Maker Pro
Maker Pro

Half wave rectifer ???

YosDad

Feb 23, 2011
5
Joined
Feb 23, 2011
Messages
5
Many years ago I purchased little buttons that stuck onto the base of incandescent light bulbs. At that time I was told they contained diodes. When used, the buttons dimmed the light output of the bulb about 30% but created a nice warm golden glow, and also with my experience extended the life of the bulb tremendously. My question is:

What was inside this button? A diode? Did it actually chop the AC sine wave and create a sort of DC voltage? I would like to duplicate this in a cost affordable manner on some incandescent bulbs I have around my patio, for both the light quality and the life of the bulb. Can I wire a diode (if this is what is necessary) into each bulb circuit and get this effect?
If so, considering each bulb is currently 60W 120VAC, what specs for a diode would I be looking for? Thank you for your reading and hopefully helping me with this issue.

YD
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
You would be looking for a diode with a 200V rating (or higher) and ratd for 1A. The diode would have to allow for a significant surge current as the lamp is turned on.

The diode delivers pulsed DC to the bulb.

The power consumed would be a little over 30W.

Yes, you could wire a diode in series with a lamp to get this effect.

The original circuit would have contained a switch and also would have kept the mains wiring out of reach -- which is important if you don't want electric shocks.
 

Resqueline

Jul 31, 2009
2,848
Joined
Jul 31, 2009
Messages
2,848
I'd expect those buttons to contain an "ordinary" triac dimmer (at a fixed setting). Just wire in an ordinary dimmer to your lights and set it somewhat below maximum.
 

YosDad

Feb 23, 2011
5
Joined
Feb 23, 2011
Messages
5
I already have a regular rotary type wall switch dimmer in the circuit, so are you saying that I already have it and don't realize it? If so, great.

YD
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
I'd expect those buttons to contain an "ordinary" triac dimmer

Possibly, but "diode" dimmers do exist. See here:

Reducing the voltage applied to a light bulb will reduce the filament temperature, resulting in a dramatic increase in life expectancy.

One device sold to do this is an ordinary silicon diode built into a cap that is made to stick to the base of a light bulb. A diode lets current through in only one direction, causing the bulb to get power only 50 percent of the time if it is operated on AC. This effectively reduces the applied voltage by about 30 percent. (Reducing the voltage to its original value times the square root of .5 results in the same power consumption as applying full voltage half the time.) The life expectancy is increased very dramatically. However, the power consumption is reduced by about 40 percent (not 50 since the cooler filament has less resistance) and light output is reduced by reduced by about 70 percent (cooler filaments are less efficient at radiating visible light).

But yeah, a regular dimmer does the same thing, but better.
 

Resqueline

Jul 31, 2009
2,848
Joined
Jul 31, 2009
Messages
2,848
It would make more sense that they simply put a simple diode in there, considering the small space available - and how long ago it is since they were marketed.
But personally I wouldn't want a flickering & orange light bulb for any purpose or benefit.. These buttons couldn't have become very popular then, or could they?
DC is not the best waveform for a high-voltage bulb either, as you get a one-way material wear at one end of the filament due to the electron flow in the vacuum.
Or so I heard..
 

YosDad

Feb 23, 2011
5
Joined
Feb 23, 2011
Messages
5
These were marketed in the 80s. They were $1 each (bulbs were really cheap then, so $1 was a lot to add to a bulb). They didn't flicker, they just darkened the output a bit and took away a harsh look and made the a regular frosted bulb have a soft warm glow, and in my experience using them on a lot of porch lights around the outside of my house, they lasted a long time, well over a year using them every night.

I'm a photographer by profession and light and the quality/color/intensity of light, even just my living space is very noticeable and important to me. I don't like direct, harsh light, I am looking for softer, smooth and warm indirect light. Considering the effect that a standard dimmer does, maybe the comment in an earlier post is what I should just stay with.

YD
 

YosDad

Feb 23, 2011
5
Joined
Feb 23, 2011
Messages
5
Will a regular Home Depot type rotary wall mount dimmer produce a DC output? If not, then I'm back to adding a diode to each light, right?

YD
 

Resqueline

Jul 31, 2009
2,848
Joined
Jul 31, 2009
Messages
2,848
Ok, thanks for all the info. I've been wondering about the technology incorporated in those buttons since I saw them advertised - in the 80's I guess.
A simple ordinary diode should make a bulb flicker noticeably. Maybe they're more than just ordinary diodes then. Perhaps they incorporate a diac?
Triac dimmers produce AC, no worries there.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
Just to expand on what Resqueline said...

Triac dimmers produce AC at the line frequency -- so that's 60Hz, or 120 half cycles per second. A triac dimmer varies the shape of these half cycles so that less or more power can get through. If you have any flickering, it will be at 120 Hz.

A diode only allows half cycles through, so for 60Hz, that's 60 half cycles per second. Any flashing will be at 60Hz.

Lower frequency flashing will me more noticeable than higher frequency flashing, so a triac will produce less visible flashing (for the same light output).

The filament in a light bulb has significant lag, so at higher frequencies, the temperature (and therefore the light) would not change very much between pulses.
 

YosDad

Feb 23, 2011
5
Joined
Feb 23, 2011
Messages
5
So the rotary type dimmers from Home Depot, are these triac? Or something else? And is the output AC or DC?

thanks

YD
 

Resqueline

Jul 31, 2009
2,848
Joined
Jul 31, 2009
Messages
2,848
I'm sorry if we confused matters for you. ;) Afaik; 96% of the dimmers available on the (world) market are triac based, and all (100%) produce AC on the output.
The remaining types (4%) are a new variety, based on transistors (of some sort) and can be identified by their small size, light weight, & absense of buzzing.
 
Top