"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