"My Dimmers fail and fail, why?"

I'd been destroying dimmers on a handful. I'd been making homemade dimmer
control (from ordinary residential dimmers) for my reading lamp. (Don't know if
this violates safety codes.) I would plug the dimmer to the wall receptacle
outlet and then plug the lamp into the dimmer. It's a handy device I carry
around the house to any reading corner.
But the problem is that sometime while plugging the dimmer into the
wall (with the lamp turned on) the dimmer tends for fail (or turn on at full).
The dimmer is then discarded. The dimmer's death come at the same time as I
noticed an arch inside the wall outlet while attempting to plug it in. It's
probably not design for this since an aftermarket lamp dimmer I also have won't
fail in any abusive condition. My homemade dimmers have a problem I have no
solutions for and like to solve it. Any suggestions?

Why am I making homade lamp dimmers? A friend gave me a shoe-box half full of
used dimmers.
-w orchid

[This followup was posted to sci.electronics.repair and a copy was sent to
the cited author.]

In article <(E-Mail Removed)>,
(E-Mail Removed) says...
> I'd been destroying dimmers on a handful. I'd been making homemade dimmer
> control (from ordinary residential dimmers) for my reading lamp. (Don't know if
> this violates safety codes.) I would plug the dimmer to the wall receptacle
> outlet and then plug the lamp into the dimmer. It's a handy device I carry
> around the house to any reading corner.
> But the problem is that sometime while plugging the dimmer into the
> wall (with the lamp turned on) the dimmer tends for fail (or turn on at full).
> The dimmer is then discarded. The dimmer's death come at the same time as I
> noticed an arch inside the wall outlet while attempting to plug it in. It's
> probably not design for this since an aftermarket lamp dimmer I also have won't
> fail in any abusive condition. My homemade dimmers have a problem I have no
> solutions for and like to solve it. Any suggestions?
>
> Why am I making homade lamp dimmers? A friend gave me a shoe-box half full of
> used dimmers.

How many watts is the reading lamp? Is it a plain incandescent bulb,
halogen, or something else?

Why leave the light on when plugging in the dimmer? Turn it OFF first,
plug things in, then turn on the light.

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It's a plain100W incandescent bulb. Sometimes somebody would leave the lamp on
accidently.
-W

> How many watts is the reading lamp? Is it a plain incandescent bulb,
>halogen, or something else?
>
> Why leave the light on when plugging in the dimmer? Turn it OFF first,
>plug things in, then turn on the light.
>
>--

>> I'd been destroying dimmers on a handful. I'd been making homemade dimmer
>> control (from ordinary residential dimmers) for my reading lamp. (Don't
>know if
>> this violates safety codes.) I would plug the dimmer to the wall receptacle
>> outlet and then plug the lamp into the dimmer. It's a handy device I carry
>> around the house to any reading corner.
>> But the problem is that sometime while plugging the dimmer into
>the
>> wall (with the lamp turned on) the dimmer tends for fail (or turn on at
>full).
>> The dimmer is then discarded. The dimmer's death come at the same time as I
>> noticed an arch inside the wall outlet while attempting to plug it in. It's
>> probably not design for this since an aftermarket lamp dimmer I also have
>won't
>> fail in any abusive condition. My homemade dimmers have a problem I have no
>> solutions for and like to solve it. Any suggestions?
>>
>> Why am I making homade lamp dimmers? A friend gave me a shoe-box half full
>of
>> used dimmers.

Dimmer circuits, as simple as they look, the design and part values can
be a bit critical. But, if your dimmer circuit is actually okay, then
you have to investigate the load.

Some of these reading lamps use a small transformer inside. This is to
step the mains voltage down for a small type of reading bulb.

You cannot run a transformer or reactive device on a simple thyristor
dimmer. If so, the transformer may either burn out the dimmer, or be
damaged. This has to do with a number of complex reasons which is
really beyond what I can get in to over an email.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
==============================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
Instruments http://www.zoom-one.com/glgtech.htm
==============================================
"Wdyorchid" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
I'd been destroying dimmers on a handful. I'd been making homemade
dimmer
control (from ordinary residential dimmers) for my reading lamp. (Don't
know if
this violates safety codes.) I would plug the dimmer to the wall
receptacle
outlet and then plug the lamp into the dimmer. It's a handy device I
carry
around the house to any reading corner.
But the problem is that sometime while plugging the dimmer
into the
wall (with the lamp turned on) the dimmer tends for fail (or turn on at
full).
The dimmer is then discarded. The dimmer's death come at the same time
as I
noticed an arch inside the wall outlet while attempting to plug it in.
It's
probably not design for this since an aftermarket lamp dimmer I also
have won't
fail in any abusive condition. My homemade dimmers have a problem I have
no
solutions for and like to solve it. Any suggestions?

