Unusual functions of cheap parts
 

Martin wrote in
:

To save power, use the LEDs of a backlight to measure the ambient
light to decide to switch the backlight on or not.

But how to decide to switch it off? I think there you have to
sample - switch of for a short time and test. This could give a
flickering backlight.

Ok, you found the skeleton in the closet. :-) You can not use
this method to switch it off - but it is not required in most cases.
Think of a cell phone - the backlight goes on every time you press a
key, and it is going off after 10 seconds.

M.
--
Bitte auf antworten.

Unusual functions of cheap parts
 

Am Sun, 27 Nov 2005 09:57:23 +0000 (UTC) schrieb Matthias Weingart
:

Martin wrote in
:

To save power, use the LEDs of a backlight to measure the ambient
light to decide to switch the backlight on or not.

But how to decide to switch it off? I think there you have to
sample - switch of for a short time and test. This could give a
flickering backlight.
Ok, you found the skeleton in the closet. :-) You can not use
this method to switch it off - but it is not required in most cases.
Think of a cell phone - the backlight goes on every time you press a
key, and it is going off after 10 seconds.

OK, so you can decide to not switch it on and save some mAs.

--
Martin

Unusual functions of cheap parts
 

Martin wrote:

I once built an HF transceiver that used CMOS logic chips for all
functions except an audio low noise amp and a voltage regulator...with
further thought those two could likely be done with CMOS logic too.

At least the audio amp, this is nice to build with some Inverters (4069)
with resistive Feedback.

Most of the audio section was done that way. But the product detector
had low impedance output and the CMOS amp was too noisy at 50 ohms. A
transformer might have done the job but a common-base amp seemed more
practical and less prone to picking up hum.

Steve

Unusual functions of cheap parts
 

Unusual functions of cheap parts
 

In article ,
Ivan Makarov wrote:

When I was a teenager and my brothers started bothering me with their loud
TV, I took a 220V relay, put one of the coil leads through its normally
closed contact group, and plugged the relay into the mains behind the wall
where the TV was. Made an exelent TVI/RFI generator, I thought the TV is
going to blow up.

#chuckle#

Back when I was living in a college dorm, the guy in the next room had
pretensions of being a musician - specifically, a drummer. His way of
"practicing" was to turn up his stereo - really loud - so he could
feel the bass, then put on headphones (so that the highs wouldn't hurt
his ears) and then drum along with the music.

Needless to say, this did not make him popular with me or my roommate,
the people on the other side of his room, or the folks downstairs (or,
I suspect, people in the next county). Numerous complaints were filed;
he kept on drumming.

The guy on the other side realized that the drummer's stereo was
plugged into an outlet on one side of their shared wall, and that he
had an outlet on the same circuit. The next time the booming started
up, he plugged his old fluorescent desk light into the outlet, and
then started vibrating his thumb on the pushbutton make/break "start"
switch.

BRRZZBuzzzBZAP.

Stereo goes off suddenly. Two minutes of blessed silence. Stereo
goes back on and the drumming starts again.

BURZZRfffBUZZT.

Lather, rinse, repeat. Eventually, the drummer gives up for the day.

I understand that the drummer never did figure out what was wrong with
the stereo, despite two trips to the repair depot. He left the dorm
at the end of the quarter (I suspect he was "asked" to depart by the
Powers That Be) and we could sleep and study in peace once again.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Unusual functions of cheap parts
 

Am Sat, 26 Nov 2005 22:35:18 -0500 schrieb Phil Hobbs
:

Martin wrote:
Am Fri, 25 Nov 2005 22:13:38 -0500 schrieb Phil Hobbs
:

Si Ballenger wrote:

I would put a 100 watt lamp in series thereby limiting the current.
I would shave the ends down to points so they heated up rapidly. I
put them into a hollowed out fire brick and made a cheap furnace.
Of course don't look at it; it's like looking at the sun.

The current limiter I saw used a glass pie pan with pieces copper
metal on each side with salty water as the electrolyte. It would
start to steam some when in operation. The furnace was a small
clay flower pot with holes in each side with the carbon rods
sticking inside until they touched.


As a boy, I used an electric teakettle as a ballast for a two-D-cell
carbon arc lamp--worked great.

An electric arc with just 3V from two D-cells? I thought the arc needs
at lesat 20V burning voltage.


It ran off 120 V. Parse the sentence as "two D-cell-carbon arc lamp."
An earlier poster talked about building AC-powered arc lamps using the
carbon rods from dry cells.

OK :-) I liked to do that myself, but not from our 230V mains power, but
with a transformer, 22V, and 30A short circuit.
--
Martin

Unusual functions of cheap parts
 

Many years ago, I lived on the 2nd floor of a 3-story apartment
building. A guy moved in above me who worked some strange shift such
that he generally slept during the day, and at night, when the rest of
us were trying to sleep, he'd blast his stereo until the early dawn. I
tried reasoning with him a few times, but when it became evident that he
didn't care about anyone but himself, I decided that he needed a taste
of his own medicine.

