Hi, Ive been messing around with layouts and finally got one where I can connect everything. As this is my first time doing this, my question is if everything is connected. Will this layout work if DRC doesn’t say there’s any problems? I still have to add a ground plane…
From first glance:
How do you intend physically attaching this PCB?
Will the wires for the off-board connections fit in the pad holes?
Why are all the pads so small and the tracks so thin?
Are there only three connections for the pot, or are there extra case connections for physical robustness?
1 Like
I plan to solder the wires through the holes. I made sure the holes are the correct diameter to fit my wire, as well as all my components.
Should the pads be larger?
I just used Kicads standard trace. I didnt mod it. Should I have?
We call them “tracks” in KiCad.
Except for a few special circumstances, (or if there is not enough space) I like to make my tracks as wide as (or almost as wide as) the pads to which they are connecting. This does not cost you any more, and it generally reduces inductive crosstalk. It makes the tracks more mechanically robust and also lowers DCR.
Exceptions to this can be high voltage (probably > 50V) where capacitive crosstalk can become an issue, or if controlled impedance dictates a certain track width.
Okay, so if I widen the tracks will this layout work, or should I keep trying other layouts?
For that question you are asking us to reverse engineer your design.
I have no good idea as to what it supposed to do or how it is supposed to do it. Try to make our task as easy as possible so we do not need to do a lot of added homework to answer your question.
For starters:
- What is the desired output?
- What is the input?
- What is the battery voltage?
I have been engineering power (with a side of analog) since 1975 and have never used a JFET.
This is a stratoblaster, a circuit to go in my guitar. Input is a 9v battery, output should boost my signal somewhere between 14-30dB with adjustable gain.
ERC and DRC has said my circuit is fine, I just can’t run spice so I have no idea if It will work.
I am also unsure of running a signal trace on my ground plane. Im trying to make this a 2 layer.
You have a low power, audio frequency design so the fraction of an ohm decrease in track resistance is unlikely to matter but you could easily double the track width and gain mechanical adhesion and anyway your tracks don’t have to go between pads like in an IC design. Try to keep as many of the signal tracks on one layer so that you can have a ground plane on the other layer.
I note that your ground plane is a V+ plane. It would probably be better if it were a ground plane.
I have not done a lot of audio work. I am not confident enough to say “Yes that will work.”
Your potentiometer is connected as a rheostat. I think it would be best practice to add a fixed resistor in series with pin 1, based upon the desired resistance adjustment range. So a 5K fixed resistor would give you about a 20:1 range.
Why are you using through hole resistors? “I have them” is a valid reason, if that is what you want to do. But for a circuit such as this, a smaller layout is likely to pick up less noise from external sources. If you have never worked with SMT components, I would recommend trying 1206 size chip resistors. You CAN easily run a track under a 1206 chip. Many people would run two or perhaps three.
I do not know about your FET but that may be available in SOT23. I would not expect that to be so much smaller, but if you are first diving into electronics it is worth getting into the newer technology. SOT23 and 1206 packages are easy enough to work with.
Maybe OP has them. Or they bought a variety pack of resistors. Typically you have to buy SMDs in strips or reels so if you have several values that’s how many strips you have to buy. Anyway this is an undemanding circuit. They can ease into SMT later.
You make it sound like cookies from a bakery.
1 Like
Cheaper and less fattening. And shouldn’t the cookies be donots or don’tnuts?
2 Likes
I like using em
Crap. I don’t know how, or why it did that. How would I rectify it?
I use through holes cause I have them. I like em. Don’t want to mess with smd yet.
I was trying to recreate a circuit I had, it used through hole so I kept it as is.
When you create your ground plane copper fill, choose to associate it with GND net rather than V+. You can still fix it by modifying the attribute of the copper fill, then refresh.
This is odd. I set the fill zone to the GND net, yet my 9v battery plus is the one being grounded. Maybe I have them mis labeled ?
whoops. I replied in another message. I did set it as GND net. So the V+ must be my common gnd and I need to amend my pcb layout/ change names…
That is certainly OK. But understand that even to just swap out a resistor (basic rework) SMT is often easier. Think about sucking solder out of a plated through hole to replace a leaded resistor. With a hot tweezer or two soldering irons, it is significantly easier to deal with a 1206 chip.
1 Like
So you did, and it looks like your silkscreen text is wrong. Would be a disaster to connect the battery the wrong way.
1 Like
it can be hard to think in 3-dimensions when doing routing, it takes some practice.
some notes;
- unless you’re space constrained, spread things out just a little more, your fingers will appreciate not getting burned.
- delete the GND tracks you’ve made on the back layer, they’re confusing you.
- usually I just turn the fill off while doing routing, then fill (B key) then look to see if there are islands, etc.
- think about rotating R6 and R1 180 so that you don’t have to have that trace that goes all around. (or at least make that a more direct route)
- you have GND and V+ mis-labeled on the bottom input.
good luck.
1 Like