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I am a newbie starting a project on an Arduino. One part of this project is to design a complete AC-DC converter to feed:

Input: 230 VAC

Outputs:

  1. the Arduino with 5 V,
  2. one set of Arduino 5 modules with 5 V,
  3. a pair of 230 VAC relays controlled by the Arduino (5 V),
  4. a 12 VDC fan.

I try to use fiable components as to eventually go throught EMI tests.

Mounting holes are connected the "protective earth" of the electrical wall outlet via capacitors. The 12 V output is protected by a TVS.

Please do not hesitate to comment on the schematic, I really want to progress on this deliverable. enter image description here

alvaro562003
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  • change the `GND1` label to `AC/N`, or similar .... add earth ground symbol to the mounting holes – jsotola Jan 21 '23 at 19:42
  • @jsotola, i am using kicad. When i add earth/earth clean/earth protective symbol, the ERC generates errors. – alvaro562003 Jan 21 '23 at 21:26
  • @jsotola, there is no symbol ac/n on kicad....or i did not find it. – alvaro562003 Jan 21 '23 at 21:29
  • The 2 independant grounds are in 2 blue parts. The first one, 230VAC, is connected to the AC/N via the J4 Screw terminal coming from the outlet plug. – alvaro562003 Jan 22 '23 at 10:19
  • There is no connection dot at pin 2 of the VTX device. So avoid confusion, separate two line that cross and are connected into two closely-spaced T junctions, still with connection dots. Also, the components at the AC side of the supply are crammed together. Spread them out for clarity. – AnalogKid Jan 23 '23 at 18:10
  • Which kind of outlet plug you have? Can it be plugged to socket in any orientation or only in single orientation? Or will this product be installed by a professional electrician? In other words, do you trust that Live and Neutral are never ever swapped, 100% of the time? Are the capacitors rated for appropriate mains safety class? – Justme Jan 23 '23 at 18:14
  • @Justme thanks. for the socket, it is the standard wall outlet. 2 orientations could be possible as it is AC. – alvaro562003 Jan 23 '23 at 20:47
  • @justme thanks again. The value of C1 and C2 are computed based on ripples. I will clarify the value of C3 and C4 soon. – alvaro562003 Jan 23 '23 at 20:57
  • @justme : To suppress the high frequency common mode is is necessary to put capacitors between the input and output side of the power supply with a capacitance substantially higher than the capacitance in the flyback transformer. This effectively shorts out the high frequency and prevents it escaping from the device. Source: What does the Y capacitor in a SMPS do?. Here https://electronics.stackexchange.com/questions/503301/why-a-capacitor-is-connected-between-two-ground-terminals-and-what-difference-do – alvaro562003 Jan 23 '23 at 20:59
  • @Justme value of C3 coming from the VTX datasheet – alvaro562003 Jan 23 '23 at 21:07
  • @AnalogKid thanks. The pin 2 of VTX, is connected to the ground that terminates the varistor and capacitor. – alvaro562003 Jan 23 '23 at 21:10
  • I know that. My point is that the schematic does not show that. – AnalogKid Jan 23 '23 at 21:13
  • @alvaro562003 The standard wall outlet does not exist. You would at least have to specify a country, and each country may have multiple standards. Grounded plug or ungrounded? I know why the caps are there. My point was, what if someone swaps L and N, or leaves PE unconnected, will your device burn up or electrocute someone? There is no symmetry, which might be fine if you expect L and N to be always 100% correctly connected as per your assumptions. Also the caps must have correct X and Y class rating or that power supply is dangerous. It may be easier to buy a supply than to build a safe one. – Justme Jan 23 '23 at 21:26
  • @Justme right, grounded outlet as in France. the connector would be https://fr.farnell.com/multicomp/sl-19-sl-6-2/lead-iec-c19-to-euro-plug-2m/dp/1717219 – alvaro562003 Jan 23 '23 at 21:36
  • @Justme which supply could you recommend ? – alvaro562003 Jan 23 '23 at 21:37
  • @ AnalogKid, yes it's a bit tight. I will clarify it soon. Thank you. – alvaro562003 Jan 23 '23 at 21:39
  • @alvaro562003 Asking and suggesting specific products or where to buy them is off-topic. Plus, I would not know what to suggest. I also don't know what you need, such as do you really need dual isolated outputs. And you still have mains relay wiring which does not remove the problem of having to work with mains voltage wiring. – Justme Jan 23 '23 at 21:41
  • @Justme I googled "dual output voltage" and find this https://fr.rs-online.com/web/p/alimentations-a-decoupage/6447067 – alvaro562003 Jan 23 '23 at 21:44
  • @alvaro562003 And France has two mains socket types. Grounded and ungrounded. You (or someone else who does not know or care about plug types) can plug your grounded Type F plug into ungrounded Type C socket in any orientation, and in 50% of cases your device will be dangerous, as you only have a capacitor from Live to ungrounded metal case. Do you really want to be in a hurry with your product deliverable? It would not pass safety tests, that are mandatory for getting a certificate for selling that electrical equipment legally. – Justme Jan 23 '23 at 21:51
  • @Justme I must admit you are right. – alvaro562003 Jan 24 '23 at 08:08

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It is almost ok except that the output current from IRM-02-12 is very low (167mA) so you are not going to get the rated output you show for J1 and J2 even though the K7805-500R3 is capable of. Also, I couldn't check D1 (5M6T24A?). IRM-02-12 datasheet K7805-500R3

Rodo
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