I wired up a 555 timer, a driver transistor, and a 12-volt solenoid that
I had harvested out of an old VCR. The body of the solenoid was fitted
with a couple of alligator clips, so that the coil could be attached to
grill of a heating duct near the ceiling of my apartment. Every half
minute or so, (adjustable with a pot) the timer would fire and the
solenoid would contract, making a loud, obnoxious ker-chunk that
resonated through the furnace duct.

Whenever I left the apartment for work, I'd install the gizmo on the
vent, and let it run all day while the guy upstairs was trying to sleep.
The beauty of it was that the guy above could not complain about
anything I was doing, he could only complain that the "furnace was
making strange noises" that kept him awake.

A couple of times the management asked to inspect my furnace, and of
course, I let them. Needless to say, the gizmo was turned off and had
been removed from the vent in preparation for their visit.

Eventually, in true Pavlov-ian fashion, the guy upstairs learned that
the strange "furnace noises" seemed to coincide with the abuse of his
stereo. He noticed that when his stereo kept me up at night, the
"furnace" kept him up during the day. Hmmm..... An unspoken
understanding was reached and everyone lived happily ever after.



Dave Platt wrote:
In article ,
Ivan Makarov wrote:


When I was a teenager and my brothers started bothering me with their loud
TV, I took a 220V relay, put one of the coil leads through its normally
closed contact group, and plugged the relay into the mains behind the wall
where the TV was. Made an exelent TVI/RFI generator, I thought the TV is
going to blow up.


#chuckle#

Back when I was living in a college dorm, the guy in the next room had
pretensions of being a musician - specifically, a drummer. His way of
"practicing" was to turn up his stereo - really loud - so he could
feel the bass, then put on headphones (so that the highs wouldn't hurt
his ears) and then drum along with the music.

Needless to say, this did not make him popular with me or my roommate,
the people on the other side of his room, or the folks downstairs (or,
I suspect, people in the next county). Numerous complaints were filed;
he kept on drumming.

The guy on the other side realized that the drummer's stereo was
plugged into an outlet on one side of their shared wall, and that he
had an outlet on the same circuit. The next time the booming started
up, he plugged his old fluorescent desk light into the outlet, and
then started vibrating his thumb on the pushbutton make/break "start"
switch.

BRRZZBuzzzBZAP.

Stereo goes off suddenly. Two minutes of blessed silence. Stereo
goes back on and the drumming starts again.

BURZZRfffBUZZT.

Lather, rinse, repeat. Eventually, the drummer gives up for the day.

I understand that the drummer never did figure out what was wrong with
the stereo, despite two trips to the repair depot. He left the dorm
at the end of the quarter (I suspect he was "asked" to depart by the
Powers That Be) and we could sleep and study in peace once again.

Unusual functions of cheap parts
 

Hello Jim,

Jim Thompson wrote:
[...]
btw, do you know a standard complementary pnp-transistor for the 2N2369,
such like 2N3905 but with higher ft and less feedback capacitance? It
seems that the manufactorers have almost no data on their internet pages.

[...]


A 2N2369 is a gold-doped NPN, gold-doped to kill storage time and
improve recovery from saturation. I don't recall any PNP device with
gold-doping... or the equivalent.

thank you, then I suppose the 2N3905 oder 2N2905 are fitting for a large
signal amplifier.

mfg. Winfried

Unusual functions of cheap parts
 

On Thu, 24 Nov 2005 18:49:24 -0500, Jon Yaeger wrote:

Take apart a couple of D cell carbon-zinc batteries.

Wash off the carbon rods. Put each in a wooden clothes pin and connect the
attached ends to the mains voltage (US customers only, please).

Tap the free ends of the rods together. Move them apart as necessary. Very
bright! Much brighter than you are.

I put mine in series with Mom's iron, but the thermostat kept turning
it off.
--
Cheers!
Rich
------
"I don't drink water; fish **** in it."
-- W.C. Fields

Unusual functions of cheap parts
 

On Fri, 25 Nov 2005 00:43:52 -0800, Bob Monsen wrote:

On Thu, 24 Nov 2005 18:49:24 -0500, Jon Yaeger wrote:

Take apart a couple of D cell carbon-zinc batteries.

Wash off the carbon rods. Put each in a wooden clothes pin and connect the
attached ends to the mains voltage (US customers only, please).

Tap the free ends of the rods together. Move them apart as necessary. Very
bright! Much brighter than you are.

One of the MIT EE course videos on the web shows a demonstration of AC
across a pickle... it is an interesting effect. Not sure how the pickle
tastes afterward. Cooking hotdogs with AC is similar, but the pickle gives
off a much nicer translucent flickering glow. Very pretty.


But who wants a cooked pickle? ;-)

Thanks,
Rich