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I've finished the initial revision of my module. I'm just wondering if anyone has any feedback for the schematic layout. Is there anything that I could have done better?

This small module will be used with a water tank to:

  • control a relay to switch 12 V between NO and NC that will open/close a valve
  • measure water temperature using a DS18B20 sensor
  • calculate water level through a 0-200 Ω resistive sensor via a voltage divider

Can you see anything wrong with the components I have chosen or the layout?

I'm not sure about using a N-MOSFET to drive the relay, or if I should just use a BJT.

I appreciate any feedback. I'm no EE, however I'm trying to learn in Eagle.

ESP32-C3 based water tank module

SamGibson
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robbrown92
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    I don't see anything obviously wrong with the schematic but it is made difficult to check because it's broken into so many disconnected blocks and tracing the circuit requires searching the page for any occurrences of the net label. Does anyone have any idea why this form of schematic has become so popular? See these scans of [beautifully crafted schematics](http://retro.hansotten.nl/wp-content/uploads/2019/12/Junior-Schematic.jpg) and PCB layouts from Elektor magazine from the 1980s! – Transistor Sep 17 '22 at 21:45
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    Is that USB connector a host? Or a device? Because you likely damage your PC or regulator if PC is turned off while the 5V regulator keeps feeding the PC. Also regulator may get damaged if it has no input and PC powers the 5V side. In which case your schematics also exceed the maximum allowed capacitance of 10uF by multiple times. The schematics don't convey enough information itself to know what the devive is supposed to do and within what parameters. Also schematic review questions are difficult, how do you decide which is a correct answer, if all answers say different things? – Justme Sep 17 '22 at 22:08
  • [Olin Lathrop](https://electronics.stackexchange.com/questions/28251/rules-and-guidelines-for-drawing-good-schematics) has a good discussion. – RussellH Sep 17 '22 at 22:46
  • @justme the usb is solely used for programming , would it be worth putting a diode on the output of the 5v regulator to prevent reverse current when usb is connected ? When programming it will not be connected to 12v in – robbrown92 Sep 18 '22 at 11:04
  • Whats the purpose of R1? And the value of R3? 470 Ω or 4.7k Ω? Do you have a datasheet for the water level sensor? – RemyHx Sep 25 '22 at 06:55

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As a diagram, the main thing wrong with it is there's no title block, there are no versions, dates or revision numbers! And no border grids -- so necessary for talking on the phone or shortening those pesky videocalls.

It looks a little cramped (especially the relay section). I might suggest USB on the left, then CPU, inputs and outputs on the right. Label the connectors. Use a paper size a bit larger. But don't be discouraged: it takes practice and time to make a good diagram.

There's a nice blog about this kind of thing at https://bimblog.house/2016/11/21/drawing-to-conclusions/

  • ISO 5457 for image borders
  • ISO 7200 for title block

The A3 template I use has red keepout zones, including where the holes will be when A3 is printed on A4. enter image description here

jonathanjo
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  • This is a good comment. But not an answer. – RemyHx Sep 25 '22 at 04:34
  • @RemyHx I suppose it depends how you look at it. Questioner asked "any feedback for the schematic layout. Is there anything that I could have done better?" and I gave concrete answers for things which could be done better. – jonathanjo Sep 25 '22 at 11:48