sourcing small through hole resistors - befaco

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Agawell
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sourcing small through hole resistors - befaco

Post by Agawell » Wed Jun 12, 2019 11:36 am

Hi

I bought a chopping kinky pcb/panel set recently and having sourced all the parts I didn't already have (or at least thinking I had) I began the build - only to discover, too late, that all the resistors (which I'd stood up) were too big and wouldn't fit - so after quickly trying to work out how to sandwich the 2 boards with the parts I have and realising that it's not happening, I start desoldering and searching for the correctly sized parts

tayda - none
mouser some in quantities that are ok - some in 4-5000 minimum order

I contacted befaco support, who directed me to tme - fantastic - they appear to have all of them, they are reasonably priced, BUT they have a minimum order of 100 - there are 18 different resistors

so I have to buy 1800 resistors (out of which I need under 100) at a cost of about 50€ + postage, for 1 diy module

even if I buy the ones available at mouser in small quantities - I still end up with nearly 1000 resistors over

ok I know I'll have stock and that I can use the small resistors instead of the bigger ones in other builds

TL;DR
does anyone know where I can buy small (3.7mm length) 1/4W metal film 1% tolerance resistors in quantities smaller than 100 (multiples of 10 would be great) and at a reasonable price???
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Post by Noodle Twister » Wed Jun 12, 2019 12:06 pm

Hi,
if they are the same as the small resistors used in the Befaco Spring reverb module, which I'm ordering soon they are here

https://www.taydaelectronics.com/resist ... s.html[url][/url]

Note they are 1/8w not 1/4w. 1/8w are smaller.

I took a look at the user manual for the chopping kinky as there is no actual BOM apart from the assembly instructions and the small resistors you see in the picture on the first page look to be 1/8w. Wonder where the BOM is ?

Most other Befaco docs are here
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Post by JohnLRice » Wed Jun 12, 2019 12:16 pm


Synthiq
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Post by Synthiq » Wed Jun 12, 2019 12:21 pm

Do they really need to be 1/4W? Mouser has more than 400 1/8W metal film resistors with length 3.5mm and can in many cases be bought for $0.021 each if you buy 10 of each value.

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NeolithicElectrophones
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Post by NeolithicElectrophones » Wed Jun 12, 2019 1:13 pm

I built a chopping kinky full kit and can say that the resistors matched the size of 1/8 watt ones bought from tayda recently. Or if you're feeling brave, Iv'e had no issue with using 0805 smd resistors on through hole designs like this.
Last edited by NeolithicElectrophones on Wed Jun 12, 2019 1:36 pm, edited 1 time in total.

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Post by Agawell » Wed Jun 12, 2019 1:23 pm

Thanks guys

That's great news - I've only ever used 1/4W or SMD unless they were in a kit and mostly from a BOM that either links or can be imported

and befaco support pointed me to .4W which is probably what they use as they can get thousands at a time - I'll try the 1/8W ones at mouser
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Post by Alfrede » Thu Jun 13, 2019 10:58 am

Hey and what is about MELF Resistors? are they an option?

They are like this:

https://www.reichelt.de/MELF-Widerstaen ... OUPID=8386

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Post by Agawell » Thu Jun 13, 2019 11:08 am

interesting - never seen those before - just looked them up on google and apparantly they mostly end up on the floor!

I think I can find most of the resistors I need at mouser in the .4W in 1/8W case small through hole metal film resistors (that befaco pointed to) with a few exceptions and I think I can get away with the larger ones for at least some of these
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Post by devinw1 » Thu Jun 13, 2019 11:18 am

Hey, I've noticed that when I buy TH resistors 1/4 watt form Mouser, the brand "KOA Speer" are always really tiny bodys. Yagaeo are large body like a typical 1/4 watt. Hope that helps.!

I actually normally choose the Yagaeos because I like the larger chunkier ones and want them all to look the same haha. But I could see how the little guys could fit in a way tighter space.

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Post by Whelm » Fri Jun 14, 2019 12:10 am

Is there a reason why Befaco uses such unconventional components for pots and resistors? I love their designs and their open hardware attitude, and the Rampage is maybe my most beloved module, but the inability to use any of my inventory of parts or even regular suppliers for their builds is a major barrier to my building more of their stuff.

I don't like buying kits but Befaco makes it such a hassle to source the right parts. :despair:

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Post by thetwlo » Fri Jun 14, 2019 12:28 am

They use 1/8 watt. found out the hard way a few years ago. That's not ideal. No idea why, they are a bit harder to find, and not so robust. I would avoid anything built with those 1/8W resistors, as they are only barely adequate.

