Unusual functions of cheap parts

[Paul Keinanen]

On Fri, 25 Nov 2005 12:29:52 -0800, Roy Lewallen <w7el@eznec.com>
wrote:

Paul Keinanen wrote:
. . .
You must have quite slow fuses in 110 V land if you can do a reliable
ignition without blowing the fuse. For 230 V operation, I would
suggest using a current limiting resistor (such as a large heater) or
an inductance (such as fluorescent light ballast) during the ignition.
When there is a solid arc, the current limiter can be shorted out.


Aren't you in danger of damaging your eyes from the UV emitted from the arc?

Certainly.

I used arc welding glasses when conducing these experiments.

Some trivia:

In the silent film era, actors had eye problems due to the UV
radiation from arc studio lamps.

Most of the usable illumination from the arc lights is actually from
the glowing carbon electrodes.

"Automatic arc lights" used a solenoid in series with the arc to keep
the distance constant between the poles regardless of carbon electrode
burnout. I assume that if this is to be used with a AC arc light, both
the moving coil as well as the static coil should carry the arc
current.

Paul OH3LWR

 

[Murray]

Frithiof Andreas Jensen wrote:

"Henry Kiefer" <otc_friend@gmx.net> skrev i en meddelelse
news:4385b3b1$1$27887$9b4e6d93@newsread4.arcor-online.net...


Do you know of other interesting devices or circuits good for misuse?


Unbuffered logic gates can make a really bad but still useful analogue
amplifier by adding feedback and bias.


E.G the CMOS 4007. See the old handbooks for a '100dB

amplifier' based on a RCA chip - there was a wiring
error in that old description - IIRC it was 3800? -
whatever, the 4007 is the same chip.

Murray vk4aok

 

[Paul Keinanen]

On Sat, 26 Nov 2005 21:19:18 +1000, Murray <me@erewhon.net> wrote:

Frithiof Andreas Jensen wrote:

E.G the CMOS 4007. See the old handbooks for a '100dB
amplifier' based on a RCA chip - there was a wiring
error in that old description - IIRC it was 3800? -
whatever, the 4007 is the same chip.

The Motorola McMOS handbook (2nd edition 1974) warns about this usage
by pointing out that by cascading three such AC coupled stages, the
last stage will be saturated by the noise from the first stage.

Paul OH3LWR

 

[wa2mze(spamless)]

Stefan Heimers wrote:

Henry Kiefer wrote:


Do you know of other interesting devices or circuits good for misuse?


I never tried it myself, but I heard that some people abused opened memory
chips as cameras, back when CCD camera chips were too expensive for
hobbyists.

http://www.classiccmp.org/pipermail/cctalk/2004-May/042581.html

http://groups.google.com/group/comp.robotics.misc/browse_thread/thread/652cc4b0e1ccee57/f84b0f2d5c0b6da7?lnk=st&q=opened+RAM+chips+used+as+camera&rnum=6#f84b0f2d5c0b6da7

Yes, a co-worker at a former job and myself peeled the top off a 22pin dram chip

(we went through several brands to find one that had the memory array in one
large area rather then 4 smaller areas) and then replaced the top with a microscope
slide cover. By re-reading the array and timing how long it took for the
ones to decay to zeros (or visa versa) we were able to get about 4 levels of
gray scale. A tiny lens from a broken camera view finder was mounted above the
chip and I rigged up a way to move the chip back and forth to focus. Our first
'subject' was a 60w light bulb. We were using an AppleII (gives you an idea
of how long ago this was) to do the image processing. We both went 'crazy'
when we saw the '60 Watt' from the top of the bulb on the screen!
The resolution of our camera wasn't even as good as early SSTV (maybe 64 x 64
pixels) but it did work.

 

[wa2mze(spamless)]

Henry Kiefer wrote:

Hi all -

After my first thread going from "standard" cheap parts for up to vhf
frequency to a discussion about the usefulness of Spice simulator...... I
try it another time hopefully get attention of frustrated co-readers:

For example the rechtifier diode 1N4007 can be used as a rf switching diode,
for example as rx/tx-switch. This is because it is a pin structure diode.
This type is cheap and you can get it almost everywhere. It shows good
performance for the price. Surely for high-end you should do it with another
type tuned to the application it is made for. But anyway it works in some
circuits.

Do you know of other interesting devices or circuits good for misuse?

Best regards -
Henry


Take one P channel Jfet and one N channel Jfet and connect them

in series so the two sources are together, connect the gate of
each transistor to the other one's drain. This is known as a lambda
connection, and if you plot the voltage vs current from drain to drain
you will see a negative resistance region, usually around 3v
(depending on the transistors). The circuit will work as a tunnel
diode oscillator up to 100-200mhz.

 

[wa2mze(spamless)]

You must have quite slow fuses in 110 V land if you can do a reliable
ignition without blowing the fuse. For 230 V operation, I would
suggest using a current limiting resistor (such as a large heater) or
an inductance (such as fluorescent light ballast) during the ignition.
When there is a solid arc, the current limiter can be shorted out.

