I’d like to firstly thank this community for helping me grow my knowledge in electronics and PCB design.
I came up with my first very own layout of a PCB project.
Do anyone has comments to make about it? I did another version with a signal plane but I don’t know if that’s acceptable and correct in addition to the ground plane.
I know the battery footprint is being cut out in this layout, but it’s because when I go etch the PCB I’ll just use a wire connector to power it.
Based on previous advice, I tried to max out the ground plane area by reducing as much as possible the amount of traces on the front copper layer.
It’s a an ECG project. I was told that in order to avoid EMI, there should be a guard ring protection, how and where could I implement it into my design?
The vias are there because I’m using a fenolite copper plate to manufacture the PCB therefore I need to put a cut resistor terminal through the via hole to connect both sides of the PCB.
Comments from my side:
If this is a first attempt, it’s very good. Your track widths are fine for home PCB etching. Concerning routing, it’s hard to say, component placement plays a big role here, and you might have limitations on that point. If you are free there, the “Rats Nest” functionality is the greatest invention in PCB layout ever.
But like RaptorUK, I also question your use of vias. On a THT layout, a via can usually be relocated to a real component pin.
Here’s an example of one of my older THT designs (not done in KiCAD). Semi-complicated, but without a single via anywhere.
Why resistor terminal that is not cut can’t do that job?
I suppose that high impedance signal is connected somewhere and that point should be surrounded with track connected to the other point of circuit with the same potential but low impedance (or other (may be GND) with the task to isolate that point from external influence (nA can counts)). To say more someone needs to understand circuit so schematic (and time) is needed. Seeing how many ICs you have time to analyse circuit can be a critical factor.
Hi ML9104, thanks for the reply.
I decided to use vias as the local electronics shop owner told me it would be easier to solder it instead of soldering on the top layer pins of the board and it would be easier to remove components.
I see Piotr. Thanks for the reply.
By analyzing the circuit do you mean the distance between tracks and it’s influence in EMI?
I’m afraid the circuit won’t generate clean signal if tracks are too close or different of how they should be.
There’s a size issue also. I want to start manufacturing PCBs with a laser engraving machine which can only engrave an area of up to 8cm x 8 cm.
Therefore, it might be hard to use the TL071 as the main IC as it takes to much space. I’ll probably need to change to a TL072 or TL074.
@giovannelucas are you aware that there is at least one unrouted connention?
You mentioned that your local shop gave you hints about soldering, so I assume you are not most experianced. I agree, that THT DIL sockets are tricky to solder on component side.
And I can fully understand that making a pcb at home is a wunderfull experience. But to be honest, nowadays it has become obsolete, as sad as it is. Homebrewing as so many downsides. IMHO your project is ambicious enough from the circut pov, a pcb with no vias nor soldermask nor silkscreen adds a lot of traps. I suggest to have the pcb from a fab house the first (couple of) projects. Then go the next step and make your own, to enjoy the fun of it.
Yeah I remember the fun of it . . . spray on photoresist, Caustic Soda to remove photo resist, Ferric Chloride to etch the copper, and some really nasty stuff to do some tin “plating” . . . I really don’t miss all that “fun”.
I also don’t miss all the kit I bought to try and get an acceptable result or the storage of the chemicals that I probably wouldn’t be using for the next few weeks/months.
I’d much rather spend my time on the schematic and PCB layout.
@RaptorUK, that are the words I tried to hide in the abravation „fun“. But I did not intend to disencourage anyone. And after all, all those experiences, are the successfull or not, gave us the expertise we have got now. My first electronic project was 42y ago and ended up in a smelly cluster of burned entities. I really learned a lot, at the age of 12.
No.
I was answering after citing your question about guard ring. The problem is that we don’t know which net is to be protected with guard ring and to what net this guard ring is to be connected. I understand guard ring as a circle made of tracks (connected to selected net) around other sensitive net.
If someone told you about guard ring than probably he was knowing which net need to be protected and what other net potential can be used for it. Not always GND is used for it. For example if you have transistor follower the emiter potential can be used to protect base net if there is high impedance.
8x8 cm is huge area. Do not be afraid to use SMD elements and you will need 1/4 of area you need with THT elements. SMD elements are even simpler to solder as you need not to continuously reverse PCB while soldering it.
I was using (1970+) pen refill with removed ball for painting tracks directly on the PCB.
My first was detector radio receiver I made in 1968 and was very surprised that at all positions of variable capacitor (50…500pF) I was receiving the same station (227kHz (Polad Warsaw I) - probably the highest radio mast those time in Europe - something about 600m height).
If you want more advice about how to realize a schematic and a layout in KiCad, and what kind of layout would be good, you could attach the whole project here. It’s difficult to interpret the layout in the small resolution screenshot especially without the schematic.
I’m not sure how to respond here.
This PCB clearly has some unusual attributes apparently designed in for easy home etching. And such things are quite … “personal”. It does make the mention of guard rings also a bit out of tune. Guard rings need some knowledge to apply properly, so do some research on that.
For the track layout, there clearly was an attempt to make a decent ground plane. It is however still quite easy to make the GND plane better. by reducing the length of the red tracks through the GND plane, and quite a lot can even be moved to the blue top layer altogether.
I figured it actually cheaper than I thought to get boards manufactured at JLCPCB. To get it sent to Brazil can be expensive but I found a cheaper shipping option which makes this process viable and way cheaper than brazilian PCB factories. As requested above, I’m sending the zip file of the project. I’m not sure how the ground plane should be but I followed a Phill’s Lab tutorial logic sending it to back copper plane with vias.
Also changing over to SMD, allowed me to reduce the size of the board as well. Thanks for the tip.
When routing PCBs with multiple signal layers, try to orient the traces in one direction on one layer, and the orthogonal direction on the adjacent layer. This makes it much easier to add traces without having to jump through hoops to route them (and also makes it easier to modify the layout at a later stage).
