Unusual functions of cheap parts
 

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

Unusual functions of cheap parts
 

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/...ay/042581.html

http://groups.google.com/group/comp....4b0f2d5c0b6da7

Unusual functions of cheap parts
 

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

Tuner Switching Diodes like the european BA244 (NOT PIN-Diodes!) work
well as medium fast Step Recovery Diodes.

Jorgen

Unusual functions of cheap parts
 

Henry Kiefer wrote:
[...]
Do you know of other interesting devices or circuits good for misuse?

Take away the hat of a 2N3055 and use it as a light sensor (sensitive).

Robert

Best regards -
Henry

--
'Vom Standpunkt eines Beamtenrechtlers aus betrachtet ist der Tod die
schärfstwirkenste aller bekannten, langfristig wirkenden Formen der
vollständigen Dienstunfähigkeit.'
aus: Kommentar zum Beamtenrecht.

Unusual functions of cheap parts
 

On Thu, 24 Nov 2005 09:40:27 +0100, "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



A 1N4007 can also be used as a drift step-recovery diode and as a
plasma avalanche diode. Together, two can generate a kilovolt edge
with a 100 ps risetime.

GAASfets make good fast analog switches; they behave pretty much like
jfets.

Wide-open LDO regulators make nice resettable fuses.

Ferrite beads do all sorts of interesting stuff.

Power mosfets make good heaters, and TO-220 bipolar transistors make
nice temperature sensors.

LVDS line receivers are surprisingly good comparators, and *fast*


I could go on...

John

Unusual functions of cheap parts
 

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

The LM317 as a radio transmitter

http://web.telia.com/~u85920178/tx/317-tx.htm

Unusual functions of cheap parts
 

On Thu, 24 Nov 2005 18:30:06 +0100, Jorgen Lund-Nielsen
wrote:

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

Tuner Switching Diodes like the european BA244 (NOT PIN-Diodes!) work
well as medium fast Step Recovery Diodes.

Jorgen


I know a guy who uses surface-mount resistors as explosive detonators.

John

Unusual functions of cheap parts
 

On Thu, 24 Nov 2005 09:40:27 +0100, "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.
[snip]

Best regards -
Henry


That's an interesting use of the 1N4007. I've not tried that, what
kind of off capacitance do you get?

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

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

Unusual functions of cheap parts
 

Cadmium sulphide ( CdS ) LDR as a Beta radiation detector. Not sensitive to
Gamma radiation which can be an advantage because it will detect Beta in
presence of Gamma. You have to paint it black. Horrible temperature
sensitivity but you can use another CdS as reference.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

Unusual functions of cheap parts
 

On Thu, 24 Nov 2005 18:20:57 GMT, "CA" wrote:

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

The LM317 as a radio transmitter

http://web.telia.com/~u85920178/tx/317-tx.htm


Cool. 3T regulators, 317 and LM1117 types, can be neat power amps, for
driving unipolar loads like motors and such. Sort of a follower with a
largish offset.

Hmmm, an LM1117 followed by a monster darlington becomes a
super-follower with roughly zero offset.

John

Unusual functions of cheap parts
 

On Thu, 24 Nov 2005 18:30:06 +0100, Jorgen Lund-Nielsen
wrote:

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

Tuner Switching Diodes like the european BA244 (NOT PIN-Diodes!) work
well as medium fast Step Recovery Diodes.


Tell me about it. I tried some pins to see if they would snap, and
they turn out to have incredibly mushy reverse recovery, Slop Recovery
Diodes.

I'll have to try the varicaps.

John

Unusual functions of cheap parts
 

John Larkin wrote:

A 1N4007 can also be used as a drift step-recovery diode and as a
plasma avalanche diode. Together, two can generate a kilovolt edge
with a 100 ps risetime.

Okay, so I'm intrigued already. I have all the hardware available--two
1N4007s and a 3 kV adjustable power supply! How do I build one?

Cheers,

Phil Hobbs

Unusual functions of cheap parts
 

On Thu, 24 Nov 2005 09:40:27 +0100, "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

1n4007 as varactor (freq multiplier) and also Varicap.
You already mentioned RX/TX swich.
Also in PIN attenuator circuits.

Glass cased rectifiers (1n4007 in glass rather than epoxy)
as photodiode.

1n914 as 2ghz multipler (as varactor) to 100mw output.

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

Base emitter of NPN silicon transistors as Zeners (5-8Vrange).
Makes a decent noise diode that way too.

Base collector of NPN si transistor as Varicap

Collector emitter of silicon transistors reverse biased as negative
resistance device.

Open GE and SI transistors are sensitive photodetectors.

