Replacing 1/2w carbon resistor with 1/4w

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DjPsychic
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Post by DjPsychic »

Hello,

I'm in the process of modding a vintage Thomas Organ Crybaby. I was going to use some 1/4W carbon comp resistors that I already have to replace some of the stock 1/2W for mods.

Is this ok or should I be using matching 1/2W?

Thank you :)

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plush
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Post by plush »

Yes, in this case you can.

But please, next time, learn ohm's law.

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The G
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Post by The G »

plush wrote: 24 Oct 2020, 07:57[,,,] But please, next time, learn ohm's law. [...]
I just took a second look at the Ohm's Law and... I don't get it ¯\_(ツ)_/¯. As I see it, resistor parameters that are usually relevant are its electrical resistance, maximum power dissipation and noise. I presume the OP will replace with resistors of the same electrical resistance, but half the maximum power dissipation. What am I missing?


To the OP: if you're modding the pedal and not aiming for the vintage correctness, why wouldn't you use metal film resistors (lower noise)?

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plush
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Post by plush »

The G wrote: 25 Oct 2020, 12:28 I just took a second look at the Ohm's Law and... I don't get it ¯\_(ツ)_/¯
You choose your resistor power rating based on it's maximum power dissipation in its current application, which can be calculated using ohm's law.

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The G
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Post by The G »

Thank you. So, the full process would've been
  1. OP provides the schematic.
  2. Having resistor values and supply voltages, one could calculate the dissipated power for each resistor using the power formula P = I × V = R × I2 = V2 ⁄ R.
    Or we could calculate that a resistor needs to have a resistance less than 324Ω to dissipate more than 250mW (1/4W). Thus, assuming that all Thomas Organ Cry Baby resistors have higher resistance than that, one can replace all resistors with their 1/4W variants, without calculating the voltage across each resistor.
Am I close :D ?

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plush
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Post by plush »

The G wrote: 25 Oct 2020, 16:16 Am I close :D ?
Lol, u mad :D
But, yeah, pretty close :lol:

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DjPsychic
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Post by DjPsychic »

Sorry, I realize that might have been a dumb question...

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Post by andy-h-h »

DjPsychic wrote: 07 Nov 2020, 01:00 Sorry, I realize that might have been a dumb question...
There are no dumb questions - the responses on forums on the other hand...

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