Building up components inventory - how to do DIY without always buying full kits???

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neopl
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Building up components inventory - how to do DIY without always buying full kits???

Post by neopl » Fri Jun 19, 2020 8:31 pm

Hello all,

I'm wondering how some of you do DIY projects. I've only done one in the past, the Hades DIY synth, but now that I started my modular journey, I would like to make many modules my self. Considering that I am in this for the long haul, I would like to take advantage of being able to buy the much cheaper PCB and front panel only sets (instead of the much more expensive full kits).

My question is this, how do you manage to not buy full kits? Are you all electrical engineers with a ton of components sitting around waiting to be used, or have you employed conscious effort over time to build up a component stock at home? Or do you buy PCBs and then on your own purchase all the required parts?

Considering that this modular journey will cost a pretty penny, I would like to save where I can, considering that I enjoy DIY, I would, if at all possible, like to save here too, but I am not sure of the best approach to take. I know that buying full kits is already cheaper than buying assembled modules, but I would love to have the freedom of just buying PCBs and being comfortable with what to do next.

Any thoughts?

Thanks!

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by Whelm » Fri Jun 19, 2020 9:27 pm

I'm far from an engineer and I source my own parts. It does take a bit of learning. Be especially wary of the voltage rating of capactors and the wattage of resistors.

What I do and what I would recommend is that you pick a PCB or two that you want to build, CAREFULLY document all the components you need for them, then buy all those components. Things like resistors and capacitors and other common parts you can get extra. Knowing the types of things you're likely to want stockpiles of though can take a bit of experience.

Generally you get price breaks at certain quantites. So if you need two 200R resistors, for example, you may as well get 10. If you need 18 10K resistors, you may as well get 50. You can stock up on 0.1uF capacitors and 10uF electrolytics. You can stock up on 1n4148 diodes. But just generally I'd say see what you need for what you intend to build and get extras. Over time you'll develop an inventory as well as a sense of what is worth having in reserve.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by Schlumpfhut » Sat Jun 20, 2020 12:59 am

In terms of resistors you can buy certain values like 1k, 10k and 100k in bulk as you are running into these in basicly every project. Trimpots and presets of certain values are also quite common. And IC sockets and standard ICs like TL07x.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by latigid on » Sat Jun 20, 2020 1:04 am

I tried the "combined BOM" approach of pooling several kits' worth of parts and doing one big order but the result was a lot of parts in bags and quite a few unfinished modules. It's easy to say "just wait for one more PCB and then I can save time and money on parts ordering" but in hindsight I think it's a fallacy.

Two approaches:
1) Similar to @Whelm/@Schlumpfhut : when you buy parts for a project, bump up the quantities of "common values" to 10/100, so decades of resistors/caps 1xx 22x 47x, for 10/100/1k/10k/100k/1M (within reason), 100n caps especially, 1/10/25/50/100k pots, common choke beads, 4148 diodes, common transistors (3094/6), common opamps (TL07x) etc. etc.

2) Don't go for a common pool of components, rather get what you need for a given project. You are much more likely to finish something if everything is at hand in one place, such as the box it was delivered in. If you have draws full of stuff, the effort of going though hundreds of components might be enough to put you off.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by teleport » Sat Jun 20, 2020 1:24 am

I'd recommend first considering and focusing on a number of projects that you intend to undertake in the foreseeable future - study their BOM's and look for identifiable patterns of parts that are common. This can provide a sort of statistical wedge to fight back with some reasonable predictability against the seemingly infinite variety of components, (it's bewildering when you're first familiarizing but over time patterns will come into focus).

First thing you're likely to observe is that passive components called for typically fall into predictable values (rather than being a random and infinitely subdivided distribution) - these are the E-Series number values https://en.wikipedia.org/wiki/E_series_ ... d_numbers
A reasonable starting point is to accumulate a kit of resistor values particularly populated towards those parts which have these numbers - they will appear frequently. (that's not to say that oddball values don't exist, but it's vanishingly rare, designs and designers will vary on this count somewhat).

For active components similar rules hold - study all the designs that interest you and look for commonalities, the transistors, op-amps and diodes that are common are used over and over in many designs, the synth DiY world has been self referential for ages. If you happen to be focusing on multiple designs from the same designer, you'll get even more mileage from this approach.

If your situation affords it - the opportunity cost approach to parts buying often makes good sense - knowing that anything that needed now implies a greater likelihood of future need - so increasing the qty proportionately factoring that estimation, (and of course always accounting for spillage and magic smoke leakage - Murphy's law and all that). Solving these problems effectively will surely lead to the next important problem of effective storage and organization, depending on how deep you want to go this can wind up taking over a fair amount of real-estate, at a certain quantity of parts a fair bit of structure will be the only thing keeping things sane - so planning a few steps ahead there is a good idea too.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by KSS » Sat Jun 20, 2020 5:34 am

Choosing to work with a certain designer or only a few will help. Befaco for example offer all manner of designs. When you buy in to a designer's output, you're also buying in to that designer's favorite parts. Dustin of Stroh Modular is another. CGS. CLee and Michael Barton. Each have their own way of doing things.

