I ordered it just now… I hope the PCB doesn’t smell too bad 
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I DID NOT REALIZE YOU CAN USE BOTH SIDES FOR ROUTES.
This makes it significantly easier! Third time I’ve got to this step with a board, but never further, that explains why. Thank you for the clarification!
Now I need to figure out how to add some graphics and I’ll send it off for testing!
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You’re also not using ground fills, so you have to route traces for ground, which makes it harder as well. The resulting tangle at the top is more than I want to try to puzzle out, but at the bottom the traces would be easier if you swapped the two Molex connectors around.
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@Sonosus - what process did you use to actually get the discount to apply? Getting the ALLPCB website to do what I want is a Kafkaesque task… it says Free on the landing page, then I sign up, but when I check out, the coupon only applies a zero dollar discount…
I registered and I thought something flashed by about emailing me a coupon code, but nothing showed up.
The reviews are… less than stellar
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Same thing happened to me. I’m starting to think this is too good to be true and maybe not legit. Perhaps the rules of the game should be adjusted from from ALLPCB’s “free” 100x150 to 100x100 for the JLCPCB prototype boards, which are only $2.
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Yeah, looks like all the positive reviews are fake and all the others are 1-star. I think I’m going to avoid this, don’t trust them with my credit card.
I send my order to JLCPCB! My first time getting a board made, I’m really excited! It’s a simple unity mixer that should fit nicely behind a 2.5cm Kosmo panel. I’ll share the files on GitHub once I can confirm it works (although it’s not an original design, I recreated it from a Barton Musical Circuits datasheet).
Thanks to everybody for the help! It’s crazy, less than a year ago I had never picked up a soldering iron before, now I’m laying out circuits and having custom made boards manufactured out in China! Wouldn’t have been possible without this inspiring community, I didn’t even know that would be possible otherwise.
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Hm, interesting.
http://www.bartonmusicalcircuits.com/4hp/unitymix/index.html
And certainly a good choice for a first PCB design, good and simple.
As a module design, I don’t know… since there are no attenuators and no gain control, if you put five signals in it seems to me you’re likely to get a whole lot of clipping out. Five 5 V signals added together with unity gain is 25 V and you’re not going to get that out of an op amp powered at 12 V! Run them through an attenuator module first and you’ll be okay, but I feel it’d make more sense to build attenuators into the mixer module.
(I’d also change the bypass caps to 100 nF, Barton’s the only designer I know who insists on using 10 nF; and as usual I’d replace the 10R resistors with 1n5817 diodes; and I’d follow Matthew Skala’s advice and change the 100k resistors on the second gain stage to 10k, but those are minor disagreements.)
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I think the general idea is to use only one or two inputs for signals that will go to v/oct, but up to all 5 for combining triggers and stuff. You wouldn’t want to have five of the exact same envelopes firing simultaneously, but you might want to combine envelopes with different shapes. For instance, if you have three slightly different envelopes combined then sent to the CV of a VCA controlling some white noise, you’ll get the 909 “clap” sound. Or, if you combine the (attenuated) output of an LFO and the output of the CV expression pedal, then run that to the CV control of a filter, then you’ll get an auto-wah pedal that you can control the intensity of. There are some other ideas here: 3 fun uses for unity mixers like Extra Mullet — Noise Engineering
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For combining short triggers, okay. But your “three slightly different envelopes” would need to be attenuated, otherwise the attack would almost certainly exceed the op amp’s output capability. Likewise in the article you linked, it seems to me the non-trigger applications would require pre-attenuation.
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I have used the free coupons for the past 2 months.
It is a little convoluted to use them. They show up under your account and when you go to use them the site asks for your gerbers.
They made the boards in 2 days and shipped the first set (which turned out to be 9 boards) via DHL and the second set (which turned out to be 6 boards) UPS. Board quality was fine. I’m working on my July submission.
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Yeah, I noticed that earlier, and a lot of the negative ones complain about unexpected extra fees…
Then I went looking at a competitor’s feedback to compare, and ended up reading a bunch of 1-star reviews from people with a visible review history that were literally complaining about everything under the sun, from luxury fashion brands via Chinese PCB fabs to local plumbers (“we cannot find you in our records, please call”), at which point I decided to clean the kitchen instead.
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It definitely works, otherwise I don’t know what’s in the DHL package currently leaving China
I’m on my phone atm but on mobile it’s under menu> my balance> coupon balance. I didn’t give them any details other than my address and Gerber files.
My first order from the 28th of June has shipped and the second order from yesterday is pending review.
They do seem more expensive than JLC with their standard service, but I won’t complain about quality seeing as the PCB is free.
Be careful, the claims of selling your email address might have weight even if they do give you the products.
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I use a masking service:
HTTPS://erine.email
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If they’re using DHL for their free products, we’re talking $100 or more per year just in shipping… That’s a lot of money for an email address. Cannot say I understand the business model here, tbh.
(I mean, JLCPCB and similarly priced fabs may sell their cheapest options near or at loss, but at least they pass the shipping costs on to you…)
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I do have a second address for use when I think it’s mainly going to used for spam, but gmail is good enough at spam filtering that I hardly worry about it in most instances.
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First order was DHL 2 day, second order was UPS 2 weeks. I also don’t understand their model but I’ll use it while I can.
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Googling around, there does seem to be some dubious activities/promotions coming from them. “Promote our service and get free shipping” is not the way to get a healthy user base - all it does is lead to spam and discontent.
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Number two! Slightly wider, but shorter so that it should be below the threshold for super cheap JLCPCB “prototype” boards.
Another BMC circuit, the Full Wave Rectifier, but modified to use LMNC-style power filter (FB/diodes), and with an additional feedback loop from the output back into the input through an attenuator for optional clippy madness. Original design is 2x on one board, but this is only one rectifier, since you need to order 5 of them and the circuits in the original are isolated anyway so the part count is the same.
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