small, adjustable time delay 12v relay.

Good evening, all.

I'm about ankle-deep in a hobby project that requires four different 12v heating elements to be turned on, held on, turned off - with this cycle being repeated as long as voltage is applied. Currently, I'm thinking that four independent adjustable time-delay 12 volt relays would work for the task.

However, I don't have much experience with relays and I'd appreciate any suggestions or discussion on the matter before I make any purchases. I'm also open to using another method to achieve the same goal - if there was a project kit to achieve a similar end I'd be interested in McGuyvering it to fit.

Thanks,
Erik

Can you supply more information on what exactly you are trying to do.

Also, what kind of timing will be involved in the heaters?  Will they all be on or off at the same time, or will they be staggered with overlap.  It's really hard to advise on a system without having all the information.

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Kevin Pierson

KPierson wrote:

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Can you supply more information on what exactly you are trying to do.

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Absolutely.

One of my hobbies is making costumes of heroes or villains. With 'The Watchmen' coming out on March 6th, I'm working on a totally awesome costume based on the character Rorsarch. Using a color changing fabric responsive to temperature, I intend to have heating elements placed under a mask made of the aforementioned fabric that turn on/off at different times - creating an ever-changing pattern.

KPierson wrote:

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Also, what kind of timing will be involved in the heaters?  Will they all be on or off at the same time, or will they be staggered with overlap.  It's really hard to advise on a system without having all the information.

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I'll explain how the heating elements are laid out, and then explain the timing. The mask will have four 'zones'. For instance, 'Zone 1' would be heating elements placed on the cheeks, 'Zone 2' would be elements placed over the nose and so-forth.

Each zone would turn on and off independently. That way the mask doesn't present the same pattern all of the time. Ideally each zone would also have a different amount of 'hold', to better attempt to make it appear more random.

I apologize if my original post lacked information. I really didn't know how to approach this request without seeming overwhelmingly strange. :)

Thanks,
Erik

Ok we need more Info

All on at the same time?

One at a time in Sequence?

How much time between cycles etc. Explain better please.

Help us to help you???

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

hotwaterwizard wrote:

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Ok we need more Info

All on at the same time?

One at a time in Sequence?

How much time between cycles etc. Explain better please.

Help us to help you???

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All four of the circuits would receive power at the same time, but because they'd be time delayed, the heating elements would not all turn on at the same time.

They'd be one-at-a-time, with each heating element drawing from it's own circuit to the battery.

The time between cycles would be different for each circuit, but I'd say that a 'safe' guesstimate would be variable up to (maybe) six or eight seconds.

hotwaterwizard wrote:

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I adapted this Circuit for Relays.

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Thanks. From what I gather off the original site, changing the C1 value changes the 'sequencer speed'... do you suppose that is the time for 'on' or for the length of time the relay is held 'on'? Ideally, they'd be independent values.

How big are the heaters (voltage and wattage rating) that are going to be used?  That would dictate how exactly I would go about doing it - I would try to stay away from relays personally as they will just be an additional load on the battery.

The "issue" with a simple time delay circuit is that you won't have any randomness to the pattern.  You would need a much more intelligent controller to provide a 5-6 minute on/off pattern - this would give the illusion of randomness as most people wouldn't notice patterns repeating after that amount of time.

What kind of space do you have to work with? 

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Kevin Pierson

KPierson wrote:

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How big are the heaters (voltage and wattage rating) that are going to be used?  That would dictate how exactly I would go about doing it - I would try to stay away from relays personally as they will just be an additional load on the battery.

The "issue" with a simple time delay circuit is that you won't have any randomness to the pattern.  You would need a much more intelligent controller to provide a 5-6 minute on/off pattern - this would give the illusion of randomness as most people wouldn't notice patterns repeating after that amount of time.

What kind of space do you have to work with? 

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Truthfully, I don't know what kind of voltage/wattage I'm working with. I found some flexible heating elements by Minco at a local surplus store (Minco / Polimide Heaters) lacking in just about any information. When we started putzing around with them on a Variac, we came to believe they are designed for 12v, 1A.

Whatever company contracted them in the custom design that ended up there is wonderful for this project, though. I can take a picture when I'm at home tomorrow. Funky stuff.

And I'm all for moving away from relays, if I can find a better option. I was hoping that maybe there was an IC project out there just -perfect- for this, because it would be less draw and occupy less space.

Oh, and on space - I'm looking to mount this on something similar to a shoulder brace, with wires running up into the mask to the heating elements.



It'd be worn under a shirt and under a jacket, so it'd be neatly concealed.

What kind of battery are you going to use?

With a 1A heater I would recomend a 3A low on-resitance mosfet driver for each heater.  The low on-resistance will minimize the heat dissipation of the mosfet.

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Kevin Pierson

KPierson wrote:

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What kind of battery are you going to use?

With a 1A heater I would recomend a 3A low on-resitance mosfet driver for each heater.  The low on-resistance will minimize the heat dissipation of the mosfet.

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As of current, I'm looking into using a Makita tool battery pack. I'm not sure on the voltage, because I don't have them on hand - a friend of mine is working on checking a few he borrowed from the 'bad' bin and restoring as necessary.

here a simple idea would gun lock timers that are used for approx 15 sec time on work the amp capacity should be fine and might be easier to work in that config

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wiringfool eieioztztzt

Good morn', and a bump.

I wanted to drop in and let everyone know that while I appreciated your input, I found a solution in a circuit made by reuk. I ended up specially ordering four circuits, each with adjustable on and off times down to tenths-of-a-second.

I also ended up going with a 14.4 setup with a nice, dandy Makita Li-on battery pack. Mmmm.

So, thanks for your input - that's the end gameplan.

wiringfool wrote:

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here a simple idea would gun lock timers that are used for approx 15 sec time on work the amp capacity should be fine and might be easier to work in that config

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Unfortunately, that wouldn't have worked for the purpose - the on time is far, far too large. After I ran my tests with the heating elements and the hypercolor material, I needed on times as low as half-a-second and off times just about two seconds.

Will the circuits provide the "random" color change patterns you are after?  If you don't mind me asking how much were the four circuits your ordered?

Great thinking on a drill battery - I've used them for small projects from time to time and they are a great source for power.

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Kevin Pierson

KPierson wrote:

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Will the circuits provide the "random" color change patterns you are after?  If you don't mind me asking how much were the four circuits your ordered?

Great thinking on a drill battery - I've used them for small projects from time to time and they are a great source for power.

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They'll be random enough. Each one of them will be set independently of the others, so they'll at least seemingly 'pulsate', which is well enough. Each one was about 17 euros... or pounds. Whatever it was.

It'll be worth it in the end. Best superhero costume I've ever done. :)

what an awesome project! post pics when you are finished.