Knowing How to Source Components

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Vortico
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Post by Vortico » Tue Jul 25, 2017 1:42 am

This is the case with metal film. 5% is the best you can get with carbon film.

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duff
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Post by duff » Tue Jul 25, 2017 2:10 am

Vortico wrote:This is the case with metal film. 5% is the best you can get with carbon film.
Ah, ok I was jumping to the conclusion that the 5% resistor was carbon.

I have never seen >1% tolerance metal film resistors at a price where a hobbiest would buy them - i.e at a price per quantity where 1% Metal or 5% Carbon are not cheaper. Maybe I am looking in the wrong places, but I assume if purchase direct on an industrial scale they are more economical. Hence my mind is somewhat locked to the idea that 1% = Metal Film & Carbon = 5%.

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Post by Vortico » Tue Jul 25, 2017 4:28 am

I now see that Willzyx was talking about carbon film resistors, so my mistake.

Although, I've never had a reason to use carbon over metal film resistors, even if I don't care about the resistance value. Carbon film has higher inductance and capacitance so you might get noticeable slew/filtering in the supersonic range, are usually noisier, have a higher TCR, and technically don't last as long (although still much longer than caps and ICs, we're probably talking 200yr vs 100yr).

If you need <100Ohm, none of the above applies, so use carbon all you want.

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Post by Multi Grooves » Tue Jul 25, 2017 6:32 am

rithma wrote:@Multi Grooves -
yep, same Rithma, released a number of things on Om way back when.
It's been a few years since i released music but I think Om is still going strong.

/rithers
:hail:

Wow, nice to e meet you. I met Mark Farina for the first time last year in [sun ce beat] Croatia. I still play the OM lounge and King Kooba stuff to death. I reckon you guys had the best art work/design of your day. How come you stopped making?
...but Cynthia, my Daddy never had a heath kit..

FS: SSF Entity

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rithma
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Post by rithma » Tue Jul 25, 2017 6:28 pm

Well *this* has gone off topic so i'll keep it short:
Stopped releasing music possibly as a result of:

1)Hard Drugs
2)Rehab
3)Kids
4)Busy Soldering

kind of in that order. Finally getting back into some sounds recently, and it is FUN!!!

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Re:

Post by Kawouddd » Fri Apr 02, 2021 6:47 am

decaying.sine wrote:
Tue Jan 18, 2011 11:24 pm
Resistors are the easy part. Just get all metal film 1%. They are cheap if you buy in bulk. I only get 5% (the tan ones, generally) for more obscure values that don't have 1% readily available.
N00b question.

So, with wattage and resistance matched, is it fine to sub in some Tayda 1% metal film resistors in a project where almost all other resistors are 5% carbon film? [having browsed the last two pages, fairly sure this is yes.]

Second question.

I can find these MLCCs with matched values on Tayda EXCEPT voltage - the Tayda ones are 100v vs the 50 on these. Is this a problem?

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Re: Knowing How to Source Components

Post by cygmu » Fri Apr 02, 2021 9:46 am

Those specs will be fine.

Metal film resistors are in most respects superior to carbon film and 1% tolerance means they are meant to be closer to the nominal value than 5% tolerance, so the circuit will operate more closely to the "ideal", whatever that means. As for power ratings for resistors, you don't have to pay much attention to the difference between 1.8W, 1/4W etc for most values: anything above 4.7k cannot possibly be required to dissipate more than 1/8W in a circuit powered by +/-12V (power = V^2/R, V is 24V max) and it is pretty unusual to have 24V right across a resistor.

Likewise for capacitors, anything with a voltage rating 50V and up is pretty robust to the voltages you'll see in your synth.

Sometimes as power rating or voltage rating increases the package size of the part also increases so it might be worth making sure the parts you are buying will fit your PCBs, but it's pretty rare to make an unsalvageable error here and also quite amusing if you do because a gigantic capacitor always looks funny to me. I should get out more.

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Re: Re:

Post by MikeDB » Fri Apr 02, 2021 11:15 am

Kawouddd wrote:
Fri Apr 02, 2021 6:47 am
decaying.sine wrote:
Tue Jan 18, 2011 11:24 pm
Resistors are the easy part. Just get all metal film 1%. They are cheap if you buy in bulk. I only get 5% (the tan ones, generally) for more obscure values that don't have 1% readily available.
N00b question.

So, with wattage and resistance matched, is it fine to sub in some Tayda 1% metal film resistors in a project where almost all other resistors are 5% carbon film? [having browsed the last two pages, fairly sure this is yes.]
Carbon film resistors are for noise generators, and they're not even very good at that :-)

If you're intending to do DIY long term, I would suggest you get two assorted packs of 10 or 25 each of 1% metal film resistors, one of all E24 values and one of all E48 values, from whoever is your preferred supplier. Resistors cost almost nothing in those quantities and by buying both packs you'll have every conceivable value you'll need, and more of the common values like 1k, 10k, etc.

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Re: Knowing How to Source Components

Post by Kawouddd » Fri Apr 02, 2021 11:29 am

cygmu wrote:
Fri Apr 02, 2021 9:46 am
Those specs will be fine.