And that matters today *far* more than it did in years past! Even five years ago, I'd have answered like the others above. Get the basic R's and C's and pots and jacks, IC's, etc. And go for it.

But not now. At least not if you're buying PCB and panel. The shift to small HP euro and SMD and parallel 'panel' PCBs make it all a lot less secure in getting a bunch of parts ahead of your builds. Because the jacks for a TTSH won't work in most of the small PCBs needing Thonkiconns. And the TH decoupling caps you could in the past expect to go throough with every build, may now be SMD, even if the rest is TH. Are you getting the right tall trimmers? 9mm pots?

When we were all doing fly wires and making our own panel designs the common' parts stash had a lot more comformity. 16mm Alphas handled the pots. 1/4w, 1% metal films handled the R's. Cap then were like now; you gotta get the right ones. Size matters! L/S matters! It's not enough to get the right values, or even the right dielectric type if it won't fit the board.

Buying in bunches to begin used to work. That's just not the case anymore. Those above who said be careful not to get too far ahead of yourself are correct.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by Spastic_Colon » Sun Jun 21, 2020 2:11 am

I built up a decent catalogue of parts from starting out sourcing BOMs for ST Modular builds. I’m not electrically trained. Sourcing components, and nailing down a soldering technique has been self taught with a few pointers from the Facebook community

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by EATyourGUITAR » Sun Jun 21, 2020 10:58 am

I am not an electrical engineer but I am dumb enough to spend over $1000 on resistors capacitors transistors IC etc. .mostly to store them for years at my own expense. There are advantages and disadvantages. If you build everything as a through hole handmade prototype then there are reasons to stock up. You could build a vintage Moog on protoboard exactly like Moog did but I think that has mostly been replaced by surface mounted DIY. The best thing to spend money on is $10 for a 10 pack of PCB's. Buy mouser parts monthly. Stick to it. Have multiple projects going at once to stay busy if one of them is wait for parts. If you only buy parts for that one project. The PCB and parts is < $100 to build 10 of them. This is much cheaper than trying to manage an in house stock. I have about 100 hours spent doing inventory over a 10 year period. I didn't even make any money.
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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by transistorresistor » Sun Jun 21, 2020 12:53 pm

when you are starting out just look at the BOM and if you need one resistor buy ten, common parts that are inexpensive often come w a small quantity discount and its good to have extras laying around anyone if you make mistakes or have failures. over time you'll have a good stock of common items on hand and your parts orders will get smaller for more specific parts needed for the next project. This is only economical if you plan to be building stuff all the time but one day you wake up and will never have to buy a 10k resistor again ;)

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by Bartimaeus » Sun Jun 21, 2020 1:01 pm

as others have said, every time i build a module, i buy extra of each component. if it's passives like resistors, i'll buy between 30 and 100 of that value (still less than a dollar). i use tayda for passives which makes it even easier and cheaper. for ICs maybe i'll buy 10 if i only need 1 or 2 for the module. most modules use similar parts and values, especially if you build stuff from the same companies. manhattan analog modules have a lot in common, so you can buy a bunch of ferrite beads and fuses to get bulk discounts, and build a ton of their modules. of course, it also helps if you plan ahead to build multiple modules. it's easy for shipping costs to eat away at any savings, so it's worth it to order enough parts for half a dozen modules at once, even if you haven't bought the pcbs/panels yet.

it's more expensive upfront, but if you know that you'll build more modules in the future it's worth it. plus it cuts down on all those plastic bags with only a couple resistors in them.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by HZR » Mon Jun 22, 2020 3:54 am

When ordering i always order extra components

I have also ordered quite some assortments (resistors, capacitors) from wish/ebay. That helps a lot at the beginning

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by jimfowler » Mon Jun 22, 2020 10:04 pm

If it’s a cheap and frequently used part always order up to the minimum price break quantity. If it’s a 7 dollar switch and the price break is at 50 pieces and you save 13 cents per switch by ordering that many when you only need two don’t do it.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by neopl » Tue Jun 23, 2020 8:51 am

Thank you all for taking the time to go over all this. It would appear that a sensible approach is to just buy more each time, to take advantage of price breaks, and to build an inventory. Storage and organization has been pointed out, I must admit it is not something I thought of, but I will have to, clearly!

It was also pointed out to use ebay to build an inventory of some common components. I see that resistors can be gotten for quite cheap on ebay in bulk, but I am worried about quality. How important is quality in the more common electronics components? Is a resistor always a resistor, no matter where it is purchased or made? I know that capacitors can be either of good quality or poor quality, but how about some other components?

Regarding website where people purchase these components, I live in the UK, so I assume that https://www.mouser.co.uk/ is a one stop shop? Or are there others that can be recommended?

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by KSS » Tue Jun 23, 2020 4:30 pm

Double post
Last edited by KSS on Tue Jun 23, 2020 4:38 pm, edited 1 time in total.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by KSS » Tue Jun 23, 2020 4:37 pm

You're going to get a LOT of anecdotal responses to this question. I'll start by saying details matter. No, all resistors are *not* the same. When the worst are a penny and the best are a nickel, does it make sense to skimp?

