Help needed with art project involving dimmers and pots

Hello!
I'm currently working on an art project in which I would like a dimmer that I can can control using 2 potentiometers. When one is all the way up, and the other is all the way down, I would like the incandescent to be at 50%, and when both are at max resistance, the light is extremely dim, or completely off. I would also like to use a touch on/off switch, to which I will connect a coin (as the item that needs to be touch to turn the light on.

I've done some research and I was thinking that I would purchase either the Velleman K8026 , or the Velleman K8028.

I would prefer to be able to use the K8028 because it has a soft on/soft off option. I would like to use that in conjunction with the 2 pots. Is this possible and where would I solder them on?

I also purchased a screw in touch on/off switch. Would this work with either one of the dimmers or would it negate the soft on/soft off mode of the K8028.

I'm still quite new at this, but I have made a few circuits. Here's one of my previous art works http://www.youtube.com/watch?v=HOV_C01lNaA I'm really excited to be incorporating electronics into my artwork again!!! Please give me some advice, and thank you for your help!

Trevor

 

Seems like the Velleman its you mention K8028 used momentary pushbutton switches to logically controll to light intensity in 4 steps. It seems to me that the kits are not quite what you need.

At first thought it seems that just using two wall dimmers in series with the light source could do the trick

 

The Vellmans appear to be triac dimmers with extra bells and whistles. I doubt the dimming would be additive, rather the more dim one would over-ride.

The "touch & glo" works as an on-off switch. If it is on, the soft start from the Vellman would apply. If the Vellman were on and the T&G were off, but then turned on, the soft start would not apply.

 

I definitely wouldn't waste the money on the Velleman circuit for the project you described. Soft-start switching sounds prudent as well as some isolation from the mains supply. Did you mention if you were using 120V/220V??

 

I am using 120V. How would I got about getting isolation from the mains? Sorry if any of my questions are basic, as I'm still learning. I can definitely get my hands on some wall dimmers and link them in series. However, how would I go about getting the soft-start? Thank you so much for your help!!!

Trevor

 

Also is there a way to limit the Watts of a light bulb? I found a great light bulb that fits my project but is 300W. I would love to use it however, the touch glow on/off only supports up to 150W. Is there a way I can limit the Watts? I guess with a power supply? If so, then would I have to connect the dimmers before or after the power supply? I'm guessing after to dim from 100W down?

 

Generally you would use a relay.

Adding resistance in series, which is what you are doing already with the two Pots(wall dimmers). If you took one pot and hooked it up to your 300W light, then turned the pot half the way between full on and full off, you would using the 150W instead of 300W, but your light intensity would vary logarithmically and you might end up with 1/4 - 1/3 the brightness. In other words you could use a third wall dimmer to cut the maximum power to our light bulb.

However, this is getting increasingly more difficult to work out when we are clueless as to how and where it will be used. You may want to supply some more project details.

 

I like the 3rd dimmer idea to limit the wattage.

Ok, for the whole scope of the project, it will be a paper mache woman. She will have a 300 W light bulb for a head (I liked the look and the glow of the filiment) I have the touch and glow touch on/off switch (a coin) wired where her privates are because sometimes it takes money to turn a girl on. Her nipples will be the 2 dimmers. She will have wires coming out of her arms and legs. This piece will be submitted for an art exhibition. She will be plugged into the wall and only by interacting with her, can you turn her on and set a "mood". Do you think this could work?

Also, how would I use the relay, and what type should I get? So soft on/off is out the door? Thank you for you help!!!

Trevor

 

Is the paper meche going to cover the head(lightbulb)? Do you like the "Glow" acceptable at 50% less power, that is between 50% and 0%? Will the bulb socket be safely isolated from the "user"? Why don't you try googling for "Touch Switch circuits" and "Soft on soft off circuits". I will do the same.

By the way, how flammable is paper mache? Have you ever tried burning it, outside of course!??

 

I think a 555 Timer circuit with relay. The 555 timer is triggered by a momentary pushbutton(attach penny to it). This sets off a timer for a set period, say 20 sec and triggers the relay(power isolation) for 20s. You can buy velleman kits for variable timer relay circuits.

