hi folks,

last week I had the brilliant idea to dim my traffic light so it would blend in better with the Christmas lights and, on top of that, it would not visually blast us out of the rec room when it was turned on other times of the year.

viewtopic.php?f=2&t=332311

as stated in the thread, even 25 watt bulbs were just too much. no sunglasses are needed now.

since that worked so well, I found another application for using a diode for dimming holiday lights.

since the early 80's, I have had a few of the mini 10 light candelabras that I bought at Kmart when I was a teen. I've always liked these but they were always too bright.

anytime I would put them with a Christmas display, their luminance would just drown out anything around them, [really] light up the room wherever they were, and give one a suntan in the process.

tonight I added a 1N4007 with the power cord on a few of these mini candelabra sets and the results were just as welcomed as when I dimmed the traffic light.

all is well. they blend in nicely with all the vintage decorations and lights.

the missus is very happy too b/c she never did like them for the above reasons.

also, these bulbs have long filaments in them which makes them so bright and very warm. they are nice and cool now. finding exact replacements is hard to do and the regular mini 12v bulbs don't look correct b/c of their regular sized filament.

they should last another 35 years by being dimmed down and look much better too. the pics don't really do the difference any justice, but they are down around 50% brightness and actually look "normal" now.

...too bad I did not think of this in 1982.

Christmastime just gets better and better around here.



steve

I have been dimming all of my Christmas lights with diodes for the last 30 years, outside and inside.

Dave

excellent

if i knew then what i knew now, i'd be dangerous.



steve

Steve, I have an extension cord with a diode in it as well for just such an occasion. Lowering lamp brightness or the crock pot temp for Sous Vide steaks. Sometimes I use it for testing when DC is needed like with a bulb in series to charge a battery or run an AA5.

I'm a fan of diode dropping, but it has a downside. The bulbs wind up lasting so long I forget when a fixture has a diode in series.

A few weeks ago an encapsulated halogen narrow flood that illuminated a showcase of toobs burned out. Went crazy trying to figure out why my replacement LED's didn't look quiet right until I measured the socket voltage and a dimmed light bulb went off above my head.

There is something about diode dimmed lamps that respond without thermal lag.
i.e. LED.

They do a bit of a strobe, which is noticed, when you walk by. The very first
LED Christmas light sets were like this, in addition to being dim compared to
the ones available now.

Nice info guys .Definitely got to dim those bright blue and green LED bulbs.They are too bright for my taste.They off set the over all light balance and ruin the looks of the tree .

For a set of nearly 50 C9 christmas lights I use in my 12' X 12' building I used a film speaker crossover capacitor in seies with the power plug.

Dims the lights quite nicely and also provides a soft start given the lights take about a second to reach the max brightness they will get on the reduced line voltage.

Suppose that's due to the cold resistance of the filaments being lower so greater current is drawn which reduces the voltage out of the capacitor then as the lights get brighter the resistance increases and the voltage goes up.

The downside is that it is load dependant.

The diode does seem like it would be the better option.

I did the same thing for our tree lights, and my wife loves the new look. The bulbs now look almost gold which matches the gold ornaments.

Tim,

When dimming lamps I would use a regular replacement for your halogen bulb if available because you aren't getting the benefit from the extra amount you are paying for the halogen bulb. The "halogen cycle" only works when the filament and gas mixture is hot enough and for the typical halogen bulb it needs to be running at 75-80% brightness for the redeposition of evaporated tungsten to occur. You aren't really damaging the halogen bulb by dimming it but the life of it will be the same as a regular incandescent bulb (except at a higher price) and you may also notice decreasing light output as evaporated tungsten more quickly darkens the much smaller internal envelope of the halogen/filament capsule.

I ran into this issue many years ago when I installed a cool looking and expensive halogen bulb in an outdoor entry light which ran at a reduced brightness setting until the motion sensor was triggered and it went to full brightness. I was surprised at the relatively short bulb life and when I did some research I learned why and realized that a halogen bulb wasn't a good choice for that type of fixture.

Rodger WQ9E

So, what if you made a chord to wire two strings in series? Wouldn't that provide the dimming effect without altering anything?

If bulbs were incandescent and the strings were the same it would work but
would present a major safety problem.

The connection polarity would vanish.

Most wouldn't care. An electrician could ruin Christmas by starting the first fight
of the season.

Why would you say that? Why would it be a safety problem? All you are doing is changing the current from AC to pulsating DC.

The female receptacle on the end of a string of lights does not feed through the lights but from the male plug on the other end, so connecting many strings together will not be a problem as long as the rectifier diode can handle the current.

Dave

as for the traffic light and these mini candleabras, i will always want them to be dimmed with the diode over their original brightness. that is why i permanently put the diode in their power cord.

i have temporarily tried a diode on many of our regular christmas lights. they are too dim for our liking.

steve

that is a great idea and i have thought of that already, but i have temporarily tried a diode on many of our regular christmas lights. they are too dim for our liking.

so, i've done this for the past couple years:

http://www.antiqueradios.com/forums/vie ... 2&t=288546

as for the traffic light and these mini candleabras, i will always want them to be dimmed with the diode over their original brightness. that is why i permanently put the diode in their power cord.

steve

I believe that Scot was talking about was something different. No diode. Have one string in series with another. So each gets 60 volts AC.

Strings of incandescent C7 have the socket shell connected to the wider pin (N)
but two in series, would only have half of the lamps with shells connected to (N).

I put a diode in series with the lights in an angel topper back in the 70s. Interesting thing is I never had a bulb burn out in it. Finally had to retire it though as it getting a bit worn and tattered. Lights still worked though, how often can that be said for a string of those mini push-in bulbs ?

Another trick is to use diodes on strings, some one way, some the other way.

Run on AC, all light dimly. Running the whole system, sourced through
a reversible diode, the others light up. With a timer relay, it could alternate.

A little off topic, but:

I once saw a interesting setup. What I saw was a wooden board with two light sockets and two push-buttons mounted on it. The two sockets and two buttons were wired in series with wires on the surface of the board. A power cord was connected to each end of the series circuit. Light bulbs were in the sockets. Push one button and one light would light. Push the other button and the other light would light. Push both buttons and both lights would light. Swap the bulbs and see that a specific button would light a specific bulb no matter which socket the bulb was in.

The secret. Each button had a diode wired across it under the button where you could not see it. One with the diode one way and the other with the diode the other way. Each bulb had had the base removed and a diode installed inside the base with the base then re-installed. One bulb one way and the other bulb the other way. The diodes were across the filaments.