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.

wrote:
1n914/4148 as silicon temperature sensor. (forward bias)
I used a 1n4007 as a temperature sensor to repair a water bed
heater.

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.

"Si Ballenger" wrote in message
...
On Fri, 25 Nov 2005 20:48:19 GMT, Al wrote:

In article ,
Paul Keinanen 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).

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"...

On Fri, 25 Nov 2005 22:13:38 -0500, Phil Hobbs
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.

John Devereux wrote in
:

ehsjr 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 antworten.

On Sat, 26 Nov 2005 11:56:55 +0200, Paul Keinanen
wrote:

On Fri, 25 Nov 2005 12:29:52 -0800, Roy Lewallen
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

1n914/4148 as silicon temperature sensor. (forward bias)

I used a 1n4007 as a temperature sensor to repair a water bed
heater.

What is the rest of the circuit you used?

--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)

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

Jim Thompson wrote:
On Fri, 25 Nov 2005 22:13:38 -0500, Phil Hobbs
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