stupid Q. does light on dimmer use less electricity?

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gar said:
Are there any dimmers using a single SCR and only modulating the on time of every other half cycle? This would mean there always was one full half cycle, call it the negative half, and the other, the positive half was phase modulated. I doubt such exists.
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rattus said:
It is more instructive to say that a portion of each lobe is switched off beginning at the zero crossing just as the diagram indicates. iIn theory, the OFF time can vary from zero to 180 degrees--full ON to full OFF.

I don't think any dimmers use SCRs. Like you say, they wouldn't work very well.
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From what I remember from my past electronics days, before Triacs were invented, and then before they became sheap and plentiful, SCR's were used in motor controllers and dimmers.

For full control, two SCR's could be connected in parallel, with the anodes and cathodes facing opposite directions, but most consumer controllers used single SCR's allowing a 0-50% control range or, with a diode connected across the SCR, a 50-100% range.

Here's a post I posted a while back: http://forums.mikeholt.com/showpost.php?p=704287&postcount=4
 
Besoeker said:
What kind of dimmer?
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Besoeker,
It is intended to be a simple representation.
There is a post which describes the oddness in more depth.

I recall (think I do) that you are an engineer, with BASF?
It is an idea from my engineers notebook, from the projects on Active Diodes.
The circuit boards are in an (inactive) instrument up on my shelf.
The Bilateral Active Diode circuit built around a setof Op-Amps, in a semi-logrithmic feedback loop, disclosed some characteristics about diode activity that was surprising. I was able to pass AC currents in the microAmp range through diodes and accurately control them. EL's think of .7 Volts as the forward voltage threshold, but I was working with a log curves and thresholds in the milliVolt range. I obtained documented results over a range of 5 decades down (from .7 Volts). The circuits showed the small reverse log currents on the Oscope. I posted some of these shematics and Spice implementations on the Linear Technologies website discussion forum, and had a number of comments. The Spice program is really handy for talking with the chips. Wish I had been able to use one in the beginning. Anyway, that was then.

Now I like to read what others are posting.
Today it is about Dimmers.
It seldom gets too deep that I can't follow.
 
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090301-1312 EST

This post goes off topic but the diversion results from going back looking at some history.

The first operational SCR and circuit was 1957. Without digging further the Triac patent application was 1961 and apparently commercial availability was 62 or 63.

From what I believe is the first edition of the SCR manual copyright 1960 I found the following SCR devices listed --- C10, C35, C36, C40, C60, and C70. Also listed are some Unijunction Transistors. The second edition is a 1961 copyright.

In 1961 I started some development work for the Charles F. Warrick, Co., on a conductive liquid level control using a small thyratron. Then in March of 1962 the GE sensitive SCR, C7, became available. C7U $8.10 each for 1 to 99. C7B (200 V rating) $19.80 each for 1 to 99. The maximum gate trigger sensitivity was 20 microamps and the typical rating was 5 microamps. This device was obsoleted by June 1962 by a new version of the C7. With the availability of this device the dessign was changed from a thyratron to an SCR. A patent application for this circuit was file August 29, 1963 and the patent was issued March 19. 1968. One of the patent office references was 3,165,688 by Gutzwiller.

Also in January of 1962 I was working on the development of a solid-state circuit breaker for Mechanical Products. In the experimental model I used back-to-back C10B SCRs for the power switch.

For some of the history on the SCR and Triac visit:
http://semiconductormuseum.com/Transistors/GE/OralHistories/Gutzwiller/Gutzwiller_Page12.htm
and read and listen to the material. These are only excerpts from his oral history. It would be interesting to hear the complete recording.

No author's name was on the first edition. Gutzwiller is listed as editor on the second edition. The first edition cost $1.00 and the second $1.50.

http://en.wikipedia.org/wiki/Thyristor

Things moved fast in those days, and today.
Probing the Internet many interesting things show up.
http://semiconductormuseum.com/HistoricTransistorTimeline_Index.htm
http://semiconductormuseum.com/Transistors/RCA/OralHistories/Herzog/Herzog_Index.htm
http://www.semiconductormuseum.com/Transistors/RCA/OralHistories/Herzog/Herzog_Page7.htm

In the RCA demo TV set of 1952 point contact germanium transistors were used. About 1953 the CK722 hobbyist junction transistor became available at about $4 each. I had thought it was 1954. Note at this time average wages may have been in the $1.25 to $1.50 per hour range.

In the summer and fall of 1952 I was stationed at the Brooklyn Naval Shipyard working on a tube project in a test group that was developing test techniques for the point contact transistor. To the best of my recollection there was no discussion at this time of the existence of a junction transistor.

