| Chronology | Current Month | Current Thread | Current Date |
| [Year List] [Month List (current year)] | [Date Index] [Thread Index] | [Thread Prev] [Thread Next] | [Date Prev] [Date Next] |
On Wed, 6 Dec 2000, Larry Smith wrote:
I'm curious too. For our astronomy class we run two Meade telescopes which
call for 18 VDC from the car battery. There is a (literally) black box
which has one end labeled 18 V and the other end 12 V.
That might just be a "series regulator", where a transistor in series with
the +18V wire causes a voltage drop to 12v on the output. The transistor
actually forms a resistive voltage divider along with the external load
resistance. There is a feedback circuit as part of this, and the
transistor is constantly adjusted so that the voltage-division will always
produce 12VDC output. If you open up the black box, you might find an
even smaller black box, since these sorts of regulators often are entirely
built into the package of a single power transistor.