Why not use dimmer with light flashing device?

[JS]

This device which you insert between the lampholder and bulb,
switches the bulb on & off at random when it gets dark.

http://www.timeguard.com/details.php?product=34

I guess the device must contain some basic electronics.

------------

The full instructions says not to use this in a circuit which
contains a dimmer but why is this?

(1) Would the problem be that the dimmer and/or this device get
damaged?

(2) Alternatively, would the problem be simply be that the unit does
not function properly when the voltage (er, current?) is reduced by
the dimmer.

 

[Victor Roberts]

On Sat, 03 Dec 2005 00:57:10 GMT, JS
<j_simmonmds@nomailthankyou.com> wrote:

This device which you insert between the lampholder and bulb,
switches the bulb on & off at random when it gets dark.

http://www.timeguard.com/details.php?product=34

I guess the device must contain some basic electronics.

------------

The full instructions says not to use this in a circuit which
contains a dimmer but why is this?

(1) Would the problem be that the dimmer and/or this device get
damaged?

(2) Alternatively, would the problem be simply be that the unit does
not function properly when the voltage (er, current?) is reduced by
the dimmer.

2 for certain and probably also 1.

--
Vic Roberts
http://www.RobertsResearchInc.com
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[Palindr☝me]

JS wrote:

This device which you insert between the lampholder and bulb,
switches the bulb on & off at random when it gets dark.

http://www.timeguard.com/details.php?product=34

I guess the device must contain some basic electronics.

------------

The full instructions says not to use this in a circuit which
contains a dimmer but why is this?

(1) Would the problem be that the dimmer and/or this device get
damaged?

(2) Alternatively, would the problem be simply be that the unit does
not function properly when the voltage (er, current?) is reduced by
the dimmer.

A dimmer basically chops out bigger and bigger pieces of
the mains sine wave input as it is turned down. Eventually
there is hardly anything of the sine wave left to power
either a lamp, or this unit.

Apart from anything else, the very simple means *normally*
used inside the unit to reduce mains voltage to the low
voltage needed for the unit's electronics won't produce
enough output to be reliable at lower dimmer setting.

I would be surprised if a simple dimmer were damaged by this.

The unit probably won't get damaged either but would simply
not work at all or be very unreliable at different dimmer
settings. But it is not using it as the designer intended,
so, it could.

Operating this unit with a circuit fitted with a simple (eg
rotary knob type) dimmer would probably be fine, if the
dimmer was always set to maximum, or very near maximum.

However, using it with a more advanced dimmer (e.g.
soft-start, remote control, etc) could easily cause
problems. These typically don't allow you to set the output
to maximum at all times.

However, it is never a good idea to operate anything other
than in accordance with the manufacturer's recommendations.
This is particularly a bad idea when having to make
assumptions about the design - as in this case.

--
Sue

 

[Ian Stirling]

In sci.engr.lighting JS <j_simmonmds@nomailthankyou.com> wrote:

This device which you insert between the lampholder and bulb,
switches the bulb on & off at random when it gets dark.

http://www.timeguard.com/details.php?product=34

I guess the device must contain some basic electronics.
snip
(2) Alternatively, would the problem be simply be that the unit does
not function properly when the voltage (er, current?) is reduced by
the dimmer.

Basically yes - and that it might not let the dimmer function even when
set to 'full'.
It's not very likely to cause actual damage - though not totally impossible.

 

JS wrote:

This device which you insert between the lampholder and bulb,
switches the bulb on & off at random when it gets dark.

http://www.timeguard.com/details.php?product=34

I guess the device must contain some basic electronics.

------------

The full instructions says not to use this in a circuit which
contains a dimmer but why is this?

(1) Would the problem be that the dimmer and/or this device get
damaged?

(2) Alternatively, would the problem be simply be that the unit does
not function properly when the voltage (er, current?) is reduced by
the dimmer.

I'm wondering why you'd want to. Its a strange fashion to use a dimmed
100w bulb @ 90w when you want a 40. If youve got one central room light
only, and dont want to waste as much power when out, 2 things come to
mind:
1. dimmers wont save much, as they drop efficiency fairly quickly
2. a separate plug in light and the right bulb would be cheaper in run
cost


NT

 

[Palindr☝me]

meow2222@care2.com wrote:

JS wrote:

This device which you insert between the lampholder and bulb,
switches the bulb on & off at random when it gets dark.

http://www.timeguard.com/details.php?product=34

I guess the device must contain some basic electronics.

------------

The full instructions says not to use this in a circuit which
contains a dimmer but why is this?

(1) Would the problem be that the dimmer and/or this device get
damaged?

(2) Alternatively, would the problem be simply be that the unit does
not function properly when the voltage (er, current?) is reduced by
the dimmer.


I'm wondering why you'd want to. Its a strange fashion to use a dimmed
100w bulb @ 90w when you want a 40. If youve got one central room light
only, and dont want to waste as much power when out, 2 things come to
mind:
1. dimmers wont save much, as they drop efficiency fairly quickly
2. a separate plug in light and the right bulb would be cheaper in run
cost

I would imagine that where this would arise is when the dimmer is

already built into the wall swtich. The random on/off unit is meant to
be plugged into a normal light socket to make the room/house appear
occupied - so a householder could wish to put it in a ceiling fitting
supplied via a dimmer switch on the wall.


--
Sue

 

[Clive Mitchell]

In message <439bec6d$0$18557$ed2619ec@ptn-nntp-reader02.plus.net>, Ian
Stirling <root@mauve.demon.co.uk> writes

Basically yes - and that it might not let the dimmer function even when
set to 'full'. It's not very likely to cause actual damage - though not
totally impossible.

Given that many of the simple lighting control circuits use a capacitive
dropper to derive the low voltage supply for the control circuitry, I
guess that the worst case scenario is going to be at half intensity
where the dimmer is switching repeatedly on the peak mains voltage.
Each time it did this would cause a high inrush to the capacitor and
could damage the inline surge limiting resistor.

--
Clive Mitchell
http:/www.bigclive.com