On a project in 1955 on the development of an electronic ignition system we used some Delco germanium power transistors in the power supply to convert 6 V to a much higher voltage where a thyratron dumped a capacitor charge into a transformer to provide a very rapid rate of rise of the spark voltage.
History on the Delco transistors:
http://semiconductormuseum.com/Tran...t_EarlyPowerTransistorHistory_Delco_Index.htm

.
 
glene77is said:
Besoeker,
It is intended to be a simple representation.
There is a post which describes the oddness in more depth.

I recall (think I do) that you are an engineer, with BASF?
It is an idea from my engineers notebook, from the projects on Active Diodes.
The circuit boards are in an (inactive) instrument up on my shelf.
The Bilateral Active Diode circuit built around a setof Op-Amps, in a semi-logrithmic feedback loop, disclosed some characteristics about diode activity that was surprising. I was able to pass AC currents in the microAmp range through diodes and accurately control them. EL's think of .7 Volts as the forward voltage threshold, but I was working with a log curves and thresholds in the milliVolt range. I obtained documented results over a range of 5 decades down (from .7 Volts). The circuits showed the small reverse log currents on the Oscope. I posted some of these shematics and Spice implementations on the Linear Technologies website discussion forum, and had a number of comments. The Spice program is really handy for talking with the chips. Wish I had been able to use one in the beginning. Anyway, that was then.

Now I like to read what others are posting.
Today it is about Dimmers.
It seldom gets too deep that I can't follow.
Click to expand...
Glene
Yes I am an electrical engineer, but not with BASF. Maybe that's Lazlo?

I take your point about forward and reverse conduction in diodes. The 0.7V forward voltage drop is just a convenience for simple calculations often used to determine expected output voltage from a rectifier circuit.
On-state voltage, as you know, is rather more complicated than that.

Generally I deal with semiconductors in power applications, so a simple fixed voltage drop doesn't cut the mustard for thermal dissipation calculations.
 
To return to the O/P yes, dimming an incandescent lamp with a semiconductor dimmer will save energy, but not much.

If a 100 watt lamp is dimmed to the extent that it only consumes 50 watts, then the electricity consumed is halved (ignoring the very small losses in the dimmer)
But a 100 watt lamp dimmed so as to use only 50 watts, will give almost no light and is unlikely to be of any use.
If the 100 watt lamp is dimmed so as to give 50% light output it will use a lot more than 50 watts, since the efficiency is much less.
Better by far to use a 50 watt lamp.
 
bullheimer said:
you dim the light and a pot drops part of the load of the bulb. less voltage in the lamp, less wattage. the circuit is still 120v so it's still dropping 120V. if the R of lamp is 10 ohm, 120V = 12A so lets say it's 100 ohms for 1.2A. add a 100 ohm pot in the switch, now its 120V/200ohms=.6A half of the 1.2, duh. if P for the ckt is E x I 120V x 1.2A = 144W; 120V x .6A with dimmer = 72W, half the wattage. so savings of half to have the lamp on dim.

P for each load adds up to Ptotal. for dimmer switch you have 60V x .6A = 36 W and lamp is same,since i said R was the same, so 72W total for ckt with dimmer and lamp. gee just did that...

i don't know, i guess thats as it should be, but it seems to me that even with a dim light, those dimmers have big heat sinks, and can get hot, so they are using alot of the energy that i should be saving by having the light dim instead of bright.

i am no engineer, i don't really need all this math crap beyond ohms law, can somebody tell me if i would really be saving half the power if i have my light on half as bright? should i actually even care? regardless, i appreciate your time. seems like i am missing something but maybe i'm not. probably should be trying to think about something else.
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Yes and no.

When it is close to full brightness it will start to use more electricity than a straight-through switch. This is due to the efficiency of the power conversion of the SS device. If they would have an integral bypass switch at full load, then this issue would go away.
 
090302-1347 EST

On one bulb, 250 W, on a very crude test I found half power at about 88 V compared to 120 V for full power. Even at 60 V there is useful light output. 30 V is probably the lowest I would find useful.

For a useful nightlight I use a 757 pilot lamp on about 12 V. Doesn't burn out in any reasonable time. Probably will last 100 years or more. This is maybe too bright.

Efficiency of visible light output relative to input power favors running the bulb at its normal rating or higher. However, convenience, minimization of bulb replacement, and effect may favor running at reduced color temperature. Incandescent lamp bulbs are designed to have a balance of power input (operational cost), light output, initial cost (capital equipment), and life. Something around 1000 hrs is a typical design life. One could include other factors into the equation. For example, change the design to halogen, cost to replace bulb way high in the air, etc.

Often one wants easy adjustment of the light level and therefore changing light bulbs to accomplish this is not very practical. Switching on X of N lamps is not as convenient as turning a knob.

I have some hall fixtures with low wattage 120 v lamps that in thirty years have never burned out. These are on more or less continuously at very reduced light intensity and therefore have very long life. This is about 280,000 hours. Also the original GE dimmer has been in this function for 42 years and never failed.

