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Adapter voltage question

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New Member
I need to provide 8V - 12 V to my microcontroller and i dont have a power supply. I am using an old adapter with 12 VDC rating and when i plug it in and check it with my voltmeter it says 17V. Could i use a simple voltage divider to get 10V or is that a risky thing to do? Or should i just invest in adapter?


New Member
adapter voltage

:D hi,

just add a 12v or 9v regulator to the output of your adpater if you like to tinker around with electronics. :D


Those 12V DC wall adapters are highly unregulated, and, as you have found out, their unloaded voltage is around 18VDC. The output voltage drops when loaded. If you intend to fully load (use the max. current available) the adapter, it might not have enough headroom to allow a typical 12 V regulator to regulate well. A 9V regulator will work fine.

BTW, what kind of microcontroller are you using that requires 12V to run? Just curious!



New Member
It is an motorola 6812 evaluation board. Let me quote the booklet word for word. " You can power the module in one of 2 ways:
1) supply power via the external power connecter; just connect a DC voltage of 8 Volts or more ( Maximum 12V) to the external power connector J1. Red is positive, and black is negative( ground). CAUTION! Make sure you have the polarity correct!
2) or, supply regulated 5VDC via the appropriate pins on the 50-pin connector ( H1). See Appendix A for the module pinout diagram. CAUTION!
Double-check your connections before applying power! "

The number 2 option doesnt make the slightest sence to me. How the hell am i sopposed to use the pins of the evboard to power the evboard itself? That does not make any sence. Anyway what is a regulalor and where can i find a used one. Used computer store? What do you suggest i do without spending $25.00 on the 9 V adapter that radio shack told me to buy. Im not spending so much on this. any suggestions?
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