I’m looking to get back into electronics and planning to do so via modular synths. The combo of both analog and digital is appealing, as are the low signal rates making for easy DSP later. I studied ECE in college so I’ve got some electronics and signals knowledge, but I haven’t applied them much due to going into software after.
To start, I’m planning to build some analog modules, and I’m trying to figure out what I should stock up on for prototyping. I don’t particularly care about reproducing old circuits, but I want to be able to put together a variety of practical circuits that use modern materials and chips. I have some of the tools I need already, like a couple breadboards, soldering iron, hookup wire, oscilloscope, multimeter, etc. and will add some others, but that’s a separate task.
To that end, I’m trying to figure out what to stock up on for making prototypes. Ideally some of these parts could also be used in designs for actual use, like there’s little point in buying special pots just for prototypes when they could also go in a panel. Budget is not fixed but I’m expecting this all to come in around $400. I’m currently thinking that I want:
A collection of 1/4W resistors, at various tolerances, including some which are fairly precise (.1%?) and low-thermal coefficient. 47 to 4.7M should cover pretty most of what I’ve seen in audio circuits.
A collection of capacitors. These break down into power handling (uF) and signal path (mostly pF). Power caps could be cheap electrolytics, maybe? Or ceramic. Signal path should be low temp coefficient, probably C0G.
Some trimpots. Linear, log? Anywhere from 200-200k max value.
Some non-trim pots for controls. Log and linear, and probably only have to cover the 10k to 100k range. These tend to be expensive ($x.xx not $0.0x) and are big, so a narrow range is nice to be able to not get 100 of them.
Chips! Most of these should be per-prototype sorts of orders, like an AS3440A for a VCO, but some seem pretty generic like op-amps. Op-amps differ in supply voltage, input voltage, power and current limits, and some non-idealness params. I have no idea which of these to buy. Probably also some power regulators like LM7805, but I see there are also some precision voltage reference regulators used sometimes like the LM4040 series (e.g. the LM4040AIZ 4.1 in the 1222 VCO). OTAs? Transistor pairs? What’s worth stocking vs ordering as-needed?
LEDs
I thiiiink that gets me enough to breadboard up some circuits? Will need to add sockets and perfboard/stripboard to make something to keep around longer, or get some PCBs made. I’m fond of PCBs but I suspect the intermediate option will be good to have.
Oh and if you have recommended kits for the above (e.g. 5 each of whatever capacitor value range), lmk! Not having to separately buy a container and sort things would be a plus. I’m in the US if it matters.
One way of finding out which components you are likely to need for your designs is to look at what is used in existing designs. Furthermore, you can often adapt a design to the components you already have. Quite a few signal processing schemes use a few opamps with some resistors as the processing parameters which you can change into a standard values like 10k or 100k without affecting the circuit’s working too much. Given the multitude of circuits you may want to build or design, it is difficult to suggest what to buy beforehand. Given that quite a few components come in sets of 10 or 100 you will gather quite a collection of components automagically after a few projects.
Why? I’ve never seen a synth circuit that requires that tolerance. Sometimes you need resistors that match at the 0.1% level, but it’s a lot cheaper to just go through your 1% resistors with a multimeter and pick out matching ones.
The ones I use the most of are 100 nF for bypass, and those can be cheap ceramics. In signal paths I use a lot in the 1 nF– 1 µF range, and those are usually film. Though for breadboarding I’ll grab a ceramic if the film isn’t readily available, it won’t make that much difference.
I don’t think I’ve ever used a log trimpot. Not even sure where to get one.
1M are useful sometimes.
TL07x are about 97% of the op amps you see in synth circuits.
LM4040 is a voltage reference, not a regulator. Use it when you need a precise voltage but don’t need it to supply much current.
LM13700 is in a lot of designs; unfortunately the through hole version is out of production (at least outside of China).
For prototyping, hand matched single transistors may be good enough; if you really need a pair, might be best to order it for that specific project. But I don’t see single transistors on your list. 1N3904 is used a lot, 1N3906 less so.
I got started a bit over a year ago from zero experience, so I had to do a fair amount of stocking up, to the point the first six months were pretty discouraging, as every build would be stopped in its tracks due to my lack of stocks.
Every time if i saw a thing come up in two separate schematics, i’d just buy a whole bag.
I ended up buying a bit of stuff I didn’t need, but not that much.
