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I have really no idea about electronics. I am trying to provide IR lighting for my night camera that I use with the raspberry Pi. The Pi is powered by a 5v usb power bank. The IR requires 12v.

I purchased these:

https://uk.banggood.com/DC-12V-48LED-IR-940nm-Night-Vision-Infrared-Illuminator-Board-For-CCTV-Home-Security-Camera-p-1280391.html?rmmds=myorder&cur_warehouse=CN

https://uk.banggood.com/48pcs-IR-LEDs-Light-Board-Infrared-Illuminator-940nm-Invisible-Light-at-Night-No-Red-Exposure-Camera-p-1281930.html?rmmds=myorder&cur_warehouse=CN

And thought getting this:

https://www.amazon.co.uk/gp/product/B071X6VYXR/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

to power from a 5V USB Power bank would work.

But it did not.

I cannot seem to find anything that will power these lights.

I also rather not do any soldering.

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    \$\begingroup\$ Your Banggood links are broken. The Amazon seller for the 5V to 12V adapter is clueless - the cable is rated for "800 milliampere hours." You rate batteries in milliampere hours - it's a measure of capacity. The adapter should be rated in milliamperes or amperes. \$\endgroup\$
    – JRE
    Aug 7, 2020 at 8:42
  • \$\begingroup\$ @JRE Hi, thanks for your comment. When i click on those links from this question they are fine. Thanks for info about 5v to 12v. \$\endgroup\$
    – Andrew Simpson
    Aug 7, 2020 at 8:43
  • \$\begingroup\$ The links work on my PC. Banggood seems to have a problem with Firefox on Android. \$\endgroup\$
    – JRE
    Aug 7, 2020 at 8:46
  • \$\begingroup\$ The LED matrix of the first link draws 1A, see Specifications in the web page: if the boost converter outputs max 800mA @ 12V, and that would be it's absolute limit, it might have died on the first connection attempt. Also, as the second lamp also has 48 LEDs, the same could apply. \$\endgroup\$
    – Jack
    Aug 7, 2020 at 8:51
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    \$\begingroup\$ @AndrewSimpson: The seller is clueless. \$\endgroup\$
    – JRE
    Aug 7, 2020 at 9:09

2 Answers 2

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Using power formula for DC circuits: Power [Watts] = Voltage [Volts] x Current [Amps]

If you are stuck with USB 2.0, then you are limited in how much current you can draw by the USB 2.0 specifications, which is 2A @ 5V, for a total of 2 * 5 = 10W.

So, you then need to increase the voltage using what's called a boost converter, which will boost the voltage up to a certain level; but unfortunately the total power you can draw still depends on the USB port, that being 10 Watts.
If we assume a 100% efficiency of the converter (ideal), when boosting from 5V to 12V and having 10W available, we will get 10 / 12 = 833 mA maximum output current.
Since the product page of the first lamp says that 1 Amp of current is required at 12V, i don't think you can ever hope to power said lamp with a USB 2.0 boost converter.

I tried to look around for a USB 3.0 boost converter with support for the Power Delivery protocol, but couldn't find any: these would support higher power, but would in turn require a USB 3.0 power back with Power Delivery protocol support.
They also might be more expensive.

Meanwhile, you could check with a multimeter the output of your USB 2.0 boost converter to see if it still works, and saved itself thanks to internal over-current protection, or if it's actually dead.

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  • \$\begingroup\$ Thanks Jack. I have read similar else where. Seems it is not possible or if it is not viable... \$\endgroup\$
    – Andrew Simpson
    Aug 7, 2020 at 9:19
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A similar product appears to have a 12V, 2A output:

SEDNA - USB Type A 5v to 12V 2A DC DC Converter with 9 x 90 Degree Adapter Jack https://www.amazon.co.uk/dp/B07952G6KT/ref=cm_sw_r_cp_apa_i_EDrlFbDWTFCZ8

2A seems to be more than enough for your LEDs. Would have commented but not enough reputation.

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  • \$\begingroup\$ Thanks. It will take a few weeks to be delivered so will see if it works then. Will let you know :) \$\endgroup\$
    – Andrew Simpson
    Aug 7, 2020 at 9:14

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