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Can you please verify my schematic
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leonllrcraft 2 weeks ago
![my schematic](//image.easyeda.com/pullimage/sMMjW1hzC4vaTdk17FAkHnfg5COQePQInw7f3yQa.png)Hey, I made a schematic for some sort of console/devkit, I'm sorry if you're supposed to ask another way, can you review my schematic to verify if I made any mistakes, tanks you in advance? <br> <br>
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andyfierman 2 weeks ago
Please 1. change the Category of your topic to **Schematic; ** 2. choose which of EasyEDA Std or Pro you are using;  3. Add a link to a public project so that people can see your schematic and not just an image of it.
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leonllrcraft 2 weeks ago
@andyfierman thanks
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andyfierman 2 weeks ago
@leonllrcraft, Please also read: [https://easyeda.com/forum/topic/How-to-ask-for-help-and-get-an-answer-71b17a40d15442349eaecbfae083e46a](https://easyeda.com/forum/topic/How-to-ask-for-help-and-get-an-answer-71b17a40d15442349eaecbfae083e46a)
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andyfierman 2 weeks ago
@leonllrcraft, Just from a look through your image of your schematic, it looks like you have some work to do on it. Here are my observations and comments. **==========================** **Requires immediate action!** **==========================** B1, B2: **NEVER** connect Lithium Manganese Dioxide batteries in parallel. Although B1 and B2 are battery holders, they allow two batteries to be fitted and shorted together. If one battery is at a higher voltage than the other then the higher voltage battery will discharge through the lower voltage battery. Either or both batteries may then overheat and possibly ignite or even explode. If you need more battery capacity, use a larger capacity battery or fit a separate diode in series with each battery and only connect the diode cathodes together. * Question: did you intend to connect these battery holders in series? <br> <br> **General**: * Read all component datasheets and apps note thoroughly and carefully. * The schematic is untidy and hard to read with wires poorly placed and crossing over device symbols. * H5 and R2 in the lower left corner (F1) appear to be an unconnected mess. * Except for C1 there are no supply decoupling capacitors. * Recommend you read and run the simulations in: [https://easyeda.com/forum/topic/UPDATED-Power-supply-decoupling-and-why-it-matters-30a39d0a77f34d5d8dc77e37c035b3d3](https://easyeda.com/forum/topic/UPDATED-Power-supply-decoupling-and-why-it-matters-30a39d0a77f34d5d8dc77e37c035b3d3) <br> <br> **BUZZER1**: * It will not work. This part is rated for a 5V supply with a minimum quoted as 4V. It is also rated as drawing u to 30mA: [https://datasheet\.lcsc\.com/lcsc/1912111437\_CY\-Changzhou\-Chaoyin\-Elec\-C194267\_C194267\.pdf](https://datasheet.lcsc.com/lcsc/1912111437_CY-Changzhou-Chaoyin-Elec-C194267_C194267.pdf) It is driven from an ATTINY with some unreadable part number which is itself supplied via a silicon diode with a forward drop of at least 0.5V from a 3V battery. <br> **C1**: * This is the only supply decoupling capacitance in the whole schematic. It is too small to be of any use as a bulk decoupling capacitance for the whole board and, if intended as a local decoupling capacitance, it is not clear which, if any, device it is associated with. <br> <br> **U1**: * No local supply decoupling; <br> <br> **U2**: * No local supply decoupling; * Pin 13 is floating. In your application this pin should be tied to ground. [https://assets.nexperia.com/documents/data-sheet/74HC_HCT165.pdf](https://assets.nexperia.com/documents/data-sheet/74HC_HCT165.pdf) * Depending on clock frequency you may get contact bounce in the pushbutton switches passed through to the BIN_OUT net on pin9. <br> <br> **U3**: * No input side or output side decoupling. See the original manufacturer's datasheet for the LM1117: [https://www.ti.com/lit/ds/symlink/lm1117.pdf](https://www.ti.com/lit/ds/symlink/lm1117.pdf) The datasheet for the part from LCSC is not as well written: [https://datasheet\.lcsc\.com/lcsc/1811142212\_Advanced\-Monolithic\-Systems\-AMS1117\-3\-3\_C6186\.pdf](https://datasheet.lcsc.com/lcsc/1811142212_Advanced-Monolithic-Systems-AMS1117-3-3_C6186.pdf)<br> <br> <br> **LED1, LED2**: * These will not work. These are supplied via a silicon diode with a forward drop of at least 0.5V from a 3V battery. The recommended minimum operating voltage for the WS2812 device is 4.5V. * They also have no local supply decoupling as shown in the datasheet. [https://cdn-shop.adafruit.com/datasheets/WS2812.pdf](https://cdn-shop.adafruit.com/datasheets/WS2812.pdf)<br> <br> <br> **LED3**: * It may be very dim. This is supplied via a silicon diode with a forward drop of at least 0.5V from a 3V battery. The listed forward drop of the XL-2012UCG LED is a minimum of 2.7V @ 5mA: [https://datasheet\.lcsc\.com/lcsc/2101201032\_XINGLIGHT\-XL\-2012UGC\_C965815\.pdf](https://datasheet.lcsc.com/lcsc/2101201032_XINGLIGHT-XL-2012UGC_C965815.pdf) Choose a LED with a lower forward drop such as a red LED with a forward drop of around 1.8V.
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