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Newb needs help substituting part for Befaco Rampage
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Newb needs help substituting part for Befaco Rampage
StrangeCaptain
all, ordering parts for what will be my fourth or fifth buld.

Befaco Ram[age lists one resistor that Mouser doesn't have.

MFR-12FTF52-10M
Mouser says it's a Metal Film Resistors - Through Hole 10M OHM 1/6W 1%
Befaco BOM lists it as 10M RESISTOR,1% 1/8W


is this a critical difference?
If I can find a 10 ohm 1% that's 1/8W as the BOM lists can I use that instead?

The BOM calls out the manufacturer part number, not the Mouser part number so it;s possible it's a mismatch.

thanks!!!
ranix
Quote:
Mouser says it's a Metal Film Resistors - Through Hole 10M OHM 1/6W 1%
Befaco BOM lists it as 10M RESISTOR,1% 1/8W


is this a critical difference?


Nope, you've chosen a resistor that can handle more current (and more heat) than the one Befaco specifies.

If you'd chosen a resistor that was rated for less current than the one Befaco specifies that would be a problem.

It's 10MΩ which is the correct resistance, and it has a 1% tolerance, just the same as the specified component.

Quote:
If I can find a 10 ohm 1% that's 1/6W as the BOM lists can I use that instead?


What? You've contradicted yourself. I thought the BOM specified 1/8W.

If the BOM specifies 1/6W and you use 1/8W that would indeed be a problem. Unless you know the circuit well enough to know that it's not, which I don't.
StrangeCaptain
D'oh!

BOM is 1/8W

Mouser says that same part number is a 1/6W

Sorry about that.

can you run that by me again please?
StrangeCaptain
I think I got it.

if the spec is 10 Ohms at 1/8W with a 1% failure rate, then I can get anything that provides 10 ohms of resistance at 1/8W or higher wattage and should be OK other than paying for Resistance I don't technically need.

I found a 10M 1/2W 1% and other costing more it won't matter
Modulart_JP
This one will do:
https://www.mouser.jp/ProductDetail/594-VR25000001005FA1
If it's too big for the footprint, mount it vertically.
StrangeCaptain
Modulart_JP wrote:
This one will do:
https://www.mouser.jp/ProductDetail/594-VR25000001005FA1
If it's too big for the footprint, mount it vertically.


Perfect thanks! Added.

1/4 W is higher than 1/8 and not as high as 1/2!

thanks all!
search64
1% isn’t the failure rate, it’s the tolerance for the value. It means the actual resistance can be 10 ohms plus or minus 1%.
ranix
StrangeCaptain wrote:
I think I got it.

if the spec is 10 Ohms at 1/8W with a 1% failure rate, then I can get anything that provides 10 ohms of resistance at 1/8W or higher wattage and should be OK other than paying for Resistance I don't technically need.

I found a 10M 1/2W 1% and other costing more it won't matter


10 MEGohms

StrangeCaptain wrote:
I found a 10M 1/2W 1% and other costing more it won't matter


Correct, 1/2W > 1/8W. It costs a little more because it can handle a little more current and a little more heat.
khakifridge
Don't get too hung up on the power-handling specs. The reality is that you can't get resistors with power handling around what's "needed" in this case. Using a bit of Ohm's law, you can work out that the maximum current flowing through this resistor - if it were strapped between +12V and -12V (which it isn't) - would be only 2.4uA (millionths of an amp). The power dissipated (P=VA) would therefore be only 57uW (similarly). Any 10M resistor you can find will be fine. As noted previously, you may be more concerned with the physical space it takes up rather than its electrical characteristics.
joem
One thing no one seems to have mentioned so far (so maybe I'm getting Befaco mixed up with another company?): Befaco usually uses smaller size through-hole resistors than most through-hole modules. Befaco's are usually a little shorter, so you might want to consider the length as well. That said, you can still install a bigger one, just one side of it will be sticking up a little bit. Shouldn't be a problem, even if you did that with all your resistors on the module, but some people might not like the look of it.

Usually resistors spec'd for more than 1/4W are kind of big, so you might have a bit of trouble fitting a 1/2W resistor in the footprint on a Befaco PCB, even when standing it up. I'd stick to 1/4W or 1/6W or 1/8W to be safe, if you're not explicitly checking the size.
ranix
most surface mount resistors and capacitors will be in 0402 or 0603 packages. 0402 is the smaller footprint. I don't usually have trouble fitting an 0603 into an 0402 footprint. It's also kind of easy to get a through-hole resistor mounted on an 0603 footprint
StrangeCaptain
this is awesome info guys/gals thanks!!!!
joem
ranix wrote:
most surface mount resistors and capacitors will be in 0402 or 0603 packages. 0402 is the smaller footprint. I don't usually have trouble fitting an 0603 into an 0402 footprint. It's also kind of easy to get a through-hole resistor mounted on an 0603 footprint


Pretty sure all Befaco stuff is through-hole.
artieTwelve
joem wrote:


Pretty sure all Befaco stuff is through-hole.


Every kit I've gotten from them was through-hole.
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