DipTrace

[simon]

I've played with the ground copper pour and as long as I leave the original net alone which I associated the copper pour with I get no errors. If I then delete the GND net I get the errors. I guess this makes sense.

My reason for deleting the GND net was to tidy up the spokes - below you can see the additional 45 degree traces. I could simply move the net so it only attaches to pads at 0, 90, 180, 270 degrees, but there must be a "proper" way of doing it.

Ground plane net spokes.PNG (8.01 KiB) Viewed 2198 times

[simon]

Here's v2. I've moved the 10uF bypass caps next to the power input header, widened the traces to 1mm, and added the bypass caps to the feedback resistors. And don't get any errors now (with the GND net caveat above).

Next I might try adding the power supply on the same board, unless that's a bad idea?

Op Amp Gain Stage v2.PNG (58.85 KiB) Viewed 2198 times

[Nick]

You could add a ground trace between the two input traces to reduce coupling between channels.

[simon]

On the top side, down the middle of the op amp?

[Nick]

On the top side, down the middle of the op amp?

I don't know which is top, but on the same side as the two in traces from the terminals, between them just add a trace and connect it with via to the ground plain on the other face.

[simon]

Something like this? I've attached it to the GND for the power supply, sort of the star earth I suppose, rather than a via.

Op Amp Gain Stage v3.PNG (60.9 KiB) Viewed 2187 times

[Nick]

Yes, that's what I meant.

[simon]

But yep, arn't PCB's easy.

Don't know why but ever since I read this, this has been going through my mind . (Nuts! Looks like you have to click on the link. Int milk brilliant!)

[simon]

I installed library loader but Chrome blocked a synchronising file it wanted to put in the Downloads folder as part of the setup. It wasn't clear why but I got the impression it was blocking it because it suspected it contained malware.

I did download a suitable Ecad for a Wakefield TO220 heatsink but DipTrace gave a wrong format error when I tried to import it. And when I looked at the list of 3D models in DipTrace it wasn't listed even though it was in the folder.

It's a little frustrating, I can't get much further without the heatsink model but don't feel inclined to investigate the missing syncronising file.

[simon]

Talked to a friend tonight who's been using the free version of Eagle. It's limited to a board size of 80cm^2 but it sounds like it has a much better library, he even requested a part that didn't exist and 2 days later they'd created it for him. So I might try Eagle.

[Nick]

Yep, I use Eagle. Its easy to create new parts in the library editor as well.

[ed]

never had a problem with designspark...free from RS

[simon]

Look what just arrived

20221122_115925.jpg (131.78 KiB) Viewed 1793 times

It's silly really. I uploaded the gerbers 8 days ago. 5 boards cost £1.69, shipping charge was £4.62 (for cheapish shipping), customs duties and taxes were £1.27. A total of £7.58 and 8 days. How we'll ever compete with China is difficult to imagine.

[Nick]

Yep, and it starts to become hard to justify not using a PCB for even the simplistic prototype.

[simon]

Indeed it does