As an engineer at Spectrum Design in Minneapolis, [Carl] works with clients to get their product out to the masses. When designing a new USB-powered device, one client thought it would be a great idea to include a USB car charger with the device. The client promptly ordered a few thousand car chargers from China and everything was going swimmingly.
Everything was fine, of course, until [Carl] decided to test the Chinese car chargers with the client’s device. The USB PHY burnt out in short order, and the likely culprit was a shorted 12 volt regulator. This demanded a closer inspection, so after cracking open the charger [Carl] was amazed at what he found.
Yes, what you see on that circuit board is accurate. The manufacturer of these car chargers never even populated the switched mode regulator for this car USB charger. Amazing, considering a single 10 cent 7805 DC regulator would have almost worked for this application.
If there was ever an example of being careful when purchasing the cheapest possible product to increase profit margins, this would be it.
Ever the engineer, [Carl] sent this into the tip line as a Word document. That’s available here, along with a slide show of the pictures [Carl] snapped.