sort of voltage converter using a 12 V
gel cell. Does anyone know of a
simple circuit for accomplishing this?
#2048 Mark Warner
I am an electronics teacher
hunting for electronics jokes to use in
class. The cornier the better! I am
already using the "mobile ohm" and
"ohm ohm on the range," to give you
an idea of what is working.
#2049 Dave Brett
(Bring 'em on! — Editor Dan)
Does anyone have a simple
circuit to test for continuity up to a
few hundred ohms? I know these are
built into most digital voltmeters, but I
want a small, knock-around unit.
(Read TJ Byer's column in the January
issue — Editor Dan)
several minutes if you are just
disconnecting the battery. The
computer should return to the factory
default, with no password protection.
When done, replace the battery or
jumper, so that the computer can
remember other settings, such as
hard disk type and time.
#2 There are zillions of sites where
you can download software for BIOS
password recovery, such as
I have a surplus VFD display
module that I'd like to use in a club
project, but it has no specs. It looks
like one of those large cash register
displays that's mounted on a pole.
Inside is a pair of Futaba
M202LD01DA vacuum fluorescent
displays. The interface cable has
eight pins where 20 VDC power is
applied and an RS-485 serial interface
is used to talk to the modules. Futaba
was unable to help, can anyone else?
#20410 Kelly Small
[11038 - November 2003]
Ihave some Gateway 2000
4DX-66V computers that have a
BIOS password that prevents them
from booting. Is there a master
password that I can use to get in?
I am about to purchase a DVD
recorder/player; however, there are so
many supported formats that I need
help understanding the differences. A
sales person at a consumer
electronics outlet told me there were
three formats — plus, minus, and
progressive — but could not describe
any of them. I know what progressive
scan is, but what about the other two?
I do not understand how a disc
recorded in progressive scan can be
played back on an interlaced monitor.
Can anyone direct me to a source
that can give me the facts without
trying to sell me something?
#20411 E.A. Hill
#1 Generally, there is not a master
password. There is, however, an
alternate solution. You need to force
the system to forget that it is
password protected. This is done by
generating an invalid checksum to
force erase the CMOS RAM. Either
remove the backup battery or find the
jumper on the motherboard that
enables power to the CMOS memory
and remove it. It will be physically
close to the battery and the CMOS.
Some motherboards have a
three pin header. The center pin is
common. The outer pins are normal
operation and erase. Move the header
from one side to the other. It may take
#3 The easiest way to access a
password-protected BIOS setup is to
remove the backup battery for a few
minutes. This will reset all of the
CMOS settings, including the
password. You will then be able to
access the BIOS, but you will also
need to reset all of the hardware
settings, such as the hard drive type
and floppy drive configuration.
Backup batteries vary by
motherboard vintage. Older
motherboards have an external
battery pack, which is connected to
the motherboard by a header. Just
remove the header for a bit and then
replace it. Newer motherboards use a
The World”s Smallest
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I would like to build an engine
governor for my R/C helicopter, using
a set of points and the existing
throttle servo. I have been
experimenting with 555 ICs as the
timing device. Does anyone know of a
circuit I could use?
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