Things I personally consume like candy:
Jacks
B100K pots
1K, 10K, 100K resistors
100nF & 1µF (ceramic) and 10µF (electrolytic)
TL072 & TL074 (get a reputable source, they get cloned)
1N4148, 1N5817
2N3904 & 2N3906
Pin headers (i like to wire wrap a lot)
Perfboard and breadboard-layout protoboards (unlike most people here I do not like stripboard)
I use an Excel sheet to organise my electronic components and plan and keep track of my very next projects.
I really like it since I can add new rows for each project, dial in the number of required items for each component and then I can set that planned counter to how many I want to build and it I immediately shows the missing components (and counts) in red by multiplying the required amounts and subtracting them from the stocked amounts. This makes planning the next order at Mouser/Tayda/Reichelt/Wherever much easier… of course you need to do some inventory here and there and correct the stocked numbers (when prototyping, I don’t constantly update the sheet), but it’s a very good overview and saved me a lot on shipping costs in the past years
I think that having such a thing is really helpful when you start since you automatically get an overview which parts are needed.
I agree with @AriaSalvatrice’s selection/collection, because it matches what I seem to have most of. I like to build on perfboard, and usually I can do it with components I already have.
I started with a kit of 1/4W resistors. Later I completed the E12 series in the 10k and 100k ranges, because those are mostly the ones you need for setting op-amp gains.
For everything else, I bought 2 extra of anything (capacitor, transistor, IC etc) that appeared in a circuit I wanted to build. If I run out of a particular item, I buy 10 (or whatever gets the quantity discount).
I have a vaguely similar spreadsheet too, and using that I’ve extracted a sort of kind of list of the parts I have used most often (mainly for assembling, as well as for prototyping), for what it is worth, which is not much:
#
Part
255
Resistor
100k
236
Resistor
1k
233
Jack
1/4" vertical
216
Capacitor
100nF
ceramic disk
164
Resistor
10k
135
Diode
1N5817
101
Capacitor
10µF
electrolytic
82
Molex
Crimp terminal
78
Molex
Connector 2 pin
75
Diode
1N4148
74
Molex
Header 2 pin
72
Header
10 pin shrouded
69
Resistor
47k
63
DIP socket
14 pin
54
Transistor
2N3904
TO-92
54
Op amp
TL074
DIP
49
DIP socket
8 pin
46
Resistor
22k
45
Resistor
1M
43
Knob
MF-A01
6.35 mm
38
Resistor
20k
35
Potentiometer
B100k
16mm dia, panel mount, 6 mm shaft
35
Op amp
TL072
DIP
31
Resistor
10k
1/8 W metal film
31
Toggle switch
SPDT panel ON-ON
31
Knob
MF-A01
6 mm
30
Resistor
1.8k
30
Resistor
2k
30
Resistor
2.2k
27
Resistor
470R
27
Resistor
4.7k
26
Capacitor
100nF
0805
26
Resistor
100k
0805
26
MF-A03
knob
6 mm
25
Resistor
220R
25
Resistor
30k
23
Transistor
BC547
TO-92
21
Diode
1N4004
21
Potentiometer
B100k
9mm dia, PCB mount vertical, 6.35 mm shaft
20
Capacitor
1nF
polyester
20
Capacitor
10 nF
polyester
20
LED
green
5 mm
Except where noted:
Everything is through hole
Resistors are 1% metal film 1/4 watt
As for why I list four more Molex connectors than headers, good question.
Wow, thanks to everyone for all the great advice! Here’s my current planned changes:
1% resistors, not .1%. There aren’t many .1% through-hole options anyway, and 1% metal film ones have the desired noise characteristics. E3 series values only, I can put them in series/parallel to prototype and buy exact values as needed. Maybe I’ll fill out the E24 values in the 1k and 10k decades at some point.
Diodes! P-N (1N4148 for now, 1N4001 later if I build my own AC adapters), Schottky (1N5817)
Opamp parts: TL072/4 for now, will experiment with other options later when I have something I think would benefit
Multiturn trimpots. 1k, 10k, 100k, 1M. 10 of each because that gets a discount. Looks like the Bourns PV36 series is cheaper than the 3296 or 3266, and seems just as well specced - according to Anyone using Bourns PV36 Trimmer Pots? - MOD WIGGLER they were originally a Murata part.
Larger pots. A100k, A1M, B100k, B1M. Probably just a couple of each since these are going to get re-used. Will buy as needed for building.
Capacitors. AFAICT the pF values are mostly for compensating op-amps, and TL074 are internally compensated.
Ceramic: 1, 10, 100nF. Plan to adjust R for RC filters and buy more later.
