On Jun 18, 7:35*am, "N_Cook" wrote:
Gerard Bok wrote in message

...





On Fri, 18 Jun 2010 12:56:09 +0100, "N_Cook"
wrote:

When did they first arrive and do they always have an unusual body
colour?
There is a patent reference to 1977 but when would the first appearance
in
domestic equipment have been ?.

Way before 1977 !

Take a look at radio and TV sets from the late 50s and 60s.
Big white or beige wirewound resistors in a ceramic housing, one
of the leads spring loaded along the edge, low temp solder blob
on the spring to keep the circuit closed.

Designed to cut open when the resistor's body reaches some 200
degrees *Celsius / 400 degrees Fahrenheit.

(I think I can digg up a picture, if you want :-)

--
Kind regards,
Gerard Bok

Sorry, I should have said fusible resistors otherwise visually
indistinguishable from conventional 1/3 or 1/2W, MO resistors.
Grey bodied 1/3W and 1/2W Philips ones in a 1992 Farnell catalogue- Hide quoted text -

- Show quoted text -

Don't know about that exact type, but we were using a black coated 5W
axial WW from, I think, Dale and it looked exactly like the normal 5W
axial except the usual number ended in "F". It, presumably, used a
weak point since it fused on overcurrent rather than overheating. That
was back in the early '90s. As mentioned by others, the 'sand coated'
"Fusistors" have been around at least since WWII.

Neil S.