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From: N_Cook on 18 Jun 2010 07:56
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 ?.
Resistors that fail open circuit if a designed-in current capacity weak
point is exceeded , fuse-fashion, not just the thermal limit of the body ,
so often no overheating discolouration to the body or surrounding board


From: Ron on 18 Jun 2010 08:15
On 18/06/2010 12:56, 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 ?.
> Resistors that fail open circuit if a designed-in current capacity weak
> point is exceeded , fuse-fashion, not just the thermal limit of the body ,
> so often no overheating discolouration to the body or surrounding board
>
>
The first ones I remember were in the dropper series on old televisions,
they had a spring (like half a safety pin) soldered to the terminals. Do
they count?
From: Phil Allison on 18 Jun 2010 08:30

"N_Cook"
>
> 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 ?.
> Resistors that fail open circuit if a designed-in current capacity weak
> point is exceeded , fuse-fashion, not just the thermal limit of the body ,
> so often no overheating discolouration to the body or surrounding board
>

** Genuine "fusible "resistors with specific fuse current ratings are rare
beasts - the only ones I know of were used by Yamaha in some of their 70s
and 80s audio amplifiers and were all miniature wire wound types.

OTOH - what are nowadays laughingly referred to as "fusible resistors" are
simply "flame proof" resistors - typically ordinary 0.5W & 1W metal film
types with a high temp, flame proof coating in lieu of the incendiary paint
coatings normally used.




..... Phil


From: Gerard Bok on 18 Jun 2010 08:30
On Fri, 18 Jun 2010 12:56:09 +0100, "N_Cook" <diverse(a)tcp.co.uk>
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
From: Michael A. Terrell on 18 Jun 2010 10:22

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 ?.
> Resistors that fail open circuit if a designed-in current capacity weak
> point is exceeded , fuse-fashion, not just the thermal limit of the body ,
> so often no overheating discolouration to the body or surrounding board


Fusible resistors have been common in the US for a very long time.
They were used in the early solid state car radios to prevent damage
when the germanium output transistors shorted. Probably started in car
radios about 1959. They were used in place of a fuse in a lot of early
line powered consumer electronics to prevent some idiot from bypassing a
blown fuse.


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
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