[AMRadio] Charcoal Briquettes and High Voltage Power Supplies


bcarling at cfl.rr.com bcarling at cfl.rr.com
Sun Oct 30 13:52:10 EST 2005


In defense of the common carbon composition resistor...

On 30 Oct 2005 at 9:35, N2EY at aol.com wrote:

> Carbon comps aren't the most stable resistors in the world, and if they age unevenly you've got a problem. Worse, they usually have a max voltage rating of only 
> a few hundred volts, so in many designs they're being overstressed.

Er, not so - they are regularly used in commercial power supplies
in the 1000V to 2000V DC range.

Most amateur radio tube rigs used final HT of around 600 to 900V 
DC
and they used carbon resistors too, so I'm not sure where you got 
that idea from, but it is erroneous.

Many audio amplifiers and modulators use 400 to 800V or more.
Often a lot more.  As far as I know they all used carbon resistors.

If it still works after 10 years then I don't think it is fair to call 
this results of such a design "overstressed."

(Runs and ducks for cover...)





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