Tubes voice processor resistors wattage/voltage?

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neazoi

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In this voice processor

An improved volume-compression circuit

An improved volume-compression circuit
www.robkalmeijer.nl
I would like to know which resistors (anodes/cathodes/grids?) need to be of higher wattage than the standard 250mW through hole ones we use today.
If voltage is the problem, can I use two 250mW modern ones of half resistance value in series for each of them?
The whole circuit requires 5mA at 300Vdc from the power supply.
Thanks
 

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The whole circuit (excluding heaters) consumes 300V * 0.005A = 1.5W and the 75K resistor is already marked as 2W so the remainder can all be 0.25W quite safely. As for voltage, there are 0.25W resistors rated at 250V and more but if necessary make up the value from two in series. Their values do not have to be identical as long as the voltage across each isn't exceeded.

Brian.
 

    neazoi

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Thanks Brian.
Set aside the anode resistors (which must withstand higher voltage). How about the grid and the cathode ones? The circuit states all resistors are 0.5W unless noted. But for these grid and cathode resistors (5.6k at least) the current in them should be small so that regular 250mW ones could be ok to be used? The voltage at these places is not high, so as to consider this (resistor terminals spacing).
 

Don't confuse the voltage on them with the voltage across them. In most cases the anode will already be at high voltage so the difference from supply will not be all that great. For the grid/cathode resistors, yes the voltage will be much lower anyway. You should be able to run the whole circuit on a lower supply than 300V if it helps.

Brian.
 

    neazoi

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