Electrolytic: 10uF 35V
A couple 1/8" jacks for connecting to speakers off the breadboard.
I saw one in I think it was a Buchla circuit in Lanterman’s YouTube series on analog electronics for music synthesis, so they at least once existed. Looks like Piher/Amphenol makes some, if you should ever need them. https://www.piher.net/wp-content/uploads/PIHER_PT-10_PTC-10.pdf
Ugh Mouser lists this with a photo of the SIP package, but now I see that they’re actually SOIC16 package. Thanks for saving me from buying some difficult to use chips. Looking at Mouser, there’s no through-hole OTAs listed at all, only SOIC, SOT, MSOP, all of which would need an adapter for breadboarding. Are there any OTAs available in through-hole packages? Will I need these for modern designs, or only historical ones? Looks like they can mostly be replaced with other parts with some minor other circuit changes, especially those used in a linear range.
This is approximately my plan as well, though I’m hoping to shortcut looking at a bunch of schematics by coming here.
Do you have a sense for how often you buy 2 and then never run out?
It’s pretty much the only OTA I’ve seen in synth circuits (other than the even-more-obsolete LM13600 and CA3080) and yeah, pretty much the last OTA in DIP packaging. Barton’s DIY designs are 100% through hole, but they’ve switched to SMD LM13700. You can find them, or things alleged to be them, on eBay and AliExpress, but caveat emptor. Speculation that maybe Alfa would produce a DIP clone has so far proved wrong. There’s apparently one Chinese company producing and selling them, but they’re pretty much an unknown quantity. You may just have to learn to solder SOIC. I mean, it’s not THAT hard (says the guy who’s done it about four times, and has 19 DIP LM13700s left in his stash).
Once upon a time I modded PlayStation 2s for friends at college so they could run Japanese games. That involved soldering 15-30 (later generations of mod chips had fewer) tiny wires to .5mm pitch QFP parts. I think I got up to about a 70% success rate on the full mod. Fortunately the local GameStop had a $20 no questions asked warranty on used systems.
It’s been a while and my eyesight is worse now, but I also have magnifier lights now and didn’t then, so hopefully I’ll be able to manage 1.27mm pitch pin to board connections when it comes to it. Or there’s always the toaster oven option.
Everyone has given you great advice, but just to throw in my experience…
I bought a couple of packs of the metal film resistor and polybox capacitor kits from bitsbox here in the uk. There’s cheaper options but I have found both to be continuously useful. If you’re not in the uk I’m sure a local shop does something similar.
I also bought a trading card storage folder (the thing you see baseball or Pokémon card collections stored in) and use that for storing components. I have it set up so page 1 is 1-10r, page 2 is 10r-100r, page three 100r-1k, then 1k-10k… etc. It’s a real time saver to be able to flick through it quickly, and took no time to set up. Found it better than the drawers because you have more slots.
Interesting (i.e. odd, I think) choices from Bitbox. For the 230 piece carbon kit, it’s all the E6 mantissas except 15. For 480 piece carbon, it’s E3 (10, 22, and 47). 1080 piece carbon is all the E6 mantissas plus 56. 1440 piece carbon is E6 plus 56 and 82, except they add 2.7M and leave out 6.8M and 8.2M. And the metal films are E6 except 15 and plus 56.
The only E12 in my top 20 most used resistor values are 1.8k, 120k, 18k, and 12k. Not the 56 and 82 mantissas Bitbox seems to like. On the other hand, E24 2k and 20k are in my top 10 — and 30k is in the top 15, but that’s because of one project that used 11 of them.
Skala’s observation is that the kits usually have lots of values under 100R and few if any values above 1M. The former are rarely used in synth circuits (except 10R, if you’re the sort of person who uses them for fuses) and the latter are used more. Among the Bitbox kits the 230 piece carbon is the only exception to the first observation and the 1440 piece carbon is the only exception to the second.
I think its a very hard thing to do, to know what you need to start building projects, I think your stock grows as you buy parts from BOMs and a gut feeling. I have a wall of drawers with capacitors, resistors, pots, switches, displays, SOCs, relays, basically you name it and I’ve probably got one or two kicking around and I’m still running out of parts.
Not really, but it’s a nice surprise when I find them again.
All those sad little £0.06 ceramic capacitors lurk unloved in their ziplock bags while their flashier-looking polybox cousins go to all the balls. Then one day their big moment comes: only they can fit into the golden slipper.