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Besoeker,

(Diode) "On-state voltage ... is rather more complicated than that."

Life is a great experience!

I got a real high running diodes in reverse mode,
just to see what was there.
The spec sheets were plain enough,
but there was always something more.
What a blast shool was,
nobody ever told me what I could not try to do!

Aside,
At the Univ. of TN, we developed ET devices for use with crippled kids,
in the early 80's with an Altair 8000 and homemade PC cards, and Apple II's.
Those kids were/are trapped in their bodies,
I'm simply trapped in my memories.
They didn't get to live through regular school,
I got more than my fair share.
I think I got away easy.

Sorry, that was an Off Topic thing.
Bertrand Russell once said about being older,
that he could stair out the window if he wanted to,
and not to bother him!

I think the topic is about Dimmer Functionality.
 
rattus said:
I believe even the cheapies use a TRIAC which works on the rising and falling edges of the wave.

It should be noted though that dimming an incandescent lowers its efficiency.
Click to expand...

Rattus?

Please excuse my inexcusable irreference to the current topic, but how have been my friend?

Aside from that.

This question is easily handled using Ohm's law. If it hasn't already been mentioned I'll go through that.

I am so glad to see you again, or sort of, Rattus.
 
Well. I spent about 10 minutes writing a response but I appearantly pushed the wrong button accidently and the whole thing went away. One stupid button. I can't even imagine which one might do such a thing. It's never happened before, but it has just now.

I guess it doesn't that much matter how to sort out the difference between a reostat and a triac controled dimmer. Cause I'm sure not gonna do it again tonight.

What the . . . . button would do such a thing. Damn it.

Maybe tommorow I'll redo the thing.
 
weressl said:
Yes and no.

When it is close to full brightness it will start to use more electricity than a straight-through switch. This is due to the efficiency of the power conversion of the SS device.
Click to expand...

Not sure that's entirely correct......
For simple numbers take, for example, a 120V, 120W lamp being fed by a solid state dimmer. Nominal current is !A.
Fully phased on, the dimmer might drop a couple of volts, thus, in round figures, dissipates 2W. The lamp now has 118V across it. If its temperature didn't change, it would now consume about 116W.

Of course it isn't as simple as that. The temperature will change some which makes it not such a simple calculation. The power may not go down very much but I think it unlikely to go up.

P.S.
I apologise for having spelt your name incorrectly in an earlier post.
At least I remembered who the BASF guy was. :wink:
 
physis said:
Well. I spent about 10 minutes writing a response but I appearantly pushed the wrong button accidently and the whole thing went away. One stupid button. I can't even imagine which one might do such a thing. It's never happened before, but it has just now.

I guess it doesn't that much matter how to sort out the difference between a reostat and a triac controled dimmer. Cause I'm sure not gonna do it again tonight.

What the . . . . button would do such a thing. Damn it.

Maybe tommorow I'll redo the thing.
Click to expand...

That is the Realolman button. They appear on just about everything I come in contact with.... Even things that don't have buttons. :smile:
 
090303-0748 EST

physis:

I have suspected that it may be a key, but more recently I think it is an Internet problem. On many occasions I have had loss of material being composed.

I have removed 5 keys from my keyboard because they are a problem. These are caps lock, the two keys on the right adjacent to control, one of these is alt, and the two keys to the right of the space bar.

Caps lock being adjacent to A is a major problem. Some keyboards recess the right edge of the caps lock, this helps some, others do not. In the early IBM PC days and keyboards before had the control key in this location to the left of A, and alt was where control is presently. ALT did not come along until the IBM PC. The early PC keyboard was much better. Further the ten function keys were at the left and that was a better location than at the top.

An aside. CTRL, ALT, DEL should never be described as being done simultaneously, but rather as --- hold CTRL and ALT down and while down hit DEL. If one tries to hit CTRL, ALT, and DEL simultaneously it is often times possible that DEL occurs before both of the others, then the processor reset does not occur. In the past it has been the leading edge of DEL that causes the action just like most of the keys on the keyboard except CTRL and ALT which are modifier keys.

All of the keys where I removed the key top can be operated with a screwdriver or other appropriate probe when really needed.

.
 
gar said:
090303-0748 EST
I have suspected that it may be a key, but more recently I think it is an Internet problem. On many occasions I have had loss of material being composed.
Click to expand...
You may be right. There have been a number of occasions when I thought I posted something and when I looked later it had gone or more likely, never got posted in the first place. It has happened too often for it to be operator every time.

gar said:
I have removed 5 keys from my keyboard because they are a problem. These are caps lock, the two keys on the right adjacent to control, one of these is alt, and the two keys to the right of the space bar.
All of the keys where I removed the key top can be operated with a screwdriver or other appropriate probe when really needed.
Click to expand...
A novel approach!
A tad inconvenient though when you do need to use those keys....
 
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