Opened SCRs as photoswitches.


Allison

Unusual functions of cheap parts
 

On Thu, 24 Nov 2005 14:47:37 -0500, Phil Hobbs
wrote:

John Larkin wrote:

A 1N4007 can also be used as a drift step-recovery diode and as a
plasma avalanche diode. Together, two can generate a kilovolt edge
with a 100 ps risetime.

Okay, so I'm intrigued already. I have all the hardware available--two
1N4007s and a 3 kV adjustable power supply! How do I build one?

Cheers,

Phil Hobbs

Google "Grekhov diode." A lot of the papers are for members only, but
this one gives the general idea:

http://www.ece.jhu.edu/~pps/ECE777/A...ano-pulse1.pdf

Grekhov discovered both the DSRD and the plasma avalanche effects in
cheap power diodes. The core of the DSRD effect is that, if a PIN
diode is forward biased for not too many nanoseconds, the carriers
don't have time to float all around the place so the charge profile is
good for a nice reverse snap. HP did the same thing in their classic
1430 12-GHz sampling head, circa 1965 roughly.

This box used the DSRD effect, in a semiconductor that one would not
expect to be used in an application like this...

http://www.highlandtechnology.com/DSS/T220DS.html

We bias the snap diode +48 volts (yes, forward direction) for about 80
ns before we turn the drive around for the snap. It was originally
designed for use in a LEAP atom probe.

John

Unusual functions of cheap parts
 

Hi,

2N3055: one-time trigger diode with abt. 160v triggering voltage
[had some ones of unknown state left from a PSU that blew one of 5
transistors, replaced them with MJ15003]

various, sometimes expensive components: firecrackers, smoke bombs,
lamps (most of the time unintended ;) )

old EPROMs: Lamp.Find some pins with low resistance and apply .5-2A.

the IC/transistor that was broken and took you some hours to find the
trouble:
Get 1-5 large caps (like 12 000µF 350V), charge them, and apply the
voltage to the part with a very large relay.
LOUD!

Unusual functions of cheap parts
 

Zener diodes work fine as varicaps, at least at HF. The lower the zener
voltage and higher the power dissipation rating, the higher the C. As
someone else mentioned, transistor emitter-base junctions can be used as
either zeners (typical zener voltage around 5 volts) or varicaps.

A zener can be used as a broadband noise source. I've had the best luck
with zeners of 10 - 15 volt breakdown, with around 100 uA current. Some
are noisier than others, and they often have a critical current where
the noise is the greatest.

Tektronix used selected transistors to generate high voltage (~100
volts) fast steps (~100 ps rise time if I recall correctly) by
avalanching the collector. Some fraction of some common transistor types
worked satisfactorily in this application.

1N914 type diodes can be used as step recovery diodes to generate a step
with about a ns risetime -- maybe faster with a chip component and some
care. This could be the basis of a broadband harmonic generator.

Roy Lewallen, W7EL

Unusual functions of cheap parts
 

) writes:

1n4007 as varactor (freq multiplier) and also Varicap.
That's not really a new thing, or specific to the 1N4007.

Sam Harris, in that first article about parametric amplifiers in
CQ circa 1958, goes into detail of what's required, and then
practically leaves the issue of the varactor to the end. At
the time, they were new, likely expensive, and not easy to get.
Sam had it easy, he worked at Microwave Associates at the time.
So then towards the end of the article where he attends to the
issue of the varactor, he basically says use whatever's available,
try things, and at least practice with those other devices until
you get good at it, at which point it's time for the "real thing".
I have quoted that bit in the past, but I don't know where I've
put the article to get the exact wording.

And ever since then, influenced by his words or maybe independent
thought, the magazines have been full of mention of using whatever's
available as a varactor, the results varying with the diode (or
junction, since some have used part of a transistor) and of course
the application.

And of course, there was one article where the author mentioned a lot
of hum in his six meter synthesizer that used something like a 1N914
for the varactor. He then realizes that the problem was the light
of a nearby lamp getting to the actual diode theough the glass
case of the diode, and hence modulating the VCO that way.

Michael VE2BVW

Unusual functions of cheap parts
 

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.

Jon

Unusual functions of cheap parts
 

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

Unusual functions of cheap parts
 

"ehsjr" bravely wrote to "All" (25 Nov 05 00:40:17)
--- on the heady topic of " Unusual functions of cheap parts"

eh From: ehsjr
eh rec.radio.amateur.homebrew:89241 sci.electronics.components:102765
eh sci.electronics.design:525790

eh 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

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


A TL431 precision bandgap voltage reference IC as a 400mW output
phono amplifier. It's in the application notes!

