Need help with a circuit

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Thread Starter

S_Madrone

Joined Oct 1, 2023
10
Hello,

I'm wanting to build a circuit on a small PCB. I've gotten some help here from a couple of members--thank you gentlemen--yet I'm stumped on getting this thing to fly.

All I have is a photo of the completed circuit on the PCB, a wiring diagram and a parts list. The photo shows capacitors, an LED and other items not seen in wiring diagram or parts list. One tidbit of help came from MaxHeadRoom where he pointed out a missing Vref circuit on the Arduino Nano in the wiring diagram and gave me this:
1696479110928.png
With this information:
You set the pot to the voltage on pin15 based on the volt drop across the sense resistors based when max current for the motor is present..
R51 R52 would be ~0.5ohms , not wire wound type.


So here is the photo, wiring diagram and parts list. I feel I need the help of an EE (or anyone really) who can interpret from the photo, understand the design in the wiring diagram and help me solve all of what's missing in the wiring diagram to draw a complete wiring diagram showing what is connected where.

Photo:
1696478732503.png

Wiring Diagram:
1696477894380.png

Parts List:
  1. Arduino NANO
  2. A4988 STEPPER DRIVER
  3. ROTARY ENCODER
  4. 16X2 I2C LCD DISPLAY
  5. NEMA 17 STEPPER MOTOR
  6. MOTOR
  7. L293D IC
 

Thread Starter

S_Madrone

Joined Oct 1, 2023
10
My question is to " help me solve all of what's missing in the wiring diagram"
My hope is for someone to look at the wiring diagram, understand better than I what the components are there for, and identify what is missing with a clue from what can be seen in the photo. MaxHeadRoom did this partially when he pointed out a needed Vref circuit missing in the wiring diagram and provided a schematic and instructions (which I pointed out in my post).
 

Thread Starter

S_Madrone

Joined Oct 1, 2023
10
Thank you MrChips. Would you help me understand that if the wiring diagram is complete then why are there capacitors, an LED and other components on the PCB not shown in the wiring diagram? I don't think the creator of the video just added them to look pretty or use up spare parts.
In my limited experience, when I see a circuit wiring diagram, it has always shown where needed resistors, capacitors, pots, etc. are in among chips and/or other components.
Again, member MaxHeadRoom pointed out in another post he sees a missing Vref in the wiring diagram. He also shared I would need a stepper translator for constant current control, as well as bridge drive, e.g. IC, L297/L298 combo, and provided schematics for both. Kudos to Max!
 

MrChips

Joined Oct 2, 2009
30,488
I see what could be two 3-terminal voltage regulators, necessary capacitors, LED to indicate power, and some male pin headers for jumper selection.
 
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