breadboardcurrentpower supply
Easy question. I'm a noob… I bought a MB102 breadboard power supply unit. But, it doesn't come with a manual. I need to get a 9V adapter for it. So, I'm not sure what I need.
Does the 9V adapter's current matter or will any 9V wall wart work? What is the max. input mA for the MB102?
You're in luck: I just posted a detailed teardown and schematic of the iPhone charger. Internally it's a complex flyback quasi-resonant switching power supply controlled by a L6565.
Building your own switching power supply is probably more complexity and danger than you want to include in a project. I'd recommend going with the wall wart - there's a reason most products use one. If you really want a built-in power supply, I'd recommend getting a pre-built OEM one rather than building your own. And if you really want to build your own, I'd recommend a simple linear power supply instead of a switcher.
The probable problem is that the USB VCC and BPSS (Breadboard Power Supply Stick) 5V output are hard connected together and the regulator on the BPSS acts as a load to the USB 5V supply. See "Vcc back-feed" diagram below.
Breaking the 5V feed between the two power supplies MAY be all that is required.
This may cause "issues if the two nominal 5V supplies are substantially different in voltage but will probably work OK.
Care needs to be taken in choosing which items work on which supply.
An active switching arrangement that connected the two supplies only when both were powered may be useful but should not be necessary.
Best Answer
Here is the schematic:
It needs to be rated for the total output current (current on the 5V line plus current on the 3.3V line) you want plus a few tens of mA for the LEDs and regulators. Other than that, any regulated 9V adapter with the right polarity will work fine. Unregulated ones will also work provided the unloaded output voltage isn't too high.