A*s*i*m*o*v

.... Marketing success has little to do with technical merit.

Unusual functions of cheap parts
 

On 2005-11-24, John Larkin wrote:
I know a guy who uses surface-mount resistors as explosive detonators.

I understand you can place a row of surface-mount capacitors along the
edge of a board so they will be scraped off by any accidental contact
with nearby sheetmetal.

--
Ben Jackson

http://www.ben.com/

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.

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.

---
Regards,
Bob Monsen

The question of the ultimate foundations and the ultimate meaning of
mathematics remains open; we do not know in what direction it will find its
final solution or even whether a final objective answer can be expected at
all. "Mathematizing" may well be a creative activity of man, like language
or music, of primary originality, whose historical decisions defy complete
objective rationalization.
- Hermann Weyl in 1944

Unusual functions of cheap parts
 

John Larkin wrote:

TO-220 bipolar transistors make nice temperature sensors.

I like that trick. Esp the isolated tab type.

Graham

Unusual functions of cheap parts
 

Roy Lewallen wrote:
Zener diodes work fine as varicaps, at least at HF. The lower the
zener voltage and higher the power dissipation rating, the higher the
C. As someone else mentioned, transistor emitter-base junctions can
be used as either zeners (typical zener voltage around 5 volts) or
varicaps.
A zener can be used as a broadband noise source. I've had the best
luck with zeners of 10 - 15 volt breakdown, with around 100 uA
current. Some are noisier than others, and they often have a critical
current where the noise is the greatest.

Tektronix used selected transistors to generate high voltage (~100
volts) fast steps (~100 ps rise time if I recall correctly) by
avalanching the collector. Some fraction of some common transistor
types worked satisfactorily in this application.

1N914 type diodes can be used as step recovery diodes to generate a
step with about a ns risetime -- maybe faster with a chip component
and some care. This could be the basis of a broadband harmonic
generator.
Roy Lewallen, W7EL

At a leading Ultrasonic flaw detector company we used simple low frequency
Motorola sot23 transistors in avalance mode for making a nice pulse
generator for 100MHz probes. These were better than the Zetex avalance
specified transistors.
--
ciao Ban
Apricale, Italy

Unusual functions of cheap parts
 

"Henry Kiefer" wrote in message
...

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.

Unusual functions of cheap parts
 

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).


--

John Devereux

Unusual functions of cheap parts
 

(not x-posted)

Besides the already mentioned reverse-polarized diodes as varicaps
(http://www.hanssummers.com/radio/varicap/index.htm), I use 74HC240 as
HF QRP finals (600mW) and IRF510 as HF PA (20-30W max, QST has some
articles in the past).

Paolo IK1ZYW

Unusual functions of cheap parts
 

Besides the already mentioned reverse-polarized diodes as varicaps
(http://www.hanssummers.com/radio/varicap/index.htm), I use 74HC240 as HF
QRP finals (600mW) and IRF510 as HF PA (20-30W max, QST has some articles
in the past).

Paolo IK1ZYW

TL-431 Shunt regulator as a low powered fixed gain 3 terminal audio
amplifier.

W4ZCB

Unusual functions of cheap parts
 

John Larkin wrote:
On Thu, 24 Nov 2005 18:30:06 +0100, Jorgen Lund-Nielsen
wrote:


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

Tuner Switching Diodes like the european BA244 (NOT PIN-Diodes!) work
well as medium fast Step Recovery Diodes.



Tell me about it. I tried some pins to see if they would snap, and
they turn out to have incredibly mushy reverse recovery, Slop Recovery
Diodes.

I'll have to try the varicaps.

John

Hello John,

I wrote: NOT PIN - Diodes - as they wouldn't snap.

i mean Band Switching diodes for TV-Tuners like the BA244 and the BA682.

BA682 Datasheet:

http://www.vishay.com/docs/85530/85530.pdf

- and they snap! Try it!

Jorgen
dj0ud

Unusual functions of cheap parts
 

Ban wrote:

Roy Lewallen wrote:

Zener diodes work fine as varicaps, at least at HF. The lower the
zener voltage and higher the power dissipation rating, the higher the
C. As someone else mentioned, transistor emitter-base junctions can
be used as either zeners (typical zener voltage around 5 volts) or
varicaps.
A zener can be used as a broadband noise source. I've had the best
luck with zeners of 10 - 15 volt breakdown, with around 100 uA
current. Some are noisier than others, and they often have a critical
current where the noise is the greatest.

