using adapter as dc supply

[fugrammer]

hi. i am building a circuit that requires 12vdc and a few amp. My original plan was to use a adapter capable of delivering that amount of power. However, althought its output is rated as 12v, i measured 18v. Can i still use it for the circuit? And why is the difference is huge?

[Steve Joblin]

AC Adaptors (or "wall warts" as they are often called) are usually unregulated.  You usually need to run the power from these through a voltage regulator to get the precise voltage you want.  You will also need a few filter capacitors as well to ensure a clean, consistent supply.  Depending on what your circuit is, you may need to attach a heat sink to the voltage regulator.  If you provide a schematic or more details of your circuit, we can recommend a voltage regulator that would suit your needs.

[suren]

yeah you can used that ..i had a similar problem.What i did was to shift the adaptor output to 9 volts..and actually it gave me 11.5 volts..good enough right..try something like this in your adaptor too.