But:
If you place in front of this circuit a 4017 decade counter with varying resistances on the outputs it can sudeo randomize the time the lightbulb will be lit up, say between 1s and 30s, thus the user hase to work harder to keep the girl happy! I hope I'm not getting a bit ahead of myself here..


These circuits can be run with a 9-12V wall adapter, in other words isolating the 120V house current from the user.

When I get a few minutes I will try to draw up a circuit for you.

 

Haha! iONic, I like the way you think! However, I think with this current project, I would like for her to be more functional, so on when the touch button is on, and off when the touch button is off. BUT I think I will use the cirucuit you talked about with verson 2.0. You know what, if it's not too much trouble, both would be great. I'm starting to really like the idea that you mentioned. Because most of our lives is around trying to keep a girl happy! It's shocking really. We really don't have AMPle time for WATT they really need. Hmm...I don't know where that came from!

Also by running an adapter, will that still be able to light the 300W bulb at 0-100W? I was hoping for the usual light plug, but it's a minor detail.

That was a great idea mentioning the possible flammability of the material. Maybe with the upper portion of the figure use tin foil with a few coats of spray enamel, so as not to conduct in the off chance she gets jarred.

As for the soft on/off, I found this link:
http://www.electronic-circuits-diagrams.com/designimages/designckt1.shtml

It seems that this would not work with the touch on/of screw in light socket. Could I link a simple touch on/off switch to it and I could have the reset in another area. Do you think that would work? Also apparently the circuit is to be operated at 9V. Mathematically, how would one figure out what would be needed for 120V or something that works with the wall adapter? This would be perfect is the 9V adapter is adaquate!

After I'm done with the project, I'll definitely post a video of her in action!!!

 

Hopefully I can draw the circuits up tonight for you, but don't quote me. What experience have you had assembling small circuits and do you have the equipment? I know you mentioned buying a kit at one point and this might still be feasibly, quicker, and less expensive. Do you have PCB's Solder, Solder Iron, Flux...? By the way, is there a deadline?

You might be able to get away with just a 9V battery, or two.. for operating the control circutry. This doesn't change the need for the wall plug for powering the light bulb.

Have you ever put put tin foil in a wall socket, or for that matter even a strip of aluminum gum rapper? DO NOT TRY AT HOME!!! I did do this in Junior High and got not only a big pop, but received an in school suspension. I don't know how you plan to attach the light bulb, in a regular table lamp light socket. You need to tell me...!! DO NOT use the aluminum foil.
The best solution would be to wrap the socket and nearby wiring with good electrical tape.

Also: did you say that you are covering the bulb itself or not?

As for the soft on/off, I found this link:
http://www.electronic-circuits-diagrams.com/designimages/designckt1.shtml[/QUOTE]

Let me talk you out of this option. I think that you want the interaction and therefore do not want to leave the circuit on. This also reduces the possibility of heat buildup from the bulb. The simplest 555 timer circuit can be setup for a simple predetermined time and then shut off for the next user to "stimulate" the circuit. A second reset momentary switch could be placed somewhere else on the body that would turn the timer off sooner than set. In fact more than one can be used in the "turns me off" zones to warn the user that She's not satisfied with the actions of the user. Maybe even a random call of Rape!!!! Kidding!!!

Thus, given the increased heat buildup heat for the light bulb and the reduces possibility of user interaction I forget the turn-on indefinitely method.

The 9V will not be powering the light bulb as I stated above but only the control circuitry.

 

Sorry, but I see a number of safety issues with what's being planned.

This being an interactive artwork, there is a high probability that the work may be knocked over and broken, exposing those in the area to broken glass (from the bulb) creating a laceration hazard, and line voltage (from the then-exposed filament and leads).

Dimmers have SCRs (silicon controlled rectifiers) or TRIACs (bi-polar version of SCR) in them. They work by allowing only a portion of the AC sine wave to pass. Whichever dimmer has the lowest setting is the one that will control the light intensity. They weren't really designed to be run in series.

"Electrical tape" is not a suitable material for electrical insulation, particularly around a heat source such as a lamp. The adhesive used on electrical tape eventually gets "gummy" and the tape unwraps, exposing the wiring underneath. Heat greatly accelerates this deterioration of the adhesive.