Paul

Did you know that a carbon arc acts as a negative resistance? Run the
arc on DC and put an LC tuned circuit in series with the arc (coil of
heavy copper tubing) and you have a powerful oscillator.

 

[Rick]

"Si Ballenger" <shb*NO*SPAM*@comporium.net> wrote in message
news:4387be6d.204451325@news.comporium.net...

On Fri, 25 Nov 2005 20:48:19 GMT, Al <no.spam@wanted.com> wrote:

In article <clieo1lq869ialc6um02omsfdt266dvr2c@4ax.com>,
Paul Keinanen <keinanen@sci.fi> wrote:

On Thu, 24 Nov 2005 18:49:24 -0500, Jon Yaeger
jono_1@bellsouth.net
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).

The problem is that the carbon rod conducts heat quite well, so
after
a while, any wooden object will catch fire .

Tap the free ends of the rods together. Move them apart as
necessary.

You must have quite slow fuses in 110 V land if you can do a
reliable
ignition without blowing the fuse. For 230 V operation, I would
suggest using a current limiting resistor (such as a large
heater) or
an inductance (such as fluorescent light ballast) during the
ignition.
When there is a solid arc, the current limiter can be shorted
out.

Paul


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.

Exactly-when I was a kid we made them like this all the time. As I
recall, it came from "700 scientific experiments, with
illustrations"...

>

 

[Jim Thompson]

On Fri, 25 Nov 2005 22:13:38 -0500, Phil Hobbs
<pcdhSpamMeSenseless@us.ibm.com> wrote:

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.

Cheers,

Phil Hobbs

I've used a light bulb in series with a rectifier to charge a car
battery (just make sure that line ground goes to chassis ground ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Matthias Weingart]

John Devereux <jdREMOVE@THISdevereux.me.uk> wrote in
news:8764qh82fw.fsf@cordelia.devereux.me.uk:

ehsjr <ehsjr@bellatlantic.net> writes:
Henry Kiefer wrote:
Do you know of other interesting devices or circuits good for
misuse? Best regards -
Henry

An LED as a shunt regulator. Also, as a varicap.
Ed

Also a photodetector that is insensitive to long wavelengths
(because of the high bandgap).

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

M.
--
Bitte auf mwnews2@pentax.boerde.de antworten.

 

[John Larkin]

On Sat, 26 Nov 2005 11:56:55 +0200, Paul Keinanen <keinanen@sci.fi>
wrote:

On Fri, 25 Nov 2005 12:29:52 -0800, Roy Lewallen <w7el@eznec.com
wrote:

Paul Keinanen wrote:
. . .
You must have quite slow fuses in 110 V land if you can do a reliable
ignition without blowing the fuse. For 230 V operation, I would
suggest using a current limiting resistor (such as a large heater) or
an inductance (such as fluorescent light ballast) during the ignition.
When there is a solid arc, the current limiter can be shorted out.


Aren't you in danger of damaging your eyes from the UV emitted from the arc?

Certainly.

I used arc welding glasses when conducing these experiments.

Some trivia:

In the silent film era, actors had eye problems due to the UV
radiation from arc studio lamps.

Most of the usable illumination from the arc lights is actually from
the glowing carbon electrodes.

"Automatic arc lights" used a solenoid in series with the arc to keep
the distance constant between the poles regardless of carbon electrode
burnout. I assume that if this is to be used with a AC arc light, both
the moving coil as well as the static coil should carry the arc
current.

Paul OH3LWR

We worked with a company that was developing an xray imager, and was
buying very expensive electrically conductive glass (gigohms per
square sort of range.) They discovered that certain welding glass was
identical and about 1/20 the price.

John

 

[Oliver Betz]

"Henry Kiefer" <otc_friend@gmx.net> wrote:

[...]

If you need a zener diode with very low noise you can use LEDs. That has the

you mean forward biased? Reverse breakdown of most cheap LEDs is IIRC
around 100V.

Oliver
--
Oliver Betz, Muenchen (oliverbetz.de)

 

[Winfried Salomon]

Hello Jorgen,

Jorgen Lund-Nielsen wrote:

[.....]

2N2369 for fast pulses.

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.

mfg. Winfried

 

[John - KD5YI]

Jim Thompson wrote:

On Fri, 25 Nov 2005 22:13:38 -0500, Phil Hobbs
pcdhSpamMeSenseless@us.ibm.com> wrote:


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.

Cheers,

Phil Hobbs


I've used a light bulb in series with a rectifier to charge a car
battery (just make sure that line ground goes to chassis ground ;-)

...Jim Thompson

Going the other direction, I used the elements from a toaster as a load to
discharge wet-cell lead-acid batteries. It was a discharge/charge cycling test.

John

 

[Jim Thompson]

On Sat, 26 Nov 2005 21:41:06 +0100, Winfried Salomon
<wsalomontrashcan@t-online.de> wrote:

Hello Jorgen,

Jorgen Lund-Nielsen wrote:

[.....]
2N2369 for fast pulses.

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.

mfg. Winfried

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.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Henry Kiefer]

As a youngster I played with TTL DIP-ICs in my chamber and my parents next
room felt that the tv was going crazy. The pins had long wires...

