=?iso-8859-1?B?U2XhbiBPJ0xlYXRobPNiaGFpcg==?= writes:

Se=E1n O'Leathl=F3bhair wrote:
I am not sure if this is an appropriate group for this question. If
not, please suggest a better one.

I have a light in the house which I have wanted to switch to a low
energy bulb for a long time. The hold up was that I needed a very
small bulb. At last, I have found a small enough bulb but something
odd occurred as soon as I put it in.

When it is switched on, it works as expected.

When it is switched off, it blinks every few seconds. So, I guess
that there must be a problem with the switch If it is passing nothing
then it would seem impossible for the bulb to do anything. I did not
notice any problem with the previous incandescent bulb but I guess
that if the switch is leaking a tiny amount, the filament would glow
too little to be seen.

I have a few questions:

What is going on? Is a tiny current leaking, building up a charge in
a capacitor somewhere until a sufficient voltage builds up to spark in
the bulb and discharge the capacitor, and then the cycle repeats.

Is it safe?

Will it wear out the bulb very fast?

Is it likely to be enough to replace the switch? (Actually three
switches can turn this bulb on and off).

Might I have to replace the wiring? (Much harder than just replacing
the switches)

So many replies that it is hard to know which one to reply to so I
will reply here.

A curious feature that I forgot to mention is the regularlity of the
flashes: every 2 seconds with no variation that I can detect with a
stop watch. This is why I thought of a capacitor charging up until it
reaches a critical voltage. But I was thinking of DC. AC is not going
to charge up a capacitor over 2 seconds. What is inside these bulbs? A
rectifier? A capacitor?

No, you're correct. See my (and other) replies. It is a capacitor
charging up - after a rectifier.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

I will do some checking at the weekend. Climb into the loft space for
a look. Get the multimeter out. Trying other low energy bulbs. Try the
higher rated bulb. Etc.