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Post by jakobprogsch » Fri Jun 14, 2019 5:57 pm

thetwlo wrote:...and not so robust. I would avoid anything built with those 1/8W resistors, as they are only barely adequate.
Mechanically? You'd need to put about 5mA through a resistor with a voltage drop of the full 24V of a euro system to hit 1/8W? Most DIY euro circuits come nowhere near putting that much power through resistors?

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Post by muted » Tue Aug 06, 2019 11:59 am

thetwlo wrote:They use 1/8 watt. found out the hard way a few years ago. That's not ideal. No idea why, they are a bit harder to find, and not so robust. I would avoid anything built with those 1/8W resistors, as they are only barely adequate.
Three questions:
1) What do you mean by "they use 1/8 watt" - how do you know? I ask because the BOM says 0.4 watt.
2) What do you mean by "found out the hard way"? Did you burn a Befaco module resistor from overloading a 1/8 watt resistor in a build?
3) What do you mean by barely adequate? Adequate for what?

I have just bought 2 x Output v.III PCB/Panels,, and I dont want to fry them :)

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Post by J3RK » Tue Aug 06, 2019 2:14 pm

Panasonic makes 1/4W resistors that are about the size of 1/8W. They look like little bees kind of. :mrgreen: Digikey used to sell them. (that's possibly what John linked to above (I didn't check...))

I've used them quite a bit before in places that were a bit cramped. No issues. They may be a little expensive though. It's been several years since I bought them. Hopefully they still make them.
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Post by whoop_john » Tue Aug 06, 2019 2:38 pm

All the 1/4 watts I've had from Aliexpress have been the fine lead variety, with the usual size bodies.

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Post by kassu » Tue Aug 06, 2019 2:46 pm

I started buying these small resistors when I used to make all my modules on protoboard, because it gives a lot more flexibility in making the proto layout. I then started using them on some of my PCB designs as well, they make it possible to get quite a lot happening in through hole on a single PCB behind a eurorack panel.

Strangely manufacturers make same-sized resistors with several power ratings. Have a look at this Royal Ohm datasheet: the MF0W8 (1/8 W), MF0S4 (1/4 W) and MFF04 (0.4W) series all have nearly identical dimensions. TME sells the MFF04, Tayda sells the MF0W8 (on some values, but nameless brand equivalent on most values).

However, as others mentioned in most cases these can be used interchangeably. Any resistor of 4.7k or higher will dissipate less than 1/8W when placed directly accross 24V from the eurorack power supply. 1k and above can withstand 12V. For smaller value resistors it's good to check how they are used and how much current can flow through them.

One common scenario where 1/8W is on the edge is a 1k series resistor typically found in the output of many modules. In a misconnection event this could potentially see up to the full 24V across it, and dissipate more than 1/2 W, which could burn out the resistor if left like that for a long time.
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Post by J3RK » Tue Aug 06, 2019 4:08 pm

Quick update to my earlier post. Digikey still does sell those Panasonic ones. They are 1/4W, and are roughly 1/4" long. They're marked as Obsolete, but they still have quite a bit of stock on them.
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Post by FetidEye » Tue Aug 06, 2019 5:00 pm

most TME resistors are 0,01 ct, so if you order 100, it costs 1,- euro

So go for it!

At Mouser, you can also order smaller amounts than 100. sometimes the price sorting flunks out, press 'lowest first' (there is an arrow in the price column)

most resistors also cost 0,01ct for 10 or more

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Re: sourcing small through hole resistors - befaco

Post by roya » Mon Jun 01, 2020 6:59 am

So will the Tayda 1/8w resistors work on Befaco's modules? I already placed an order on Tayda, hope they do.

for example this: https://www.taydaelectronics.com/resist ... istor.html

Thanks!

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Re: sourcing small through hole resistors - befaco

Post by Eloc » Mon Jun 01, 2020 10:16 am

bitsbox.co.uk sell the resistors with the smaller package size in many values. They are 0.4W I believe too

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Re: sourcing small through hole resistors - befaco

Post by NeolithicElectrophones » Mon Jun 01, 2020 10:45 am

roya wrote:
Mon Jun 01, 2020 6:59 am
So will the Tayda 1/8w resistors work on Befaco's modules? I already placed an order on Tayda, hope they do.

for example this: https://www.taydaelectronics.com/resist ... istor.html

Thanks!
Yes, they are the correct size and work fine.

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Re: sourcing small through hole resistors - befaco

Post by roya » Mon Jun 01, 2020 1:29 pm

Great, Thanks

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