I have taken a 3.3V webcam out of an old laptop and have tried to get it to run on USB with a different computer.

My first attempt of cutting off the end of a USB phone charging cable and soldering the wires to the camera was successful, but it quickly overheated since USB was giving it 5V instead of 3.3V.

To fix the overheating problem, I bought this 3A 5V-23V to 3.3V 6V 9V 12V 340KHz Mini DC-DC Step-down Converter Voltage Regulator Power Supply Module:

3A 5V-23V to 3.3V 6V 9V 12V 340KHz Mini DC-DC Step-down Converter Voltage Regulator Power Supply Module

I also wanted to try to replace the hardwired USB cable with a female micro-USB connector (so that I could use different length cables depending on what I use it for), so I also bought this Micro USB To Dip Female Socket B Type Microphone 5P Patch to Dip 2.54mm Pin with Soldering Adapter Board:

Micro USB To Dip Female Socket B Type Microphone 5P Patch To Dip 2.54mm Pin With Soldering Adapter Board

I used a voltmeter and a screwdriver to set the step-down board to about 3.39V and when I resoldered the camera to these pcbs (using a USB to micro-USB charging cable to connect to the female micro-USB pcb connector to my computer), my computer no longer recognized the camera USB connection at all. What am I doing wrong?

My wiring looks like this: Picture of webcam data cables wired to USB female data cables and power cables wired to stepdown pcb

Webcam wire color pinoutAccording to the webcam board, black is 3.3V, orange is ground, brown is D- and red is D+.

I connected the webcam's brown to the female micro–USB D- and the red to the D+ as shown. female micro USB pcb with red wire on D+, brown wire on D-, pinned orange wire on VBUS and pinned purple wire on GND My own orange wire (separate from the webcam's orange wire) coming from VBUS and the purple wire on GND then go to the step-down board as +IN and -IN respectively. step down pcb with orange wire to +IN, purple wire to -IN, and webcam black and orange wire to +OUT and -OUT respectively The +OUT and -OUT (which I have measured and should be at about 3.3V) then go into the webcam's black and orange wires respectively.

To test what was not working, I tried to bypass the female micro-USB connector pcb, but keep the step-down pcb in by using the original hardwired USB cable I had used, and the camera was recognized and seemed to be running on 3.3V instead of 5V.

I'm assuming from this that my problem comes from a misunderstanding of either micro-USB female connectors in general (like what to do with the ID (looks like an IO on the board I bought) pin (I have tried leaving it unconnected and also connecting it to ground which i figured from here)) or a misunderstanding of the specific female micro-USB connector board I bought.

I've already found this post also, but I am having trouble understanding if the information provided applies to my case or not.

  • 4
    \$\begingroup\$ What is the question here? We can't see how you wired the things together for errors, but since it still works there is no permanent damage from using the 3.3V device with 5V, but it could have destroyed your PC since USB data wires are 3.3V only. Basically it should just work but maybe there was incorrect wiring or bad connection. \$\endgroup\$
    – Justme
    Jan 8, 2022 at 16:38
  • \$\begingroup\$ I edited my question with to include the proper info \$\endgroup\$
    – Jack-Penn
    Jan 8, 2022 at 18:23
  • \$\begingroup\$ Tip: 'V' for 'volt'. \$\endgroup\$
    – Transistor
    Jan 8, 2022 at 18:26
  • \$\begingroup\$ Are you sure the D+ and D- are the correct way, and the soldering makes a proper connection? Have you used a multimeter to check the connections? Also, if you are not aware, USB data pins are a differential transmission line, and they are usually twisted together to make a twisted pair transmission line. It looks like the wires were twisted together but you have untwisted them for a significant length so it may fail to work because wires are just dangling alone in the air. \$\endgroup\$
    – Justme
    Jan 8, 2022 at 18:40
  • \$\begingroup\$ For USB-2 the maximum unshielded, untwisted length is 7.5 cm (but 2 to 3 cm is more reliable). The length of the D+ and D- lines shouldn't differ by more than 2.5 mm. \$\endgroup\$ Jan 8, 2022 at 23:39


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