Hi,

thanks for the warnings. As always, I've taken a short cut (lack of 
time).  I also had to get the desk lamp out by today as my family return 
tomorrow and will want the desk lamp back(!) and wouldn't want a mains 
lead stretching across the garden/back yard.  It was nice and cosy 
inside the box when I opened it up, so the thermal insulation isn't too 
bad.  It was around 0C outside at the time.

I ripped out the flasher, stop and tail light string from our old Honda 
and attached that to the inside ceiling of the enclosure.  I'm only 
sending 5 volts dc to them (down 30m of mains lead) so they don't get 
very hot at all, just a warming glow.  Unfortunately I won't have much 
more time until the summer.  So I'll have to wait until then before 
changing over to resistors.  Unless of course it starts going bump in 
the night!

Cheers

Ian

ChrisAtUpw@....... wrote:

> In a message dated 08/01/2006, ian@........... writes:
>
>     I've spent the afternoon replacing the desk lamp in the enclosure
>     with 3
>     car lights. I'm starting off by feeding them 5 volts from an old PC
>     power supply. If that isn't warm enough then I'll switch to 12
>     volts. 
>
> Hi Ian,
>  
>     There are two problems with using light bulbs. You need to run 
> them at 3/4 the rated voltage to get a very long life from them and 
> the glass envelopes need to be kept cool. If the glass gets too hot, 
> oxygen may diffuse through it and shorten the filament life. The other 
> problem is that insects, spiders and small animals are attracted to a 
> warmed environment, particularly if it is also illuminated.     
>     Power resistors with an Al case which can be bolted onto an 
> earthed Al top plate in the enclosure and provided with soldered 
> connections are likely to give the most satisfactory permanent 
> solution. Farnell and RS sell them.   
>  
>     Regards,
>  
>     Chris Chapman




  
  


Hi,



thanks for the warnings. As always, I've taken a short cut (lack of
time).  I also had to get the desk lamp out by today as my family
return tomorrow and will want the desk lamp back(!) and wouldn't want a
mains lead stretching across the garden/back yard.  It was nice and
cosy inside the box when I opened it up, so the thermal insulation
isn't too bad.  It was around 0C outside at the time.



I ripped out the flasher, stop and tail light string from our old Honda
and attached that to the inside ceiling of the enclosure.  I'm only
sending 5 volts dc to them (down 30m of mains lead) so they don't get
very hot at all, just a warming glow.  Unfortunately I won't have much
more time until the summer.  So I'll have to wait until then before
changing over to resistors.  Unless of course it starts going bump in
the night!



Cheers



Ian



ChrisAtUpw@....... wrote:


  
  
  
  

  
In a message dated 08/01/2006, ian@........... writes:
  
I've spent the afternoon replacing the desk lamp in the
enclosure with 3 

car lights. I'm starting off by feeding them 5 volts from an old PC 

power supply. If that isn't warm enough then I'll switch to 12 volts.  

    
  
  
Hi Ian,
  
 
  
    There are two problems with using light bulbs. You need to
run them at 3/4 the rated voltage to get a very long life from them and
the glass envelopes need to be kept cool. If the glass gets too hot,
oxygen may diffuse through it and shorten the filament life. The other
problem is that insects, spiders and small animals are attracted to a
warmed environment, particularly if it is also illuminated.     
  
    Power resistors with an Al case which can be bolted onto an
earthed Al top plate in the enclosure and provided with soldered
connections are likely to give the most satisfactory permanent
solution. Farnell and RS sell them.   
  
 
  
    Regards,
  
 
  
    Chris Chapman