Tektronix used selected transistors to generate high voltage (~100
volts) fast steps (~100 ps rise time if I recall correctly) by
avalanching the collector. Some fraction of some common transistor
types worked satisfactorily in this application.

1N914 type diodes can be used as step recovery diodes to generate a
step with about a ns risetime -- maybe faster with a chip component
and some care. This could be the basis of a broadband harmonic
generator.
Roy Lewallen, W7EL


At a leading Ultrasonic flaw detector company we used simple low frequency
Motorola sot23 transistors in avalance mode for making a nice pulse
generator for 100MHz probes. These were better than the Zetex avalance
specified transistors.

2N2369 for fast pulses.
2N2222 and even 2N2219 works, but a bit slower and they requiring more
voltage to avalance, but still 1nS rt
The Zetex are slower but can deliver much more current (up to 60A, ZTX
415 family).

Jorgen

Unusual functions of cheap parts
 

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.

Unusual functions of cheap parts
 

And by varying the reverse bias through a current source (or moderately
large fixed resistor) you can make them into nifty phase shifters.

Jim


I wrote: NOT PIN - Diodes - as they wouldn't snap.

i mean Band Switching diodes for TV-Tuners like the BA244 and the BA682.

BA682 Datasheet:

http://www.vishay.com/docs/85530/85530.pdf

- and they snap! Try it!

Jorgen
dj0ud

Unusual functions of cheap parts
 

Take a crystal for which you need a constant temperature. Solder the
cathode of a cheap diode (1N4148 etc.) to the crystal case. Solder one end
of a moderately low value half-watt resistor to the case. Bring out the
anode of the diode, the free end of the resistor, and the crystal case on
wire leads and encapsulate the crystal-diode-resistor in heat shrink. Use
the diode as your temperature sensor, the resistor as your heating element,
an opamp/driver transistor as the comparator/amplifier and bingo, the
world's cheapest crystal oven. Bang-bang or linear, your choice.

Jim



eh Henry Kiefer wrote:
Hi all -


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

Best regards -
Henry

Unusual functions of cheap parts
 

"Henry Kiefer" skrev i en meddelelse
...

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.

Unusual functions of cheap parts
 

On Fri, 25 Nov 2005 12:46:17 +0100, Jorgen Lund-Nielsen
wrote:

John Larkin wrote:
On Thu, 24 Nov 2005 18:30:06 +0100, Jorgen Lund-Nielsen
wrote:


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

Tuner Switching Diodes like the european BA244 (NOT PIN-Diodes!) work
well as medium fast Step Recovery Diodes.



Tell me about it. I tried some pins to see if they would snap, and
they turn out to have incredibly mushy reverse recovery, Slop Recovery
Diodes.

I'll have to try the varicaps.

John

Hello John,

I wrote: NOT PIN - Diodes - as they wouldn't snap.


I got that!

i mean Band Switching diodes for TV-Tuners like the BA244 and the BA682.

BA682 Datasheet:

http://www.vishay.com/docs/85530/85530.pdf

- and they snap! Try it!

OK, I'll try some.


Thanks

John

Unusual functions of cheap parts
 

On Fri, 25 Nov 2005 09:07:38 +0000, Pooh Bear
wrote:



John Larkin wrote:

TO-220 bipolar transistors make nice temperature sensors.

I like that trick. Esp the isolated tab type.

Graham

There's also an LM35 in a TO-220 package! Ideal way to monitor a
heatsink.

John

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).

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

Unusual functions of cheap parts
 

Our newspaper had an article on that.
Also, for model rockets, burning up an ordinary resistor can be used as a
super-cheap ignitor.
Best---
Ron

John Larkin wrote in message
...
On Thu, 24 Nov 2005 18:30:06 +0100, Jorgen Lund-Nielsen
wrote:

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

Tuner Switching Diodes like the european BA244 (NOT PIN-Diodes!) work
well as medium fast Step Recovery Diodes.

Jorgen


I know a guy who uses surface-mount resistors as explosive detonators.

John

Unusual functions of cheap parts
 

John Larkin wrote:

A 1N4007 can also be used as a drift step-recovery diode and as a
plasma avalanche diode. Together, two can generate a kilovolt edge
with a 100 ps risetime.

GAASfets make good fast analog switches; they behave pretty much like
jfets.

Wide-open LDO regulators make nice resettable fuses.

Ferrite beads do all sorts of interesting stuff.

Power mosfets make good heaters, and TO-220 bipolar transistors make
nice temperature sensors.

LVDS line receivers are surprisingly good comparators, and *fast*


I could go on...

John

tell us more John

NT

Unusual functions of cheap parts
 

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?

Roy Lewallen, W7EL