- Henry

<skavanagh72nospam@yahoo.ca> schrieb im Newsbeitrag
news:1132928901.255333.129630@g43g2000cwa.googlegroups.com...

As an addition to the various mentions of common diodes as varactors
there is a well publicized British design for a frequency tripler that
will put out 2 watts at 1.3 GHz and uses five 1N914's in parallel.

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.

 

[Henry Kiefer]

The 4007 is the classic crystal oscillator circuit.
Don't forget the temperature characteristics!

- Henry

"Murray" <me@erewhon.net> schrieb im Newsbeitrag
news:43884488$0$12455$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

Frithiof Andreas Jensen wrote:

"Henry Kiefer" <otc_friend@gmx.net> skrev i en meddelelse
news:4385b3b1$1$27887$9b4e6d93@newsread4.arcor-online.net...


Do you know of other interesting devices or circuits good for misuse?


Unbuffered logic gates can make a really bad but still useful analogue
amplifier by adding feedback and bias.


E.G the CMOS 4007. See the old handbooks for a '100dB
amplifier' based on a RCA chip - there was a wiring
error in that old description - IIRC it was 3800? -
whatever, the 4007 is the same chip.

Murray vk4aok

 

[Henry Kiefer]

That is not new to me but thanks!
Is the oscillator useful at 150MegHz? Modulable? Maybe I can make
transmitter...
Tell us more, please.

cu -
Henry


"wa2mze(spamless)" <"wa2mze(spamless)"@bellsouth.net> schrieb im Newsbeitrag
news:tT_hf.27576$s92.24482@bignews6.bellsouth.net...

Henry Kiefer wrote:
Hi all -

After my first thread going from "standard" cheap parts for up to vhf
frequency to a discussion about the usefulness of Spice simulator......
I
try it another time hopefully get attention of frustrated co-readers:

For example the rechtifier diode 1N4007 can be used as a rf switching
diode,
for example as rx/tx-switch. This is because it is a pin structure
diode.
This type is cheap and you can get it almost everywhere. It shows good
performance for the price. Surely for high-end you should do it with
another
type tuned to the application it is made for. But anyway it works in
some
circuits.

Do you know of other interesting devices or circuits good for misuse?

Best regards -
Henry


Take one P channel Jfet and one N channel Jfet and connect them
in series so the two sources are together, connect the gate of
each transistor to the other one's drain. This is known as a lambda
connection, and if you plot the voltage vs current from drain to drain
you will see a negative resistance region, usually around 3v
(depending on the transistors). The circuit will work as a tunnel
diode oscillator up to 100-200mhz.

 

[Henry Kiefer]

Don't forget the LED as an low-noise zener diode with integrated function
control. Some high-fidelity enthusiasts use this in good audio amplifiers.

- Henry

"ehsjr" <ehsjr@bellatlantic.net> schrieb im Newsbeitrag
news:R3thf.9922$BU2.983@trndny01...

Henry Kiefer wrote:
Hi all -

After my first thread going from "standard" cheap parts for up to vhf
frequency to a discussion about the usefulness of Spice simulator......
I
try it another time hopefully get attention of frustrated co-readers:

For example the rechtifier diode 1N4007 can be used as a rf switching
diode,
for example as rx/tx-switch. This is because it is a pin structure
diode.
This type is cheap and you can get it almost everywhere. It shows good
performance for the price. Surely for high-end you should do it with
another
type tuned to the application it is made for. But anyway it works in
some
circuits.

Do you know of other interesting devices or circuits good for misuse?

Best regards -
Henry



An LED as a shunt regulator. Also, as a varicap.
Ed

 

[Henry Kiefer]

There even exists LED specially taylored to the needs of doing duplex
operation.

- Henry


"Frithiof Andreas Jensen" <frithiof.jensen@die_spammer_die.ericsson.com>
schrieb im Newsbeitrag news:dm6msq$bvk$1@news.al.sw.ericsson.se...

"Henry Kiefer" <otc_friend@gmx.net> wrote in message
news:4385b3b1$1$27887$9b4e6d93@newsread4.arcor-online.net...

Do you know of other interesting devices or circuits good for misuse?

LED's work both ways, as a light emitter and a photodiode.

The inbuilt colour filter can be used to distinguish between Grass and Not
grass f.ex. by comparing output from a red and a green LED using white
light
as illumination.

Back when fiber was ex$$$pensive one often saw clever circuitry using two
transmitters to form a duplex connection over a single fiber.

The USD 10 solar powered garden lamps will, with a little persuation,
yield
a nice solar cell well below the price of a similar unit in the shops -
and - two 600 mAh NiMh batteries and a grotty circuit for switching the
LED.

 

[Henry Kiefer]

Bob Pease of National Semi mentioned a ONE AND ONLY transistor circuit
above/under voltage rail converter (with detailed theory). I cannot remember
the details. But interesting if sometime a slightly voltage behind the power
rail is needed. For example to power a CMOS Opamp now doing rail-input.

- Henry