Is it possible to have "full" and "dim" lightswitches?

[securespark]

I had a diagram in one of my old 15th Ed books about how to wire 2 lamps so you can have a dim/high setting.

Can I find the bugger?

 

[JohnW2]

I had a diagram in one of my old 15th Ed books about how to wire 2 lamps so you can have a dim/high setting. Can I find the bugger?

With two lamps/bulbs,it was actually possible to have them wired for three different light levels:

1...One lamp on
2...Both lamps on 'full' (wired in parallel)
3...Both lamps on 'dimmed' (wired in series)

... with the brightness of (1) normally being intermediate between (2) and (3).

However, that only works with incansdescent lamps/bulbs,so is of limited relevance thse days - so I won't both posting the wiring needed to achieve it

Kind Regards, John

 

[winston1]

With two lamps/bulbs,it was actually possible to have them wired for three different light levels:

1...One lamp on
2...Both lamps on 'full' (wired in parallel)
3...Both lamps on 'dimmed' (wired in series)

... with the brightness of (1) normally being intermediate between (2) and (3).

However, that only works with incansdescent lamps/bulbs,so is of limited relevance thse days - so I won't both posting the wiring needed to achieve it

Kind Regards, John

In the US twin filament lamps are available, say 40 and 60 watt. The ES bases have an additional contact ring so they can be switched 40, 60, or 100w. They are usually found in table lamps. I understand there is a CFL version these days.

 

[SUNRAY]

In the US twin filament lamps are available, say 40 and 60 watt. The ES bases have an additional contact ring so they can be switched 40, 60, or 100w. They are usually found in table lamps. I understand there is a CFL version these days.

That's also a European thing, A French couple fitted many accessories from home, they had a light over the dining table with a 15/80W IIRC and a 3 position switch on the wall, the 15W element failed while we were eating and the spare (for the lounge) was more like 40/80W.

I've also seen a B22 with 3 bayonet pins (very different spacing to the IR heat lamps) which used the metal case as the common for a normal/orange colour (not just running at a lower voltage) in the fairground.

 

[Harry Bloomfield]

The 12v light fitting in my caravan's bathroom rather oddly, was built with two lamps/three lighting levels - dim (in series), medium (one lamp), bright both lamps in parallel.

 

[bernardgreen]

Many of the lights in my cottage are wired in pairs to provide traditional warm glow dimming by connecting two in series. They are incandescent lamps.

A custom designed controller operates relays to switch the supply to the lamps

 

[JohnW2]

Many of the lights in my cottage are wired in pairs to provide traditional warm glow dimming by connecting two in series. They are incandescent lamps. A custom designed controller operates relays to switch the supply to the lamps

Given that some people are very risk-averse, and consider even the most improbable of possible faults/malfunctions ...

... Some may be concerned by the possibility that a 'controller malfunction' could, for example, result in the right-hand lamp being 'off', but "live" (i.e. "R1+R3" - which presumably is something which 'should never happen').

Kind Regards, John

 

[bernardgreen]

R1 + R3 is a non valid combination and should never happen, but then with software anything can happen.

 

[JohnW2]

R1 + R3 is a non valid combination and should never happen ...

Quite - as I wrote ...

... (i.e. "R1+R3" - which presumably is something which 'should never happen')

... but, as you go on to say

... but then with software anything can happen.

... which echoes my ...

Given that some people are very risk-averse, and consider even the most improbable of possible faults/malfunctions ...

... which is why I was surprised that you, of all people, would be comfortable with what you described

Kind Regards, John

 

[Harry Bloomfield]

... which is why I was surprised that you, of all people, would be comfortable with what you described

I presume you have heard of interlocking so that cannot happen?

 

[JohnW2]

I presume you have heard of interlocking so that cannot happen?

In nearly all contexts, "cannot happen" is a very dangerous concept to rely on However, steps can be taken to minimise risks, even if they aree already incredibly small.

From what he says, bernard is relying on "software interlocking" - which, as he admits, is not infallible. Mechanical interlocking would probably be theoretically 'safer', but the whole exercise would then start (if it hasn't already started!!) becoming rather (maybe 'inappropriately'?) complicated for the control of a couple of domestic lights

Given that he's talking about a system that will only work with incandescent lamps/bulbs, I did wonder why he did not just have a single lamp/bulb in series with a diode (to achieve 'dimmed'), with a switch (or relay contacts) across the diode to 'short' it for 'full brightness'.

Kind Regards, John

 

[bernardgreen]

not just have a single lamp/bulb in series with a diode (to achieve 'dimmed')

I did that years ( about 16 ) ago and the flicker was terrible.

The alternate circuit requires Live on the NO contact and Neutral on the NC contact of a C/O relay and that is a recipe for arcing disaster.

a system that will only work with incandescent lamps/bulbs

Long live the incandescent

 

[Harry Bloomfield]

Given that he's talking about a system that will only work with incandescent lamps/bulbs, I did wonder why he did not just have a single lamp/bulb in series with a diode (to achieve 'dimmed'), with a switch (or relay contacts) across the diode to 'short' it for 'full brightness'.

Perhaps the original install pre-dated cheap diodes with an adequate voltage rating?

 

[bernardgreen]

Perhaps the original install pre-dated cheap diodes with an adequate voltage rating?

The flicker was due to the lamps being switched ON and OFF 50 times a second on the half wave rectified AC

 

[JohnW2]

Perhaps the original install pre-dated cheap diodes with an adequate voltage rating?

I was using pretty cheap (all I could afford in my youth) 'high voltage' diodes in the 60s, so I'm not sure how old you think bernard's 'original install' may have been

Kind Regards, John