I want to use an old webcam module from a notebook which needs 3.3V. Therefore I want to solder it to a USB cable and use it at an USB port on my computer.
For now I use the 3.3V source from a raspberry, which works fine, but of course that's not very convenient. Most tutorials on the web on how to reuse an old webcam don't use a voltage regulator at all and it seems to work well for them for some reason. But I don't want to damage my computer, so I want to do it properly.
These are all the methods I found other people using to use the USB 5V for their 3.3V webcam:
| Element | Source |
|---|---|
| 2 x 1N1004 Diodes | instructables @AikonM |
| LM1117 | instructables @misterxp |
| IN4001 Diode | instructables @danjunk-DIY |
| LE33 | instructables @DiegoF42 |
| LM1117T & 2 x 10uf tantalum capacitors | thingsconnected.io |
Without the context of using a webcam I also found people using the AMS1117-3.3 see this users answer which seems to me the "safest" method so far to me.
Somewhere I also read a bout using buck converter for that.
Finally I read in this post that I probably should use a LDO switching regulator.
Now I am very confused and really don't know what to use. On the one side I definitely want to be on the safe side to not destroy my computer (and maybe the webcam itself 😉 ) and on the other side I don't want to pay more for the converter than the webcam is worth.
From what I understood simply using diodes is not safe, because both the voltage and the current are not guaranteed to be constant, since the USB specification allows a voltage between 4.3-5V. With that on my mind LM1117 or AMS1117 seem to be the better choice, but also I couldn't figure out what the difference in these two is.
Can someone explain what and also why to use it for this use case?
Sources:
- Connecting old webcam via USB
- Reusing Webcam and Monitor from old laptop
- https://www.youtube.com/watch?v=8dQfgDdJSmk
- https://www.youtube.com/watch?v=g8XbDJLKKys
- https://hackaday.io/project/110436-laptop-webcam-reuse-made-simple
- https://www.instructables.com/Reuse-old-laptop-webcam/
- https://www.instructables.com/Laptoprecycling-Webcam/
- https://www.raspberrypi.org/forums/viewtopic.php?t=140849
- https://buger.dread.cz/how-to-reuse-webcam-module-from-dead-notebook.html
- https://www.thingsconnected.io/complete-guide-reuse-laptop-webcam/
Best Answer
Simply, you need a step down voltage converter.
One common one is called LDO, those are device are dropping the voltage at a set value by dissipation. The advantage is that they are small, you only need a single component and they are cheap. However, the conversion efficiency is low as the energy is wasted.
Another are called step down buck converter. Those are usually more expensive, takes more space but are more efficient. They also produce more switching noise.
There are plenty of other types but For your purpose, the step down buck converter is the way to go. You can check on digikey for dc/DC buck converter modules. There are thousands of them. Just make sure to select one that can output the current you need.