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