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PCB designers

MPU

MPU

Sep 21, 2004
3,703
10,692
56
Valkeala Finland
#1
Well, here I am again, asking for help. I've watched a dozen videos about making a PCB out of schematic and found out that I'm never going to succeed in making one. So, is there anybody out here that could help me and make a PCB design out of this HAZ preamp schematic? I'm more than happy to pay something for help. There are some errors on values of the capacitors but they are sorted out already. That stripboard layout misses one jumper as well.

9F1BDC1C-76DD-4427-866D-D337638945ED.png
 
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#2
I will take a shot at putting it together. I might make some myself, I would like to try a different preamp design to have a comparison to what I'm using now. I really like the design I'm using now but it's a little more complicated than it needs to be and uses some obscure parts.

Do you need a certain output format for the finished design? I use EasyEDA for design and export gerbers to get pcbs made at OSH Park. OSH Park is really, really cheap and pretty fast. I usually only pay $5 or $6, shipped, for three boards when it comes to something preamp-sized.

Any size restrictions on the PCB itself? Does it need to fit in a certain sized spot?

Do you want through hole or SMT parts? I would normally do something like this SMT with 1206 sized parts for the passives. And through hole for the electrolytic caps. And probably SOIC 8 for the op amp, or plain old through hole pdip if SOIC 8 wasn't available.

Do you want that 330p cap on the VR4 pot on the pcb instead of on the pot? I would assume yes, it seems like it's only on the pot out of convenience because of the stripboard layout.

Also can you point out the incorrect cap values? Might as well put the real ones in the design.
 
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#3
I've been known to play in this arena. I've even been known to get paid for playing in this arena, if a long time back. What sort of board are you thinking (1-side, 2-side, 4 layer, SMD, through hole, hybrid?)

Values of capacitors are a part-stuffing issue more than a PCB layout issue, so long as the space available fits the capacitors you want to use, of course.
 
#5
dwizum said:
Here's a shot at the schematic in EasyEDA. I'll start the layout of the PCB. I'm assuming 1206 smt parts, soic-8 for the IC, etc.

View attachment 4191628
Click to expand...

Thanks!
Here's the correction for cap values. I like to use thru hole components and dip8 IC socket. Sizewise as small as possible, 330 cap on the board as well. If possible single layer PCB and printable so that I can etch the boards at home. If that's not possible, I have to order from OSH Park.
05A272CB-DEFF-4207-9181-3CD5F6A4A1B7.jpeg
 
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#6
Speaking as "old enough that SMT wasn't a thing when I started" I will advise that (non-absurdly small) SMT parts are really not so bad to work with (& can be done with a soldering iron and tweezers rather than a reflow oven) and offer upsides (smaller boards, less need for holes, lower inductances on bypass capacitors) - besides which some parts are hard to even get in DIP these days.

You want what you want, but it's not all bad (I went into my first SMT project full of doubts, and came out feeling much better about what I and my long conical point ancient Weller could do when needed.) Likewise, the DIY-cachet of making it at home pairs up with proper disposal of chemistry .vs. relatively low cost, high quality outsourced board options such as OSH Park, and the things you can do on a multilayer board that are not an option on one layer.
 
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#8
I had thought those were really strange values. It looks like someone interpreted the marking on the cap (two digit value, third digit order of magnitude) as if it was just a three digit value in p.

I'm almost done with the SMT layout. It looks like it'll be about one inch by two inches. EasyEDA will spit out a BOM that you can upload to most electronics suppliers and then you just have to filter through the matches. The isn't anything exotic on this design so parts should be really easy to find. I will probably shop at Arrow, I don't know if they deliver to the EU but I would be surprised if they didn't! I will share my cart at Arrow if you want to just order there too.

I will take a shot at a through hole layout once I have this version done (unless someone else wants to), but just based on looking at the stripboard layout I doubt it'll be one sided.
 
#9
It will take me a few weeks to get to the free time needed, I suspect, as I haven't played with designing much recently.

One sided can pretty much always be achieved (for audio frequency stuff, anyway) if you are willing to use jumpers when needed (I spent a while constrained to making one-sided boards, which I could do on-site at work, but trying to get approval for outsourcing in those dark ages was difficult-to-impossible. Beat the heck out of the perf-board rats-nests I was replacing.)
 
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#12
Here is the SMT version on OSHPark, ready to order. Let me know if anyone wants it in any other format.

OSH Park ~

It ended up a little bigger than I wanted because I wanted to make sure there was enough room around the SMT compoents such that they'd be easy to solder. $11ish for three. It could probably be about half this size if we wanted to have components on the bottom layer (put all the SMT passives on the bottom) and pack things closer together.

I'll take a shot at a BOM on Arrow and then try a through hole layout.
 
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#13
This might be the easiest way to share the BOM since I can't figure out how to share carts at Arrow (I just started using them after 20 years of Mouser). This is part number, quantity, reference number. You should be able to paste this into any supplier's BOM tool.

CL31B473KBCNNND 1 C1
CL31C101JGFNNNE 3 C2, C4, C5
SMK316B7222MFHT 1 C3
SMK316B7223KLHT 2 C6, C8
CC1206KRX7R9BB3311 1 C7
ESK107M016AC3AA 1 C9
USA1H4R7MDD 2 C10, C11
SMK316B7682KF-T 1 C12
1N4004E3/54 1 D1
ERJ-P08J123V 2 R1, R10
MCA12060C1004FP500 1 R3
RK73B2BTTDD513J 1 R2
NRC12J514TRF 1 R4
CRCW1206100KFKTA 3 R5, R6, R11
CRCW120620K0FKTA 3 R7, R8, R9
CR1206-FX-1201ELF 1 R12
CR1206-JW-512ELF 1 R13
TL062CD 1 U1

Total is about $4.50 at Arrow in the US. You will also need the three pots but they should be easy to find and may vary depending on your installation.

I'm going to order the PCB at OSHPark and this BOM at Arrow, I'll report back in a few weeks once the PCBs get here. In the meantime I'll take a shot at the through hole layout when I get some more spare time.
 
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#19
MPU said:
I have made a couple of these preamp with stripboard and I can't hear any noise. Might be there but not at audible amounts.
Click to expand...
Yes, you're right, resistor noise (don't recall if it's thermal or flicker, it's been too long...) would have be a problem if the virtual ground reference for an inverting stage had such a high impedance connection, such as U1.1 pin 4, but R4 is the vref for the non-inverting stage. My bad.
 

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