[time-nuts] HP10811 losing EFC

[Magnus Danielson]

Rick,

Richard (Rick) Karlquist wrote:
> 
> 
> paul swed wrote:
>> Or simply fuse externally with a reasonable fuse holder and fuse.
> 
> No, you don't understand.  It is a THERMAL fuse.  It must be IN
> the oven to do any good.  There is definitely no excess room
> inside of the 10811 to add a fuse holder.

For a thermal fuse to make any use, it needs to be in the oven, but for 
pure over-current protection and external normal fuse will work, which 
is what he proposes. However, the trouble with dimensioning a normal 
fuse is that it needs to survive the heatup period, where as for a 
run-away oven the heatup never ends. The setability of the current limit 
of a fuse isn't particularly great so that it can be distinguished.

The only way to achieve any meaningfull protection will be a thermal 
fuse. Only very little additional protection is achieved by a normal fuse.

Cheers,
Magnus