Simple Oscilloscope

This is a complete replica of the oscilloscope shown in the course, with only minor component modifications to reduce costs. The original open-source project is: https://oshwhub.com/damihuang/AFE03.
A fuse has been added to prevent accidental smoke.
 
First and foremost, do not solder everything on at once; make sure the power supply is working first!
 
1. Power Supply Section:
The power supply must be connected in the correct order, otherwise it will be unusable (I won't say I ruined 10 DC-DC chips).
For the boost power supply section, mainly check the FB pin voltage. If it doesn't reach the voltage required in the manual, there are two possibilities: poor soldering or a short circuit at the back end. First, measure whether the power supply to each pin is normal. If it is normal, remove the load at the back end and measure again. If it still doesn't work... then the boost chip is basically faulty.
 
7805, LM1117, 7812, and 7912 are easy to fix. LDOs usually burn out directly and don't have insufficient power supply issues.
 
2. Operational Amplifier
(OPA) Section: If there has been a short circuit in the circuit before, consider replacing it. It is very likely that the high current will cause breakdown. The symptom of breakdown is that no matter the input, the output is always the maximum voltage (for example, a 12V OPA always outputs 10V or -10V). In addition, the input terminal of the OPA should not be too long, as it is easy to cause interference and even reduce the system bandwidth, while the output is not affected.
 
 
Additionally: Pay close attention to the shape parameters during design, otherwise only flying wires can handle it... That's why my core board is at the bottom...
 
PPS: Component selection is crucial! The 5V relay I used before couldn't be driven by 3.3V, so only one relatively good one worked and could switch gears...
 
 
That's all for now
 
. Finally, let me show you the results:
 
First, powering on:
Perhaps a closer input would be better? I'm not sure. If any experts are willing to help, please point out the problem. I would be very grateful...
 
Also, I'm going crazy from hand-soldering the FPC socket... Sitting with a soldering iron all day...
 
Summary: A high-EQ perspective: The board needs to be redesigned; it might be better.
A low-EQ perspective: Well done, don't do it again next time.
 
Video link: https://www.bilibili.com/video/BV18v411c7a9