"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.

There even exists LED specially taylored to the needs of doing duplex
operation.

- Henry


"Frithiof Andreas Jensen"
schrieb im Newsbeitrag ...

"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.

On Fri, 25 Nov 2005 10:52:26 +0100, "Frithiof Andreas Jensen"
wrote:


"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.


And optocouplers can do interesting things:

Very simple high-voltage opamp, up to 400 volts p-p.

Isolated totem-pole driver, from a few volts up to 400.

Current limiter.

Low-leakage diode, sort of like an LED painted black.

John

Can you give details?

- Henry


"John Larkin" schrieb im
Newsbeitrag ...
On Fri, 25 Nov 2005 10:52:26 +0100, "Frithiof Andreas Jensen"
wrote:


"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.


And optocouplers can do interesting things:

Very simple high-voltage opamp, up to 400 volts p-p.

Isolated totem-pole driver, from a few volts up to 400.

Current limiter.

Low-leakage diode, sort of like an LED painted black.

John

On Sun, 27 Nov 2005 00:54:27 +0100, "Henry Kiefer"
wrote:

Can you give details?

- Henry


"John Larkin" schrieb im
Newsbeitrag ...
On Fri, 25 Nov 2005 10:52:26 +0100, "Frithiof Andreas Jensen"
wrote:


"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.


And optocouplers can do interesting things:

Very simple high-voltage opamp, up to 400 volts p-p.

Isolated totem-pole driver, from a few volts up to 400.

Current limiter.

Low-leakage diode, sort of like an LED painted black.

John



I posted some opamp schematics to abse a while back. I guess I could
do it again if they're no longer available.

The others chould be fairly obvious.

John

On Sat, 26 Nov 2005 15:41:27 -0800, John Larkin
wrote:

On Fri, 25 Nov 2005 10:52:26 +0100, "Frithiof Andreas Jensen"
wrote:


"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.


And optocouplers can do interesting things:

Very simple high-voltage opamp, up to 400 volts p-p.

Isolated totem-pole driver, from a few volts up to 400.

Current limiter.

Low-leakage diode, sort of like an LED painted black.

John

A latch.

--

Boris Mohar

On Sat, 26 Nov 2005 21:40:53 -0500, Boris Mohar
wrote:

On Sat, 26 Nov 2005 15:41:27 -0800, John Larkin
wrote:

On Fri, 25 Nov 2005 10:52:26 +0100, "Frithiof Andreas Jensen"
wrote:


"Henry Kiefer" wrote in message
r-online.net...

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

LED's work both ways, as a light emitter and a photodiode.


And optocouplers can do interesting things:

Very simple high-voltage opamp, up to 400 volts p-p.

Isolated totem-pole driver, from a few volts up to 400.

Current limiter.

Low-leakage diode, sort of like an LED painted black.

John

A latch.


Right, if CTR 1.

John

(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

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

A simple 1.0 K Ohm or so carbon film resistor placed across the
line makes a very nice display after a couple of seconds. They also
make a handy fuse to trigger a little firecracker when used as a
"surprise" for some unsuspecting technician placed across his load
behind the workbench when he turns it on in the morning.

boB
K7IQ