

These new ones I just received ain't even 11mm they are 7.35mm. About the size of my 1/2 watts. I will give them a try. Everything is getting smaller now a days.

[RobN]

Thanks all.

[kt315]

getting smaller now
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agree. i have wrote chinese resistors pins is only 0.4mm diameter, while old resistors pins is 0.5mm.
also chinese actively change cooper on ferrous metal in wires. i see cooper wires diameter in modern cable like men hair!
i am not able to solder those thin wires in USB and other sockets (((

[Skippy]

They are getting smaller, and have been doing so for countless decades. However the laws of physics still apply. If you're putting the same power into a smaller package, it's going to get hotter. So if heat is a concern, eg. other components nearby that don't like heat, etc, simply use two resistors in parallel ( or in series ) to obtain your desired damping R. Then they will run cooler.

[kt315]

skip

this is KOSCHEJ 5IM board. and you see much SMD ones on there.
those all resistors give 390Ohm -!

[kt315]

look on schematic skip

[waltr]

They are getting smaller, and have been doing so for countless decades. However the laws of physics still apply. If you're putting the same power into a smaller package, it's going to get hotter. So if heat is a concern, eg. other components nearby that don't like heat, etc, simply use two resistors in parallel ( or in series ) to obtain your desired damping R. Then they will run cooler.

True but what they are doing with newer materials is getting much better heat transfer (thermal coefficient) to the surrounding air.
This allows higher power (heat) dissipation in a smaller package.
Also, the newer materials do not burn with higher temperatures so can withstand higher power, just be careful not to touch them.

I do run parallel damping resistors for a few reasons.
1- Start with a 1k Ohm then parallel to adjust.
2- 1k Ohm on PCB and the parallel fine adjust R in the Coil cable connector. This allows each coil to be fine adjusted differently.
3- Distribution of power dissipation (heat). Just common engineering practice.

[kt315]

True but what they are doing with newer materials is getting much better heat transfer (thermal coefficient) to the surrounding air.
This allows higher power (heat) dissipation in a smaller package.
----
yup. but you have to know one fact. modern capitalistic system is too deceitful and vicious system in all history of humanity.
you just repeat you read around.
i did buy 10W wire resistors from chinese for repair. did put one in baking oven for ceramic (i have access on my job to it).
after heating and cooling the wire layer evaporated.