But be especially concerned about the panel components and connectors. Cheap pots, switches, jacks and connectors are *NOT* the place to try and save money. Any seasoned synth tech will have many stories of connector problems, and you're literally in touch with each and every panel component! Their feel, quality, and lifetime affect you with EVERY use of your synth.

You're going to spend time and money to make this thing, don't sell yourself short. Changing out cheap parts -and finding problems they create in the first place!- is no fun. Well, actually it *can* be kind of fun. Until it isn't.

Spend some time and effort to get good at soldering using the tools and materials you've chosen to work with. Bad soldering practice hurts at least as much as poor component choices.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by Whelm » Tue Jun 23, 2020 11:24 pm

I wouldn't fuck with eBay for this stuff personally, who knows what you'll get and you're likely to get wrecked on the shipping anyways.

Mouser is reliable, if a bit expensive. It takes a bit of practice to learn to navigate their inventory but once you figure it out you can find 90% of the things you need. Don't forget to check the 'in stock' box and sort by price.

The downside to Mouser is the price. Especially for things like switches, Mouser will bankrupt you. See what you can get in terms of switches and pots and stuff from Thonk. If you need to save money, try Tayda. The general rule of thumb, such as it is, is that Tayda is great for passive stuff, on the cheap side for mechanical stuff like pots and switches, and some people have complained about the quality of their ICs although it's not something I've had trouble with. Tayda is considerably cheaper than Mouser, so if you're on a budget I'd definitely choose them over eBay.

I personally tend to stick to Mouser. Not sure how it is in the U.K but in Canada at least it's free shipping at $100, which is generally a few modules worth of parts. I have used Tayda in the past, particularly when I was living in the U.S, but getting hit with the additional courier fees from DHL (get fucked) when I had a package shipped to Canada sort of defeated the purpose.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by EATyourGUITAR » Wed Jun 24, 2020 6:38 am

ebay is good for tubes
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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by oudplayer » Wed Jun 24, 2020 2:09 pm

Recently I've had better luck recently with Newark/element14/farnell. They routinely have special pricing going on certain lines of components that are useful in a lot of synth projects; whereas Dale through-hole resistors tend to be about $0.10-$0.18 each in small quantities, I got a bunch for around $0.03 each so ordered a lot extra. Nichicon el-caps are often on sale, too.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by Bartimaeus » Fri Jun 26, 2020 11:19 am

For building an inventory of passives I'd recommend Tayda over eBay. I buy a fair amount from eBay these days, but it took a lot of buying to know what was a ripoff and what was good. With Tayda, you know almost everything will be at least solid. Plus some makers (like frequency central) include a Tayda parts list for their modules.

Mouser is indeed a good one stop shop.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by neopl » Sun Jun 28, 2020 2:51 pm

Thank you all for all the thoughtful responses. I definitely feel much more informed. I've never heard of Tayda so will be adding that to the list to sit alongside Mauser and Thonk.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by Val » Mon Jun 29, 2020 2:03 pm

I'm in the same situation, I've built a few kits and now sourcing parts

I only use Mouser (specific, ICs, good capacitors, switches, critical parts etc), Tayda (sockets, resistors, diodes, transistors, non critical parts), and Thonk (jacks, pots).

But on the contrary to what other said, I've gathered a dozen BOMs and ordering parts for all of them at once. But I'm tidy, have compartimented storage for all that stuff, Im not messy, and will build just by buying the PCB/panel when I want one.

I think that you organize yourself just like you feel it, if you want to order only for 1 project then do that
Take time to check specifications / datasheets on mouser. pay attention to capacitors dimensions sometimes.

as for the components, it depends on what you build, check the BOMs of the projects you're interested in, no need to stock TL07X opamps or 10k pots if you'll don't need them. Take your time

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by KSS » Mon Jun 29, 2020 6:52 pm

Sockets *are* critical parts. Talk to any synth technician about the value of *good* sockets.

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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by Eric the Red » Mon Jun 29, 2020 11:11 pm

I buy for one project at a time, for me “one project” is typically about 10-15 modules. And then I usually buy 10x of what I actually need so o have most of what I need for the next one.
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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by Matt_L » Wed Jul 01, 2020 3:13 am

I haven't been doing this for that long, I've built only like 15 modules or so, but it seems to me that most of the components are so cheap that bulking out won't save that much money. And whatever savings you might get from discounted prices from bulk quantities are likely entirely offset by ending up with a lot of parts you don't need.

And then there is the additional hassle of trying to sort everything and find the extra parts later for new projects. Just seems like a massive headache when instead you can just upload a BOM to Mouser, get all the parts at once and in one place. Even then, it feels time-consuming to track down the PCB, panel, and other miscellaneous parts that aren't in stock on Mouser.

For me, potentiometers and knobs end up being the most expensive components, though I haven't found bulk prices that make sense for me (like I said earlier, don't want to end up with $100 of a pot type that is hardly used).
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Re: Building up components inventory - how to do DIY without always buying full kits???

Post by EATyourGUITAR » Wed Jul 01, 2020 9:01 am

If you can't find it later, you buy twice. Parts storage game must be on the level.
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