Resistors Physical Size

[Herald1360]

+1 for endorsement of Akehabara. A bit like the heyday of Totty Court, Edgeware, Praed and Lisle but just better and much more!

Unfortunately I only had a couple of hours there, once, during a business trip.

[Craig Sawyers]

Originally Posted by Argus25

That doesn't surprise me. The only place I have been able to get these high voltage resistors (and a lot of other useful parts) is at the electronics markets in Akehabara in Tokyo.

Yes - I've been there, doubling up business with a bit of pleasure. The Sony Centre there is a thing to behold - Sony's showcase of stuff we might not see for a year or two in the UK, if ever.

Craig

[dseymo1]

Originally Posted by GrimJosef

I'm afraid it may be a difference in the way that power ratings are done. Back in the day a 1/2 watt resistor would survive indefinitely with 1/2 watt being dissipated in it as long as it was in more-or-less free air. Nowadays a 1/2 watt resistor is rated to survive 1/2 watt only if you can keep its surface at or below the specified temperature (often 70C). To do that you might have to immerse it in coolant or fasten it very closely to a large heatsink or at least cool it by keeping the leads short and soldering them to a large copper pad. If you just leave it in free air then the surface will quickly get hot and you may have to start using the power derating curve which is probably published in the datasheet somewhere.

Perhaps this sheds some light on apparently standard components sometimes being marked as safety-critical in service manuals.