Resistors power

Started by POTL, February 25, 2017, 05:20:08 AM

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POTL


I had not paid attention to reschistorov power, but now wanted to go to the SMD and faced with the fact that 0805 is available to me 1/8 watt
Say for circuits operating from 9-18 volts 1/8 watt enough or worth taking 1/4 Watt (1206)

karis12

Might be safer to go with the 1/4 watt ones, although it's highly likely that you'll be fine with 1/8 watt ones.

POTL


as accurately as possible to understand?
I collect some effects madbean site as their schemes I calculate the resistor power?

EBK

#3
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  • SUPPORTER
Technical difficulties.  Please stand by.

POTL


it's interesting, but use 2 resistor in parallel pointless
conversely, I want to save space by using SMD

EBK

#5
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  • SUPPORTER
Technical difficulties.  Please stand by.

Phoenix

This discussion is pointless without defining its parameters.
The real answer to your question POTL, is that "it depends".

You need to CALCULATE the power required for each resistor - and that will depend on the circuit, it's operating parameters, and the resistors function within the circuit.

As a rule of thumb though, you should never use a resistor to dissipate more than half its rated power.

Generally, 1/8W resistors will be adequate in most pedal designs - but this is not something that you can rely upon. Make sure to use Ohm's law!

Also, keep in mind that higher power resistors will exhibit less thermal noise, so higher power ratings are better in noise senstive positions - but everything is a compromise, you have to draw the line somewhere.

EBK

#7
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Technical difficulties.  Please stand by.

duck_arse

breadboard your circuit with real parts, and then measure the circuits total current draw, work out the total power dissipation, and if it's still less than 1/8W, I'd say go with the 1/8W resistors.

or build the thing w/ 1/8's, power up, and if nothing smokes, box it.

also, throw in a pointless for me.
don't make me draw another line.