Can some one take a look at my first PCB build?
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RayCorp 1 month ago
Hello, Can someone take a look on my sheet and tell me what i did wrong? I made a PCB for this but when i apply 12v the K7803M-1000R3 is getting hot and nothing works :( Please let me know what i did wrong. <br> <br> ![image.png](//image.easyeda.com/pullimage/QnUB1D6i1EXm1TccSEx0QqgdFYV3N4krsDvuchfE.png)
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Jaan_Doh 1 month ago
Hiya Raycorp, I can't be sure as I a beginner myself... But... I think the problem is with the U2 Ams1117-3-3 circuit... That red dot I guess signifies EARTH/GROUND..., but it's not at the place where the wires cross,  so your V-Out is going straight in the V-In... And I guess that shouldn't happen... But it's probably better you wait for a professional to point out the problem as I'm a beginner myself.. <br> ![Screenshot_20211202_200721.jpg](//image.easyeda.com/pullimage/lZTrLzzCw4FeFeIaDhXDYr5ObigrJRc8PM8lgtpx.jpeg) <br> <br>
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Markus_ee 1 month ago
Hello Raycorp! The voltage regulator schematic should be drawn like this: ![+3.0V.jpg](//image.easyeda.com/pullimage/zrqrzxdRlmqQRDjGQl79TucaUZfn7rmB3awVW8Ny.jpeg) By flipping the component horizontally it makes easy to draw the signals. Also noted that that you feed 3.3V into this AMS1117-3.3 regulator. You can't get +3.3V out if you only feed it 3.3V at the input. AMS1117 series voltage regulator drops around 1.2V from the input. So by calculating 3.3 + 1.2 = 4.5V. So you need to feed 4.5V at the input as a minimum value. I also noted that your D1 is at wrong place. it needs to be between the relay coil. Anode at pin 4 and cathode on pin 1. You also need bypass capacitors at the very near atmega chip Vcc pins. Usually 1uF and 100nF ceramic is enough. Also AVcc needs to be seperated via lowpass filter from Vcc. So, you have two 3.3V regulators. I suggest that you drop one out of the schematic and use only one in this situation. I'm happy  to help with this project of you invite me. I can redraw this schematic into more readable format? Perhaps make some improvements too? Regards, Markus Virtanen HW / Electronics Designer
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Markus_ee 1 month ago
Hi! I also noted that you don't have capacitors at the input and output pins of the K7803M-1000R3. I looked from the datasheet and: \- Input pin needs 10uF electrolytic or tantalum capacitor\, with voltage rating of 25V or higher\. \- Output pin needs 22uF electrolytic or tantalum capacitor\, with voltage rating of 10V or higher\. -Markus
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RayCorp 1 month ago
Hello Markus, thank you for your anwser. I will add you to this project. When i find out how to do that. Regards, Ray
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RayCorp 1 month ago
I also see that i made a component mistake. I need 5v on the whole system with a input from 9 to 15v. Well i add you and maybe we can fix this. Again thank you for your help.
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Markus_ee 1 month ago
No problem, I'll wait when you get me added to your project. There is three options to invite a member. 1) Add member by its username 2) Invitation link/QR code Send the link to PM chat 3) Invitation via email address. But I guess the best option is nr. 2
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