Take a look at the trace I highlighted in RED.
Isn't that a feedback trace?
Isn't that long aster the resistor dividers, going under the second switcher's inductor?
Shouldn't the feedback divider resistors be near the feedback input pin?
is it necessary now to change it? I mean, we didn't notice that all along past reviews for some reason.
It wasn't noticed because I cannot tell from just images as I didn't layout the components myself.
It is not necessary to move, it is just common practice when driving a feedback input that any high impedance signal is kept as short as possible for minimal noise.
It is your choice as the change wont affect the circuit's function.
TBH, I lost focus from the various revisions I have done to the board, so couldn't notice these resistors to be the feedback ones. the irony is that the 2nd switcher is done better.
It is better to move them, but now I need to re-pannelize the board which is the real headache. I am gonna try though if I had time.
However, I think we are ok with this being the way it is since it is a switching regulator and even if some little noise got in the signal, it won't matter. The output of this regulator will have ripple due to being a switcher, and it is well above the post-regulator so no problem if it got a tiny extra.
I have learned a lot doing this project, thanks to you.
Here is a quick and not-so-accurate pricing for 125 boards (5 panels):
- boards assembled = 290$.
- shipping them = ~60$ or so.
- aoz1284 switchers (not in stock now) = 75$.
- 1000uf caps = 75$
- other through-hole connectors = 150$.
- mosfets = 40$ or so.
- top-side inductor = 25$.
- heatsinks = ~100$
- extra materials (thermal tape, packaging, solder, etc...) = 100$
- handling and customs = 100$
total = 1015$ -> make it 1000$.
Price for a complete ready-to-ship product = 8$. I planned to sell it for 50$ or similar, maybe 40$ at least.
I still have a lot to do like getting these through hole connectors, especially that stupid 6 pin molex one.
Plus, figuring out where to get the 3d printed connector part like this:
https://www.thingiverse.com/thing:4576696https://www.thingiverse.com/thing:2779041which is important to tightly fit the DC jack connector. I tried thinking about a small PCB instead of this but it is not good. How much does this thing cost in your experience? I could buy say 1000 piece at once, or at least 300.