Isaac Marino Bavaresco wrote:
> Perhaps not a good idea for the present circuit. The bulbs would be
> subjected to a little thermal ripple.

Thermal ripple isn't actually a big deal to a incandescent fillament.  It
does make it move a little, but it's designed with strain reliefs to allow
for that.  What kills fillaments is high temperature, which causes the
fillament to essentially evaporate.  This effect is greatly (very
non-linear) reduced as the temperature goes down.

Think of all the incandescent bulbs you have seen used as blinkers or
frequency switched on and off.  How long did bulbs last in blinking yellow
traffic lights, for example?  Some of these were on 24/7, probably for
years.  I doubt this lunch heater is going to see anywhere near that number
of on/off cycles over its life.  Then even if the bulbs go out once a year,
they're cheap.

> I think it would be better to use a TRIAC and control the conduction
> angle or at least skip some half-cycles. It would be less noisy also.

This takes more control and electronics knowledge, something we're not sure
yet is available.


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