Why am I making homade lamp dimmers? A friend gave me a shoe-box half
full of
used dimmers.
-w orchid

Indescant bulbs use to die at power on due to the current peak that occurs
as the cold filament has much lower a resistance then a hot one. The triac
of a dimmer may be killed by the same current peak, especially when its
maximum peak current is too low and/or the control circuit has not been
developped to handle the triac with (full) load at power on. The arch you
noticed points in that direction. I would (like) to reverse engineer both
the failing and the aftermarket dimmer. I'm sure the difference will explain
the cause of the failure.

pieter



"Wdyorchid" <(E-Mail Removed)> schreef in bericht
news:(E-Mail Removed)...
> It's a plain100W incandescent bulb. Sometimes somebody would leave the
lamp on
> accidently.
> -W
>
> > How many watts is the reading lamp? Is it a plain incandescent bulb,
> >halogen, or something else?
> >
> > Why leave the light on when plugging in the dimmer? Turn it OFF first,
> >plug things in, then turn on the light.
> >
> >--
>
> >> I'd been destroying dimmers on a handful. I'd been making homemade
dimmer
> >> control (from ordinary residential dimmers) for my reading lamp. (Don't
> >know if
> >> this violates safety codes.) I would plug the dimmer to the wall
receptacle
> >> outlet and then plug the lamp into the dimmer. It's a handy device I
carry
> >> around the house to any reading corner.
> >> But the problem is that sometime while plugging the dimmer
into
> >the
> >> wall (with the lamp turned on) the dimmer tends for fail (or turn on at
> >full).
> >> The dimmer is then discarded. The dimmer's death come at the same time
as I
> >> noticed an arch inside the wall outlet while attempting to plug it in.
It's
> >> probably not design for this since an aftermarket lamp dimmer I also
have
> >won't
> >> fail in any abusive condition. My homemade dimmers have a problem I
have no
> >> solutions for and like to solve it. Any suggestions?
> >>
> >> Why am I making homade lamp dimmers? A friend gave me a shoe-box half
full
> >of
> >> used dimmers.
>
>


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Incandescent lamps can have an inrush current that is 10 times normal
due to the cold filament. Always start dimmers in the low position
which allows the filament to gradually reach operating temp.

Grumpy

"Jerry G." <(E-Mail Removed)> wrote in message news:<bi9cma$i2h$(E-Mail Removed)>...
> Dimmer circuits, as simple as they look, the design and part values can
> be a bit critical. But, if your dimmer circuit is actually okay, then
> you have to investigate the load.
>
> Some of these reading lamps use a small transformer inside. This is to
> step the mains voltage down for a small type of reading bulb.
>
> You cannot run a transformer or reactive device on a simple thyristor
> dimmer. If so, the transformer may either burn out the dimmer, or be
> damaged. This has to do with a number of complex reasons which is
> really beyond what I can get in to over an email.
>
> --
>
> Greetings,
>
> Jerry Greenberg GLG Technologies GLG
> ==============================================
> WebPage http://www.zoom-one.com
> Electronics http://www.zoom-one.com/electron.htm
> Instruments http://www.zoom-one.com/glgtech.htm
> ==============================================
> "Wdyorchid" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
> I'd been destroying dimmers on a handful. I'd been making homemade
> dimmer
> control (from ordinary residential dimmers) for my reading lamp. (Don't
> know if
> this violates safety codes.) I would plug the dimmer to the wall
> receptacle
> outlet and then plug the lamp into the dimmer. It's a handy device I
> carry
> around the house to any reading corner.
> But the problem is that sometime while plugging the dimmer
> into the
> wall (with the lamp turned on) the dimmer tends for fail (or turn on at
> full).
> The dimmer is then discarded. The dimmer's death come at the same time
> as I
> noticed an arch inside the wall outlet while attempting to plug it in.
> It's
> probably not design for this since an aftermarket lamp dimmer I also
> have won't
> fail in any abusive condition. My homemade dimmers have a problem I have
> no
> solutions for and like to solve it. Any suggestions?
>
> Why am I making homade lamp dimmers? A friend gave me a shoe-box half
> full of
> used dimmers.
> -w orchid


My guess is that with a 100 watt incandescent bulb, the initial inrush
current is causing the problem. The bulb has a very low cold
resistance, and there is a surge of curent for the first few cycles
until the filament heats up. This surge may be the problem. Think of
how most incandescent lights fail, they fail with a flash when they
are first turned on. Very few fail while they are in the steady-state
on mode. The inrush curent problem is why most dimmers say to turn
the dimmer to the off position while installing the dimmer.

