| Author |
Message |
Robert Obermayer
Guest
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 Posted:
Fri Nov 25, 2005 1:35 am Post subject:
Re: Unusual functions of cheap parts |
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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!
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John Larkin
Guest
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| Posted:
Fri Nov 25, 2005 1:35 am Post subject:
Re: Unusual functions of cheap parts |
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On Thu, 24 Nov 2005 18:20:57 GMT, "CA" <no@mail.com> wrote:
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 |
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Bob Monsen
Guest
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| Posted:
Fri Nov 25, 2005 9:35 am Post subject:
Re: Unusual functions of cheap parts |
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On Thu, 24 Nov 2005 18:49:24 -0500, Jon Yaeger wrote:
| Quote: | 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
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Pooh Bear
Guest
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| Posted:
Fri Nov 25, 2005 9:35 am Post subject:
Re: Unusual functions of cheap parts |
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John Larkin wrote:
| Quote: | TO-220 bipolar transistors make nice temperature sensors.
|
I like that trick. Esp the isolated tab type.
Graham |
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Ban
Guest
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| Posted:
Fri Nov 25, 2005 3:46 pm Post subject:
Re: Unusual functions of cheap parts |
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|
Roy Lewallen wrote:
| Quote: | 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 |
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Frithiof Andreas Jensen
Guest
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| Posted:
Fri Nov 25, 2005 3:52 pm Post subject:
Re: Unusual functions of cheap parts |
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|
"Henry Kiefer" <otc_friend@gmx.net> wrote in message
news:4385b3b1$1$27887$9b4e6d93@newsread4.arcor-online.net...
| Quote: | 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. |
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John Devereux
Guest
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| Posted:
Fri Nov 25, 2005 4:08 pm Post subject:
Re: Unusual functions of cheap parts |
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ehsjr <ehsjr@bellatlantic.net> writes:
| Quote: | 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 |
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Guest
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| Posted:
Fri Nov 25, 2005 5:35 pm Post subject:
Re: Unusual functions of cheap parts |
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|
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. |
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RST Engineering
Guest
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| Posted:
Fri Nov 25, 2005 5:35 pm Post subject:
Re: Unusual functions of cheap parts |
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And by varying the reverse bias through a current source (or moderately
large fixed resistor) you can make them into nifty phase shifters.
Jim
| Quote: | 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
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Jorgen Lund-Nielsen
Guest
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| Posted:
Fri Nov 25, 2005 5:35 pm Post subject:
Re: Unusual functions of cheap parts |
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John Larkin wrote:
| Quote: | On Thu, 24 Nov 2005 18:30:06 +0100, Jorgen Lund-Nielsen
jorgen.lund-nielsen@xxxxxxxxxxxxdesy.de> 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 |
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Jorgen Lund-Nielsen
Guest
|
| Posted:
Fri Nov 25, 2005 5:35 pm Post subject:
Re: Unusual functions of cheap parts |
|
|
Ban wrote:
| Quote: | 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 |
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Frithiof Andreas Jensen
Guest
|
| Posted:
Fri Nov 25, 2005 11:55 pm Post subject:
Re: Unusual functions of cheap parts |
|
|
"Henry Kiefer" <otc_friend@gmx.net> skrev i en meddelelse
news:4385b3b1$1$27887$9b4e6d93@newsread4.arcor-online.net...
| Quote: | 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. |
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John Larkin
Guest
|
| Posted:
Sat Nov 26, 2005 12:04 am Post subject:
Re: Unusual functions of cheap parts |
|
|
On Fri, 25 Nov 2005 12:46:17 +0100, Jorgen Lund-Nielsen
<jorgen.lund-nielsen@xxxxxxxxxxxxdesy.de> wrote:
| Quote: | John Larkin wrote:
On Thu, 24 Nov 2005 18:30:06 +0100, Jorgen Lund-Nielsen
jorgen.lund-nielsen@xxxxxxxxxxxxdesy.de> 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!
OK, I'll try some.
Thanks
John |
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John Larkin
Guest
|
| Posted:
Sat Nov 26, 2005 12:05 am Post subject:
Re: Unusual functions of cheap parts |
|
|
On Fri, 25 Nov 2005 09:07:38 +0000, Pooh Bear
<rabbitsfriendsandrelations@hotmail.com> wrote:
| Quote: |
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 |
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Paul Keinanen
Guest
|
| Posted:
Sat Nov 26, 2005 12:18 am Post subject:
Re: Unusual functions of cheap parts |
|
|
On Thu, 24 Nov 2005 18:49:24 -0500, Jon Yaeger <jono_1@bellsouth.net>
wrote:
| Quote: | 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 :-).
| Quote: | 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 |
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