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

"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.

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

A metal case of a crystal should never soldered!! This may break the
oscillation characteristics. At least you must know what you're doing here.
This type of built-in failure mode is often seen in products.
Otherwise it is interesting!

Another error with crystals is to ultrasonic the populated pcb. With the
right sonic frequency the crystals comes in resonance - cracking of parts or
wires!

- Henry


"RST Engineering" schrieb im Newsbeitrag
...
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

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

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.

Am Sat, 26 Nov 2005 16:16:27 +0000 (UTC) schrieb Matthias Weingart
:

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.

But how to decide to switch it off? I think there you have to sample -
switch of for a short time and test. This could give a flickering
backlight.

--
Martin

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

But how to decide to switch it off? I think there you have to
sample - switch of for a short time and test. This could give a
flickering backlight.

Ok, you found the skeleton in the closet. :-) You can not use
this method to switch it off - but it is not required in most cases.
Think of a cell phone - the backlight goes on every time you press a
key, and it is going off after 10 seconds.

M.
--
Bitte auf antworten.

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" 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

In article ,
Henry Kiefer wrote:
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.

It also works for this:
Vcc
!/c
--/\/\/\---+------!
! !\e
V !
--- ----/\/\/--+--- too load
! !
--------------------

You get a current limit and an indicator light.


--
--
forging knowledge