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.

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

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

"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.

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

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

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

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

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

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