I do not know any electricians that use "Electrican's Tape" for it's insulative properties. I've seen it used for marking wires, and as an accessory item for fishing wires through conduit, and temporarily securing items - but not as insulation.

Our OP (original poster) needs to change tactics. Think of how you could use something else for the 300W lamp; perhaps a clear plastic bottle shape. You may be able to re-form a bottle that's somewhat close in shape to what you want with careful application of heat and (perhaps) light air pressure; like a glassblower, but at lower temperatures.

As far as the lighting itself, you should be using low voltage LEDs. This will result in a relatively "safe" display; if it's knocked over, a faux plastic "bulb" won't shatter, and even if someone got carried away and tore it apart, there should not be a high voltage hazard (if you're using a UL-listed supply).

If you have your heart set on using incandescent lamps, you could use 12v automotive lamps. These would be relatively easy to control using widely available components. At any rate, such a display should be capable of operating from 28v or less.

Your concept is whimsical and I feel that it has merit. (I'm not the artist, my spouse is.)

However, I feel strongly that you must have a safe exhibit.

1) Paper mache' (flammable)
2) High voltage (shock hazard)
3) Glass (breakage/laceration hazard)
4) Heat (see 1)

I suggest that if you have more than the 1st item, it will need to be behind a protective glass/plexiglas wall to protect the public, which will defeat the interactive nature of the exhibit.

 

Hello sgtwookie,
I understand your concern for safety and I have a similar interest because what good is artwork if it hurts people? Well, I guess some artwork is meant to hurt people, but let's not go into the meaning of art here.

To address the issues, that you stated:

1) Paper mache' (flammable)
This is true, however, I am very resourceful and I have a Hardware store close by. There are ceramic light fixtures as well as other fixtures that I can purchase that are specifically for lightbulbs and have the proper ratings for safety. If installed, I would make sure that it shielded the paper mache.

2) High voltage (shock hazard)
The reason I am asking for help here is to make sure that the wiring would be safe. I am looking to make this piece a closed system where there will not be any exposed wires, etc. So there will be no possibility of shock unless someone unscrewed the lightbulb and stuck their finger in.

3) Glass (breakage/laceration hazard)
Regarding glass breakage, the piece will be securely mounted onto the wall by way of secure mounting points. It will not be able to fall off because someone brushes against it or is a bit aggressive with her. Only if they purposely try to pull the piece off the wall will it come off.

4) Heat (see 1)
Obviously with a lightbulb, there will be heat, but if the wattage is limited and precautions are taken, I don't see why this will not work like any other light fixture. I feel that free standing fixtures will be more dangerous than this because they can be knocked over and catch curtains and other cloth on fire.

Hopefully I answered your questions regarding the safety of this piece! Now onward to the logistics!

 

Let me talk you out of this option. I think that you want the interaction and therefore do not want to leave the circuit on. This also reduces the possibility of heat buildup from the bulb. The simplest 555 timer circuit can be setup for a simple predetermined time and then shut off for the next user to "stimulate" the circuit. A second reset momentary switch could be placed somewhere else on the body that would turn the timer off sooner than set. In fact more than one can be used in the "turns me off" zones to warn the user that She's not satisfied with the actions of the user. Maybe even a random call of Rape!!!! Kidding!!!

Thus, given the increased heat buildup heat for the light bulb and the reduces possibility of user interaction I forget the turn-on indefinitely method.

I feel that for an art exhibition the time limitation for the piece would be good, but I guess I always imagined the piece in my living room, and it would be a functioning piece of art, by doubling as a lamp. Do you think this can be done?

Also, should I just forget the soft on/off aspect of the light?

The 9V will not be powering the light bulb as I stated above but only the control circuitry.[/quote]

I feel we're getting close to coming up with a circuit. I have news papers ready and I'm heading to thrift stores in the future for other products.

Also sgtwookie posed this problem:
Dimmers have SCRs (silicon controlled rectifiers) or TRIACs (bi-polar version of SCR) in them. They work by allowing only a portion of the AC sine wave to pass. Whichever dimmer has the lowest setting is the one that will control the light intensity. They weren't really designed to be run in series.

Is this true? If so I guess I don't mind that each could dim exclusively, although I would prefer it the other way. As long as the wattage does not exceed 100W I think we should be ok!