Resistor wattage choice

[Pmelius]

I'm wondering how much it matters if I use 1w, 3w, or even 5w resistors in a pedal circuit over the typical 1/4w or 1/2w?  How would this affect the pedal and why/how do I choose the appropriate resistor power rating?

The reason I ask is because I have a HUGE lot of resistors sitting around, but most of them are >1w, and if I could use them in pedals with no issue it would save me a few bones (they also look super cool)

[GibsonGM]

You can use any type that you like (1W, 3W.....etc).   Most of the stuff we do, 9V, only requires 1/4W.  There's no upper limit other than physical size you want to handle!    I have *heard* that higher power-rated R's contribute less noise, but that may only apply when run at higher voltages...

To calculate the power rating you need, you need to use Ohm's Law.   At most basic, it is volts * amps  (milliamperes, in our case, so we make that a fraction of an amp.....15mA = .015A in this formula for example) = power in watts.     Watch those units 

Here, read this tutorial, it will help as there are many ways to arrive at power (Watts)...  https://www.allaboutcircuits.com/textbook/direct-current/chpt-2/calculating-electric-power/

In higher voltage circuits, say over 250V, you'd move up to 1/2W even if you only need 1/4W, due to the VOLTAGE limit of the 1/4 watters...suggested to use them at < 250V.     Cross that bridge later 


Welcome to the forum, Pmelius 

[Pmelius]

You can use any type that you like (1W, 3W.....etc).   Most of the stuff we do, 9V, only requires 1/4W.  There's no upper limit other than physical size you want to handle!    I have *heard* that higher power-rated R's contribute less noise, but that may only apply when run at higher voltages...

To calculate the power rating you need, you need to use Ohm's Law.   At most basic, it is volts * amps  (milliamperes, in our case, so we make that a fraction of an amp.....15mA = .015A in this formula for example) = power in watts.     Watch those units 

Here, read this tutorial, it will help as there are many ways to arrive at power (Watts)...  https://www.allaboutcircuits.com/textbook/direct-current/chpt-2/calculating-electric-power/

In higher voltage circuits, say over 250V, you'd move up to 1/2W even if you only need 1/4W, due to the VOLTAGE limit of the 1/4 watters...suggested to use them at < 250V.     Cross that bridge later 


Welcome to the forum, Pmelius 

Incredible information!  Thank you!

[GibsonGM]

It is, isn't it??  I didn't come up with it!!!   LOL   

Go learn Ohm's law, it will set you free!!!!!!!

[vigilante397]

Go learn Ohm's law, it will set you free!!!!!!!

Huge +1 to this. I don't use any of the calculus I learned in school, but I use Ohm's law every single day.

[Kipper4]

Welcome Pmelius


You get extra points for, point to point ,dead bug style ,mojo componants (tick) ,copper pipe ,anything steam punk ,70's pot knobs.
Someone here did a cool plexiglass box top with a super sweet deadbug circuit.
I wish I could find it.
Hold on was it EBK?
Hmmm

[Kipper4]

It was indeed.

http://www.diystompboxes.com/smfforum/index.php?topic=116898.140

[EBK]

It was indeed.

http://www.diystompboxes.com/smfforum/index.php?topic=116898.140

Still a work in progress.  There is a good chance I will finish that one in 2018 though.   

[antonis]

Eric, I've a lot of 20W resistors (some of them in a very attractive "gold" metal enclosure with small cooling fins..) and a bunch of 600 - 1000V capacitors (many of them of paper type..)
Would you like me to send them to you for your next project..?? 

P.S.
50A/600V diodes are also availiable for TS/Rat-alike projects.. 

[Rob Strand]

A fuzz face with 20W gold resistors and a 2N3055 would look awesome.

[EBK]

Eric, I've a lot of 20W resistors (some of them in a very attractive "gold" metal enclosure with small cooling fins..)

Could probably glue or bolt those together to make the outer walls of the pedal.   

I'll let someone else tackle that project.   

[thermionix]

A fuzz face with 20W gold resistors and a 2N3055 would look awesome.

I have two 1967 Silvertone "house number" 3155s, they look just like 2N3055s, but are actually Ge PNP power transistors.  I have not tested them yet, they're pulled from a dead amp, they might be shorted.

Still mounted to the heat sinks:

[Rob Strand]

have two 1967 Silvertone "house number" 3155s, they look just like 2N3055s, but are actually Ge PNP power transistors.  I have not tested them yet, they're pulled from a dead amp, they might be shorted.

All you need now is to get the 20W resistors  .
Leave the heatsinks on for added awesomeness.

[thermionix]

Maybe use 2 guage car audio cable with bolt-on connectors, giant motor run caps, make a FF the size of a suitcase.

Then power the thing with a single 50-cent carbon zinc battery.

But more seriously, would power transistors work out well in a fuzz?  Any special considerations?

[EBK]

Maybe use 2 guage car audio cable with bolt-on connectors, giant motor run caps, make a FF the size of a suitcase.

Then power the thing with a single 50-cent carbon zinc battery.

But more seriously, would power transistors work out well in a fuzz?  Any special considerations?

I'm convinced that the center of gravity for this special project is in Kentucky.  We'll ship you anything you may need (within reason  ) to make this happen.

At this point, we should probably double check if Pmelius feels that the original question has been fully answered.   

[Rob Strand]

Maybe use 2 guage car audio cable with bolt-on connectors, giant motor run caps, make a FF the size of a suitcase

After I saw the heatsinks I was actually thinking 19" rack and a fan.   
The pinnacle of Fuzz Face technology.

But more seriously, would power transistors work out well in a fuzz?  Any special considerations?

Should be OK.   In practice the gains are OK say 100 but you can get low ones and then the gain drops off a bit at low current.   It shouldn't be any worse than a germanium.   The capacitance might be a too high for Q1 but should make a smooth sounding Q2.

Apparently there's fake 2N3055's on ebay which have tiny little junctions and blow up in normal use.  But they would be good for a silicon fuzz-face,

https://forum.allaboutcircuits.com/threads/beware-of-recent-batches-of-fake-2n3055.118838/

[thermionix]

to make this happen

Nah, I checked and one of them is definitely shorted, the other doesn't inspire much confidence either.

It shouldn't be any worse than a germanium.

These are (were) germanium, PNP.

fake 2N3055's on ebay

Are those valuable enough to fake now?  'Cause I have some of those too that I'll probably never use.  Been sitting in a drawer for maybe 10 years.  I should check Ebay I reckon.

[Rob Strand]

re those valuable enough to fake now?  'Cause I have some of those too that I'll probably never use.  Been sitting in a drawer for maybe 10 years.  I should check Ebay I reckon.

That link was for Amazon (Sorry); I'm sure I saw someone complaining about Ebay.
I don't know if you can still get them.  Those dodgy companies keep popping up all the time
and they don't want to be found out.  There might be some leads in that thread.

These are (were) germanium, PNP.

Then they are really old.  I have some 2N301's and AD149's. These are Ge PNPs, probably from the 60's

[EBK]

to make this happen

Nah, I checked and one of them is definitely shorted, the other doesn't inspire much confidence either.

If a transistor is behaving like a short, I say solder that sombitch in as a jumper somewhere to teach it a lesson or at least serve as an example to other transistors who may be thinking about taking the "easy" route.   

[thermionix]

Then they are really old...probably from the 60's

1967, 40th week.