Electronics Forum / Electronics / September 2008

I zapped an old Fluke 23 yesterday by inadvertantly applying about
several KV which burnt a 1 Megohm 5% carbon composition resistor which
is in series with an overvoltage MOV type thing with a split in it.
This resistor is connected to the + input.

Hi, I need to generate an RS232 signal from a TTL line. + & - 12v supplies
available, and the setup must be low current draw. Currently I'm using 8 pin
DIP SN75155s, neet footprint but the quiescent current drain is over 8mA
which is too high here. 1488s are even higher. The ...

This is a new design for Gyroscopic Inductance circuit for DC current
production using the gyroscope itself as the induction circuit for
long term space flight. It will produce Direct current from a
gyroscope functioning in a zero gravitational field as an inductance

hi , i have 19 rows of   four , 10mm white leds.  would it be better to
power them  straight from dc or a pwm supply ?
thanks
mark k

It seems to me that a flourescent ballast is probably just a transformer and
a high-voltage electrolytic cap.  And when it "goes out" it's probably
because the cap failed.  If these are true, could I just replace the cap and
make it work again?  Assuming (hate that word) of ...

for a home project I'm looking for ultrasonic speakers (tweeters) with a
frequency range of more than 30 KHz with a power of about 100W.
Where can I buy them?
Thanks,

i am devang bhavsar.
i am interested to join your group.
plese accept me..!

I'm interested in measuring amperage in three phase equipment
with three Jaycar current sensing clamps that can output 10mV/Amp.
  I have to feed a DC input data logger so I built an opamp based
peak detector which outputs a smooth DC voltage that matches the

Farnell have always gone a bit overboard on packaging, but my latest
shipment I thought was just silly.
Some SMD resistors back ordered from the US (Newark) arrived in the
usual courier bag, inside of which was a padded #0 jiffy bag for EACH

Hi, I cooked my K150 (kits-R-us) PIC programmer last night by inadvertently
putting a PIC backwards into the ZIF. There was a slight burning smell, and
from then on it won't read or program devices. I checked the associated
website, and it mentions that the programming switch ...

Over on a web forum [1] someone asked about some of the older logic
chips that required multiple supplies and it's been bothering me that I
can't find out the answer.
Some NMOS chips like the 8080 needed an extra negative (-5) and more-

I recently replaced the magnetron on a microwave.
It was a Panasonic inverter type. Some suggest it could
be the inverter or the magnetron. I decided to go buy
a new magnetron from Prime Electronics and replaced it.

A company that is not a phone co. offered a contract for stand alone
DSL.
1) If DSL is always on, does that mean that you're connected to the
Internet everytime the machine is booted up?  Isn't there a switch to

In fact , fakes are everywhere. but why they cant  be totally
forbidded?  and why still so many many  B2B platforms exist?  and  the
most important  is why there still a very big market of fakes?  all
these why ? who can tell me? Maybe all ppl know that bcz of the needs

...power out...reboot...power out...reboot...turn off...turn on...no
text on screen,
motherboard not booting...cmos battery out/in...no booting...remember
strange