I am doing similar to you in getting back into EE through Eurorack–just started a couple months ago. I have found the assortments of components available on Amazon to be super useful. They’re $20-30 each and you get a nice broad spread for starting out. When you end up running out of something before everything else you know you need to order a big bag of that for the future. I would get:
Resistors, asst, 1/4W 1% (for audio quality)
Caps, ceramic, asst
Caps, electrolytic, asst
Caps, metal film box, asst (optional, but tighter tolerances for audio circuits)
Transistors, NPN 3904, order a whack of 50-100 from a supplier.
Transistors, PNP 3906, you need about half as many as the NPNs.
Transistor pairs? Buy them as-needed.
Diodes, standard signal ones, 2N4444 or similar, get a whack of these too. You might also consider done general purpose Zener and germanium ones as they’re called for occasionally.
Look at the ICs used in the kinds of modules you want to build, but:
TL072 (dual)/TL074 (quad) op amps. Get maybe 25 of the 074 and 15 of the 072.
Save the OTAs maybe for later (plus, they’re a pain, as pointed out, bc they aren’t available in DIP THT packages anymore which makes using them on a breadboard a pain).
40106 hex Schmitt trigger inverter. Get 5-10.
555 timers, maybe?
Voltage regulators–order as needed.
There are some other 7400 and 4000 series chips you might find useful–counters, shift registers, logic gates, etc–but not necessary. Get them as needed for specific modules.
Since you said you’re interested in the combination of analog and digital you might consider getting some kind of microcontroller like an Arduino Nano.
An assortment of LEDs
Wire. Loads of wire. Stranded and solid, both about 22AWG (not sure how that translates to metric off the top of my head). Solid core for using on the breadboard, or buy a kit of the pre-measured ones. Get two kits–you always run low on the short pieces.
I grabbed a bunch of male-end Dupont wires for breadboarding. I also got a kit for making your own Dupont and JST cables–make sure the kit you get is compatible with the wire gauge you intend to use.
POTS! I found an assortment of values that included audio/log (A), linear (B), and reverse log (C) tapers. They’re panel mounts, but their leads also fit into a breadboard. Buy more of the ones you find yourself using the most. You might prefer to get a different footprint for when you move to a permanent PCB, up to you.
Trimpots, find an assortment.
Jacks, 3.5mm or 1/4" by your preferred format. All switched, or maybe half switched and half not. Get loads. Same deal as the pots with footprints and perm builds.
Buttons (get ones that are both NO and NC depending how you wire them), switches (almost always DPDT is more useful), etc.
Standoffs or other hardware for mounting your final board to a panel.
Pin headers for power connections and stacking PCBs together.
That’s probably enough for now. LOL
OH! Almost forgot: don’t just buy stuff willy-nilly, pell-mell, or helter-skelter. Have a plan for his you intend to put it all together at the end. That’ll really inform what your going to need.
So, as someone mentioned elsewhere, as we move into the future, more and more components are going to be available in only SMD packages. I’m the shirt term you can get SMT breakout boards that you solder an SMD component to and then use pin headers to convert to through hole.
It might be worth considering, if you’re going to be designing your own boards and sending them to a fab house, to design them to use SMD parts when possible since it means you can make them smaller to fit in your rack.
But, yes. Learning to solder surface mount parts is a worthwhile endeavor, and one which is on my own Big List Of Skills To Learn.
Less than half. I’ve used them in a ratio of about 5:1
That’s a rectifier diode. The usual signal diode is 1N4148.
I’ve used germanium only once, for a ring modulator, and that only for tradition’s sake, Schottkys might have been better. Schottky diodes such as 1N5817 are used a fair bit. I haven’t used Zeners often, probably best to get those as needed.
I’ve used a grand total of one. Buy as needed, unless you know you’re going to be building a lot of circuits that will use them.
A few of those would make sense.
I’d even consider stranded and stranded and solid. Silicone stranded and PVC stranded. The former is very flexible and that can be very welcome. Or not, because I find trying to push silicone wire into a Molex connector, for instance, is an exercise in futility — it just bends. So for those situations I use PVC. For all these flavors there are kits of 6 colors available. You can skip the pre-cut solid wire if you want to save money, just get or print a lead bending tool and make your own.
I don’t think I’ve ever needed a NC push button. (Installed one by accident once, though. Took forever to figure out the problem.) For switches I almost always use SPDT. Granted you could use a DPDT and just not wire the second pole, but DPDT is larger and probably costs more. SPST on the other hand doesn’t really have much of an excuse versus SPDT.