Metal film resistors are in most respects superior to carbon film and 1% tolerance means they are meant to be closer to the nominal value than 5% tolerance, so the circuit will operate more closely to the "ideal", whatever that means. As for power ratings for resistors, you don't have to pay much attention to the difference between 1.8W, 1/4W etc for most values: anything above 4.7k cannot possibly be required to dissipate more than 1/8W in a circuit powered by +/-12V (power = V^2/R, V is 24V max) and it is pretty unusual to have 24V right across a resistor.

Likewise for capacitors, anything with a voltage rating 50V and up is pretty robust to the voltages you'll see in your synth.

Sometimes as power rating or voltage rating increases the package size of the part also increases so it might be worth making sure the parts you are buying will fit your PCBs, but it's pretty rare to make an unsalvageable error here and also quite amusing if you do because a gigantic capacitor always looks funny to me. I should get out more.
Phenomenal. Thank you. And thank you too, MikeDB!

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Re: Knowing How to Source Components

Post by Kawouddd » Sat Apr 03, 2021 12:23 pm

I am down to the last three components on a BOM.

652-RLB9012-103KL
RLB9012-103KL
10000uH 10% .17A
Bourns Fixed Inductor


665-AS06608MRR
AS06608MR-R
.5W 380-7500hZ SLDR
PUI Audio Speakers & Transducers


161-164SP-EX
Snapin Mnt Mini Jack
Kobiconn Phone Connector


Delivery times are between the back end of May and late July (speakers). I could source the fixed inductors from China / Arrow (or the US), but at $36-45 on 3 or a minimum order of 40 respectively.

I suspect at this point it makes sense to crack on with the build and see where I end up - are there any secret repositories of stock I might be missing, or places that are worth a scout?

Thanks!

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Re: Knowing How to Source Components

Post by cygmu » Sat Apr 03, 2021 1:14 pm

You can surely obtain equivalents from UK sellers (RS, Farnell, Rapid).

For the inductor, look for a 10000uH (or 10mH) inductor which can handle at least 170mA and fits the PCB, assuming it goes on a PCB.
The speaker and jack look like they are wired rather than PCB mounted, so find any panel-mount minijack and any 0.5W speaker with similar impedance (6 - 8Ohm) that will fit whatever panel or enclosure you have or plan on making.

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Re: Knowing How to Source Components

Post by KSS » Sat Apr 03, 2021 2:08 pm

cygmu wrote:
Fri Apr 02, 2021 9:46 am
Likewise for capacitors, anything with a voltage rating 50V and up is pretty robust to the voltages you'll see in your synth.
For some types of capacitors there is more than power rating to be concerned about. Because their capacitance changes with applied voltage. So even though your capacitor can handle 50 volts, it might have a capacitance of half is rated value well before that voltge is reached. It won't burn up, but it's not doing the job it was intended to do.

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Re: Knowing How to Source Components

Post by Kawouddd » Sat Apr 03, 2021 3:16 pm

cygmu wrote:
Sat Apr 03, 2021 1:14 pm
You can surely obtain equivalents from UK sellers (RS, Farnell, Rapid).

For the inductor, look for a 10000uH (or 10mH) inductor which can handle at least 170mA and fits the PCB, assuming it goes on a PCB.
The speaker and jack look like they are wired rather than PCB mounted, so find any panel-mount minijack and any 0.5W speaker with similar impedance (6 - 8Ohm) that will fit whatever panel or enclosure you have or plan on making.
That’s hugely useful. Thank you. So all I need to be aware of for the inductor is the microhenries, the 170mA as a *minimum*, and the footprint?

I am very much building by numbers, working on the principle that I will learn by doing. Much learning has not yet been reached!

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Re: Knowing How to Source Components

Post by cygmu » Sat Apr 03, 2021 4:50 pm

KSS wrote:
Sat Apr 03, 2021 2:08 pm
cygmu wrote:
Fri Apr 02, 2021 9:46 am
Likewise for capacitors, anything with a voltage rating 50V and up is pretty robust to the voltages you'll see in your synth.
For some types of capacitors there is more than power rating to be concerned about. Because their capacitance changes with applied voltage. So even though your capacitor can handle 50 volts, it might have a capacitance of half is rated value well before that voltge is reached. It won't burn up, but it's not doing the job it was intended to do.
Haha, absolutely right, and in fact I drafted a whole paragraph about this in my post above and then deleted it because it was getting too nuanced for the purpose. When learning this stuff, the huge amount of information around can be intimidating so I decided to leave it out -- but I think this post is a nice breadcrumb to lead to the next stage of learning when the time comes.

That said, (and this is for Kawouudd because KSS already knows!) there is another thing that is important when substituting capacitors: the dielectric. Caps come with a code that looks like "X7R" or "Y5R" etc which describe their capacitance variation with temperature. One to look out for is C0G or NP0 which means no variation with temperature. C0G/NP0 caps are very close to ideal capacitors and when they are specified, you should not substitute them with an X7R etc.

