I'm currently in my second year of studying electrical engineering, pic related is one of our projects from last semester that we did from scratch (just as a reference point). I talked to one of the profs and he has (inofficially) given me permission to use the facilities we have at the school if I want to.
My first idea is to make some effect pedals, I'm a bassist and I've already found freestompboxes.org , and there are quite a few schematics on there and a few fully traced boards as well. I'm interested in a compressor, a distortion pedal and a wah-wah, that's mostly it for now. We can make PCBs up to 100mmx160mm, double sided if necessary, and I'd have to hand solder everything (I'm decent enough at soldering).
Should I make something very simple to start with? I'd honestly like to do a copy of some of the really nice pedals out there, but they're more complex than what we've done before.
Design rules/things to keep in mind? I've never done something related to audio gear, are there specific rules that I need to keep in mind if I have to trace my own board? We usually do a ground plane like in the pic, avoid unnecessary/stupid routing decision, put suppressor capacitors as close as possible to the ICs, etc. Anything else to keep in mind? I'd post my attempts at the routed PCB here and on the mentioned forum, and probably check with one of the profs as well, but I obviously would like to know beforehand.
What specific pedal should I build? Maybe there are bassists or people with experience in building effect pedals here, I'd obviously like to build something nice that can compete with the things that are available on the market, but at a much lower price. Building a clone of a crappy distortion pedal that I could have bought for a few more bucks is not exactly what I'm after, if that makes sense.
Thanks in advance, any input is appreciated.
One thing to remember is that price!=sound quality. What are some pedals that YOU like? Do you have a distortion/comp/wah in mind that you would like to clone?
The best thing you could do right now is find a schematic for a pedal that you like and try to analyze it. For example, if you find a particular distortion pedal, look at the clipping arrangements and the filtering (really all that any "dirt" effect boils down to). One "gotcha" that guitar effects will have is that the inputs are typically very high impedance; modern practice is at least 1Mohm. As a result, the inputs to guitar pedals are particularly sensitive to noise. Add in the fact that any dirt pedal will have some gain to it and circuit layout becomes important. Make sure that the input and output are not close to eachother on the circuit board and you should be ok.
Also, I have found diystompboxes to be superior to freestompboxes, but both are good sources of information. Less swearing, no flaming, few arguments. More professional in general.
>>945253
>diystompboxes
I'll definitely check that out, thank you.
I know that price doesn't make the sound, but I'd rather copy something that's well reviewed and liked, and most of those effects are honestly in the 200€ range and not down in the 30€ bargain bin. Not to generalize of course, but that was my main reason for that comment.
I don't really have the option to test out a whole bunch of pedals sadly, so I'll have to go by reviews and recommendations basically. For the compressor I'd like something that doesn't colour the sound but CAN be cranked for a nice effect if I want to, so I guess I'll have to find the suitable comp and see if the schematics are available.
Thanks for the tips with the input jacks, I'll make sure to seperate them as much as possible on the circuit and physically as well (but sharing the ground plane shouldn't be an issue I assume? I don't see why it would but maybe I'm just missing something very obvious).
More research for me, basically, but thanks for the pointers.
Sharing the ground plane shouldn't be an issue. One compressor that people seem to like is the Engineer's Thumb. It uses an OTA in the feedback loop of the opamp. This gives you greater dynamic range; OTAs are fantastic devices but they are limited in headroom and linearity. Keeping it in a feedback loop solves those issues while keeping the benefits (well defined gain control).
In regard to testing pedals, do you live near any music stores?
>>945151
which pcb method are you using
watch over9000 youtube videos about it
then start with something EXTREMELY simple to get the process down.
next move on to making boards you actually want
personally i like to use copper-clad perfboard for designing one-offs
source a fellow EE good luck
>>945351
>In regard to testing pedals, do you live near any music stores?
Sadly, no. We really don't have many music stores left where I live and all the big ones are several cities away basically.
>>945371
We use FR4 boards with 35µ copper that are pre-coated with the photo-coating. I don't think that youtube videos or any simple practice pieces will be necessary, I've done it several times already in class and this time shouldn't be any different. As I said, I'll be able to use the facilities we have here and I could probably even get some help with a prof if something doesn't work out. But thanks for the input.
Okay, I looked up the required parts that I'll generally need, the connectors aren't an issue, I'll use a very simple metal or wooden box for it, resistors/caps/op-amps/whater I'll just buy as I need them, but the stomp switches that I find are ridiculously expensive. What are they generally referred to? I don't think they're supposed to be 20 bucks just for a switch.
This thing costs several hundred dollars if you buy it... Wow, yes I'll take that for less than 30 please. So, yeah. First clone should be a success, the schematic is validated and I don't see any glaring issues with my layout. Comments and tips are obviously very welcome, I'll probably order the parts and build it in a week or two. If that one's a success I'll move on to a compressor.
>>945377
>tfw 3rd year EE and never have had a pcb fab course :<
I've had to teach myself everything and we're a top 30 school.
>>946250
It's really not hard, and you'll probably never actually have to do it yourself as an EE, you'll just make a layout and send it off somewhere to have it fabbed. I guess that's why they don't teach it in some places.
>>946103
Stomp switches are generally expensive, but not $20 expensive. Try bitcheslovemyswitches or aliexpress or something. Also, if your enclosure isn't metal, line it with aluminum foil or something to keep it quiet. Metal enclosures act like a faraday cage which helps immensely.
>>946884
I found some for 6 bucks with 2 ON/ON switches (for true bypass without an LED indicator), that should work. I also found cheap aluminium cases, I'll have to drill holes for all pots, the switch and the input/output jack, but I'll be able to simply ground the entire case on a screw.
>>946241
Compare prices between a Klon Centaur and a clone's parts list if you want to shit yourself with rage.
>>946241
>several hundred dollars for two 2n3904s and a handful of resistors.
Fuck this gay earth.
germanfag here, what does EE mean? And what is an EE-Student?
>>947505
Holy shit, I didn't think it could be worse.
>>947518
The original uses one different transistor, but yeah that's 30 cents instead of 4 cents for that one. It's ridiculous how much the guitar crowd pays for certain things.
>>947523
EE = Electrical Engineering, that should clarify "EE-student" as well.