H. R. (Bob) Hofmann

(E-Mail Removed) (Grumpy OM) writes:

> Incandescent lamps can have an inrush current that is 10 times normal
> due to the cold filament. Always start dimmers in the low position
> which allows the filament to gradually reach operating temp.

Yes, but normal dimmers don't die when switched on at full brightness.

When light bulbs die, the instantaneous current can be much higher.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
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(E-Mail Removed) (H. R. Bob Hofmann) writes:

> "Jerry G." <(E-Mail Removed)> wrote in message news:<bi9cma$i2h$(E-Mail Removed)>...
> > Dimmer circuits, as simple as they look, the design and part values can
> > be a bit critical. But, if your dimmer circuit is actually okay, then
> > you have to investigate the load.
> >
> > Some of these reading lamps use a small transformer inside. This is to
> > step the mains voltage down for a small type of reading bulb.
> >
> > You cannot run a transformer or reactive device on a simple thyristor
> > dimmer. If so, the transformer may either burn out the dimmer, or be
> > damaged. This has to do with a number of complex reasons which is
> > really beyond what I can get in to over an email.
> >
> > --
> >
> > Greetings,
> >
> > Jerry Greenberg GLG Technologies GLG
> > ==============================================
> > WebPage http://www.zoom-one.com
> > Electronics http://www.zoom-one.com/electron.htm
> > Instruments http://www.zoom-one.com/glgtech.htm
> > ==============================================
> > "Wdyorchid" <(E-Mail Removed)> wrote in message
> > news:(E-Mail Removed)...
> > I'd been destroying dimmers on a handful. I'd been making homemade
> > dimmer
> > control (from ordinary residential dimmers) for my reading lamp. (Don't
> > know if
> > this violates safety codes.) I would plug the dimmer to the wall
> > receptacle
> > outlet and then plug the lamp into the dimmer. It's a handy device I
> > carry
> > around the house to any reading corner.
> > But the problem is that sometime while plugging the dimmer
> > into the
> > wall (with the lamp turned on) the dimmer tends for fail (or turn on at
> > full).
> > The dimmer is then discarded. The dimmer's death come at the same time
> > as I
> > noticed an arch inside the wall outlet while attempting to plug it in.
> > It's
> > probably not design for this since an aftermarket lamp dimmer I also
> > have won't
> > fail in any abusive condition. My homemade dimmers have a problem I have
> > no
> > solutions for and like to solve it. Any suggestions?
> >
> > Why am I making homade lamp dimmers? A friend gave me a shoe-box half
> > full of
> > used dimmers.
> > -w orchid
>
>
> My guess is that with a 100 watt incandescent bulb, the initial inrush
> current is causing the problem. The bulb has a very low cold
> resistance, and there is a surge of curent for the first few cycles
> until the filament heats up. This surge may be the problem. Think of
> how most incandescent lights fail, they fail with a flash when they
> are first turned on. Very few fail while they are in the steady-state
> on mode. The inrush curent problem is why most dimmers say to turn
> the dimmer to the off position while installing the dimmer.
> H. R. (Bob) Hofmann

Push-on, push-off dimmers do not die if switched on at full brightness!

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Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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Important: The email address in this message header may no longer work. To
contact me, please use the Feedback Form at repairfaq.org. Thanks.

When they fail; do they fail such that they are at full brightness or no
light at all?

Wdyorchid wrote:
> I'd been destroying dimmers on a handful. I'd been making homemade dimmer
> control (from ordinary residential dimmers) for my reading lamp. (Don't know if
> this violates safety codes.) I would plug the dimmer to the wall receptacle
> outlet and then plug the lamp into the dimmer. It's a handy device I carry
> around the house to any reading corner.
> But the problem is that sometime while plugging the dimmer into the
> wall (with the lamp turned on) the dimmer tends for fail (or turn on at full).
> The dimmer is then discarded. The dimmer's death come at the same time as I
> noticed an arch inside the wall outlet while attempting to plug it in. It's
> probably not design for this since an aftermarket lamp dimmer I also have won't
> fail in any abusive condition. My homemade dimmers have a problem I have no
> solutions for and like to solve it. Any suggestions?
>
> Why am I making homade lamp dimmers? A friend gave me a shoe-box half full of
> used dimmers.
> -w orchid
>