How to dim light without using a dimmer

[THRIPSTER]

What about a 'variable' mechanical screen in front of the lamp (located at a safe distance)?

Regards

 

[Hager]

Unless the Hi-Fi equipment you are using is quite old or relativity cheap you shouldn't need it.

I've used both cheap and expensive amps in dimmer rooms with around 50/60 loaded dimmer channels, the cheaper amps allowed a lot of interference in but the more higher end ones made a difference, with the channels varying from 35-65% and the gain on both mixer, processing and amps full all that could be heard was hiss from what the amps themselves made.

The quality of the earth also makes a difference, if its not clean it will allow a fair amount of buzzing, the cable quality also helps quite a bit but just don't run them next to mains cables.

Adjust the gain on the amp it can also have an effect but thats more of hiss from HF drivers.

Even with my amps at home where i have a dimmer rack on top of a low end PA amp the effect is virtually none.

 

[Yukster]

Series connections of two identical lamps is a relatively simple way to dim a pair of lamps. They operate at approx 1/4 power and give a very warm glow

Can i check with you folks whether i got it right? Currently my lamp is connected in a parallel circuit. To dim it I should 1. isolate the circuit;
2. add another lamp in series by removing the live wire from the existing light socket and connecting it to the live terminal of the additional socket. I should then connect a neutral wire from the additional socket to the live terminal of the original light

 

[Yukster]

The auto transformer is really the only way not producing massive amount of heat and clearly will not fit in a standard switch back box

My light bulb is 40W. What auto transformer do I need to reduce brightness by 60%? I would appreciate if you can post a link to a good quality transformer that I could buy. It wont fit in the backbox so can I place the transformer in the ceiling cavity?

 

[winston1]

VA rating of the transformer must be at least twice that of the lamp.

Not so. The lamp at half voltage would take quarter power if filament resistance didn't change. It will of course so lamp will take a little more than quarter but less than half power. There is no need for the transformer VA rating to be more than half that of the lamp.

Let's say 40 watt lamp would take 166mA on 240V. On 120v let's say 100mA. When connected to the tap 50mA will flow from the 240V end and another 50mA from the 0V end which will add in the lamp. Total VA for transformer equals 240x50/1000=12.

 

[bernardgreen]

I cannot recall the equations.

The energy supplied to the lamp comes from half the winding. therefor that half has to be able to cope with the energy that it supplies to the lamp. In the case of a standard transformer the other half would be wound to the same specification so would have the same VA rating as the half supplying the lamp.

As there is no current flowing in the un-used secondaries the magnetic circuit is not as designed and eddy current heating may be higher than if the transformer is used as designed with the secondaries loaded.

 

[viewer]

What is above the ceiling from which the pendant drops? Is it possible to fit a well ventilated box above the ceiling? Easy in a bungalow, but feasible if a good clearance between ceiling and floor if this is a g/f room. Into the box fit a CLS 40W lamp and thence to the pendant in series. The ventilation would need to remove 20W + safety factor as heat.

 

[Yukster]

What is above the ceiling from which the pendant drops? Is it possible to fit a well ventilated box above the ceiling? Easy in a bungalow, but feasible if a good clearance between ceiling and floor if this is a g/f room. Into the box fit a CLS 40W lamp and thence to the pendant in series. The ventilation would need to remove 20W + safety factor as heat.

Thanks! what is a CLS lamp? I googled it but I'm still not sure which lamp i need.
The pendant drops from the ceiling of the ground floor hallway. Second floor is above it and the clearance is 8" or 9". How do i measure if ventilation is sufficient?

 

[winston1]

What I find amazing is that anyone one spend £21.60 on an inefficient incandescent light bulb.

 

[winston1]

I cannot recall the equations.

The energy supplied to the lamp comes from half the winding.

No, it is as I described. Half the energy for the lamp comes from the top winding and the other half from the bottom winding.

Using a transformer with the secondaries unloaded does not increase the eddie currents. Iron losses remain constant.

 

[Yukster]

What I find amazing is that anyone one spend £21.60 on an inefficient incandescent light bulb.

I got the light bulb for effect. I think it looks beutiful but it may not float your boat. Can't argue about taste, or can you?!

 

[ekmdgrf]

Don't forget to get yourself a decent plug for the stereo:

http://www.decoaudio.com/deco_audio_mains_plugs.html

Although I'd be inclined to ditch noisy mains altogether and run the thing off a car battery.

Be sure to get one of these too:

http://www.elusivedisc.com/AUDIOPRISM-CD-STOPLIGHT-PEN/productinfo/AP-CDSL/

 

[bernardgreen]

http://www.poormojo.org/pmjadaily/archives/009864.php

Silver Rock Signature Knob $480.00
>
> Good vibrations, Bad vibrations it?s all about vibrations!! RAM would like
> to introduce a new signature level knob developed for the mighty Silver
> Rock potentiometer. The standard bakelite knob is certainly the best
> sounding compromise... but now Audio Consulting has taken this aspect of
> the Silver Rock much further. The new knobs are custom made with beech
> wood and bronze where the bronze is used as the insert to mount to the
> stem of the volume pot. The beech wood is coated several times with C37
> lacquer for best sound as pointed out by Dieter Ennemoser. How can this
> make a difference??? Well, hearing is believing as we always say. The
> sound becomes much more open and free flowing with a nice improvement in
> resolution. Dynamics are better and overall naturalness is improved. Here
> is a test for all you Silver Rock owners. Try removing the bakelite knobs
> and listen. You will be shocked by this! The signature knobs will have an
> even greater effect?really amazing! The point here is the micro vibrations
> created by the volume pots and knobs find their way into the delicate
> signal path and cause degradation (Bad vibrations equal bad sound). With
> the signature knobs micro vibrations from the C37 concept of wood, bronze
> and the lacquer itself compensate for the volume pots and provide (Good
> Vibrations) our ear/brain combination like to hear?way better sound!!
>
> Knobs can easily be installed on all versions of the Silver Rock potentiometer.
>
>

I noted that on that website, a 0.5 ounce of "C37" lacquer sells for $60.

Here's the C37 "theory":

http://www.ennemoser.com/c37theory.html

Especially striking is the inventor's claim: "All attempts by science to
explain the secrets of the character of sound have so far been unsuccesful".

 

[Yukster]

So now that we all had a laugh, could you please help with my remaining questions?
1. If I connect a second light bulb in the 8” clearance between the first floor ceiling and the second floor, how to I effectively get rid of the 20W of heat
2. What auto transformer is suitable if I choose it as a way to dim the light?
Thanks

 

[flameport]

A second lamp is a poor solution, due to the wasted heat, and the fact that when the second lamp fails, the main one won't work either.

The transformer option is far better. For only one lamp, something like this:
http://www.ebay.co.uk/itm/290731681595
would be adequate.