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Re: Knowing How to Source Components

Post by cygmu » Sat Apr 03, 2021 4:53 pm

Kawouddd wrote:
Sat Apr 03, 2021 3:16 pm
That’s hugely useful. Thank you. So all I need to be aware of for the inductor is the microhenries, the 170mA as a *minimum*, and the footprint?

I am very much building by numbers, working on the principle that I will learn by doing. Much learning has not yet been reached!
Yup. This is why I think Mouser BOMs are less useful than traditional BOMs which list the parts together with the necessary specifications, e.g. "47pF C0G 50V 5mm lead spacing" rather than 810-FG28C0G1H470JNT0. The Mouser number is a result of the designer searching for the spec they want, but does not tell you what they were looking for.

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Re: Knowing How to Source Components

Post by Kawouddd » Sat Apr 03, 2021 5:56 pm

Thank you! I’m sure I’ll get there. The more building I do, the more I’m aware that I want to know what I’m building and why. I can now build a frequency central module from the pcb (or the ones I’ve seen!) but I still don’t know what’s doing what, and why.

Really appreciate this help! Properly loving building - I’m not sure I’m building anything coherent, but it is phenomenal to put things together and see them work!

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Re: Knowing How to Source Components

Post by KSS » Sat Apr 03, 2021 7:25 pm

cygmu wrote:
Sat Apr 03, 2021 4:53 pm
This is why I think Mouser BOMs are less useful than traditional BOMs which list the parts together with the necessary specifications, e.g. "47pF C0G 50V 5mm lead spacing" rather than 810-FG28C0G1H470JNT0. The Mouser number is a result of the designer searching for the spec they want, but does not tell you what they were looking for.
This! 100% this. :agree:

Here's a fish vs. How to fish.

--------------------------
No ill will intended to the OP who has already said he's learning by the numbers. But this point of cygmu's cannot be over-emphasized.
As we're all finding out since the pandemic has exposed the cracks of the component infrastructure and mfg. JIT practices. <--It's going to get worse before it gets better.

Better learn how to source by 'fishing'; the fishmonger's sheltering at home.. Probably chopping up his own lettuce and dicing his salad fixings too.

--------------------------
@cygmu: Yeah, I get it. Long replies are not always taken so well. As you know, I tend to choose to err on the side of too long than too short. ;)
Treat utility modules as stars instead of backup singers.
Treat power supplies like Rockstars instead of roadies!
Chase magic sound, not magic parts.

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Re: Knowing How to Source Components

Post by Kawouddd » Mon Apr 05, 2021 6:44 pm

I have just spent 3-4 hours identifying ordering the materials from BOMs for 7 or 8 ciat PCBs, and feel both utterly worn down and trivially more informed / knowledgeable!

I strongly suspect that about ten things will turn out to be wholly inappropriate 😂

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Re: Knowing How to Source Components

Post by Kawouddd » Wed Apr 07, 2021 12:04 pm

I have just realised that I have failed to source c.100 NPN transistors with a Mouser lead time of 8 months.

The component is BC546BTA, with HFE/450.

There are two alternatives available, HFE/800 and HFE/220, otherwise identical in every respect.

I think - from a bit of reading - that the 800 is likely to be the better bet, but either will probably work. Any thoughts?

Thanks!

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Re: Knowing How to Source Components

Post by EATyourGUITAR » Wed Apr 07, 2021 11:55 pm

Kawouddd wrote:
Wed Apr 07, 2021 12:04 pm
I have just realised that I have failed to source c.100 NPN transistors with a Mouser lead time of 8 months.

The component is BC546BTA, with HFE/450.

There are two alternatives available, HFE/800 and HFE/220, otherwise identical in every respect.

I think - from a bit of reading - that the 800 is likely to be the better bet, but either will probably work. Any thoughts?

Thanks!
I looked into this for you. the suffix B indicates a max gain of 450 Hfe. any BC546B from any brand is correct.

https://www.mouser.com/datasheet/2/395/ ... 918116.pdf
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

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Re: Knowing How to Source Components

Post by Kawouddd » Thu Apr 08, 2021 1:31 am

EATyourGUITAR wrote:
Wed Apr 07, 2021 11:55 pm
Kawouddd wrote:
Wed Apr 07, 2021 12:04 pm
I have just realised that I have failed to source c.100 NPN transistors with a Mouser lead time of 8 months.

The component is BC546BTA, with HFE/450.

There are two alternatives available, HFE/800 and HFE/220, otherwise identical in every respect.

I think - from a bit of reading - that the 800 is likely to be the better bet, but either will probably work. Any thoughts?

Thanks!
I looked into this for you. the suffix B indicates a max gain of 450 Hfe. any BC546B from any brand is correct.

https://www.mouser.com/datasheet/2/395/ ... 918116.pdf
Heartfelt thanks. How on earth did I manage to spend three hours searching for transistor substitutes without finding identical specced other brands?! 🤦‍♂️ Yet with your comment, thirty seconds on eBay (low value order) and sorted. Thank you!

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