Heating Element Control

If it plugs in, post it here.

Moderator: Site Moderator

pintoshine
Distiller
Posts: 1132
Joined: Sun Aug 20, 2006 1:30 pm

Post by pintoshine »

I'll look them up.
pintoshine
Distiller
Posts: 1132
Joined: Sun Aug 20, 2006 1:30 pm

Post by pintoshine »

For the 240 volt circuit, I used Mouser P/N: 74-4SP10
400V .1 uf MET POLY
The description is Vishay/Sprague Ployester Orange Drop Capacitor.
the variable resistor is P/N: 313-2441-500K
The discription is D-Shaft 500K
Tiawan Alpha 24mm Carbon Potentiometer.
cwood
Novice
Posts: 13
Joined: Sat Oct 14, 2006 2:41 pm
Location: houston, tx

Post by cwood »

Well, that 1st schematic looks like what I am looking for...simple, cheap, and gets the job done. Anybody else have one built as of yet? Any operating characteristics youo'd like to share ??? I'll be using it with my 1500-Watt elemenr (120V) with my Milk Can boiler & 2" x 48" column......I have great expectations .........

Thanks all...

CW
masonjar
Swill Maker
Posts: 204
Joined: Wed Oct 11, 2006 5:27 pm

Post by masonjar »

One nice modification is to the third circuit and replace the reed switch with a ttl level, isolated photo diac. This allow switching from the parallel port on your computer. This is what I use. I wrote some nice c# software to allow me to turn the element on and off rapidly with a known pulse width.
That sound pretty neat. How do you keep it synchronized to the 60 Hz AC? Have you ever played around with microcontrollers?

In the case of a 40 amp triac, it could take as much as 4 amps to trigger it. A variable resistor, capacitor combo can't deliver that kind of current.
That's not quite true. Yes, there is a practical limit when considering component size and cost, but capacitors can easily supply large currents for very small periods of time - and it doesn't take very long to turn on the triac. The important aspect for the functionality of this circuit is the time constant of the capacitor and resistor. If you need more current to supply the gate, then you can double the value of the capacitor and also reduce the value of the resistor by half. Then the time constant will be the same, and you will get a larger amount of energy to trigger the gate.
pintoshine
Distiller
Posts: 1132
Joined: Sun Aug 20, 2006 1:30 pm

Post by pintoshine »

I agree with you completely. The problem I keep running into is that most of the cheap potentiometers are carbon type. These are a buck or so and are only rated for 1/4 watt. Yes I could buy 25 watt wire wound but their upper range is only 2 to 5 kohm.
I was trying sto say that the components in the off the shelf dimmer can't support replacing the triac for a larger one. Besides, these days there is no diac in the off the shelf ones. The diac is built into the TO-220 case with the triac.

As far as the synchronization with the line current is concerned, it takes care of itself. The software uses a one second pulse timing. I select how much of a second it stays on. If I trigger it in the middle of a positive or negative swing, it comes on. When it is turned off the triac stays latched until it crosses zero.

I could be off in time as much as one half cycle or 8.3 milliseconds. The software has a pulse width from one to one thousand milliseconds in 10 millisecond increments. So the error will be < 1% of the scale. So if i set it for 65% duty cycle it will vary from 65 to 65.83 and 75% will be 75 to 75.83%. The error is no bother. The heating element has a very easy time integrating the RMS value of the voltage. I have to admit it is annoying to run a batch with the lights dimming for a part of a second every second.
With my air cooled condenser I had to throttle back my 4.5kw element to 2.2kw. I have built myself a 9kw 304L stainless steel, water cooled condenser to allow me to run straight out.

By the way, the cheap 40A 240 VAC solid state relays are my choice when interfacing the computer.

I'll have to post some screen shots of the software on my web site.
masonjar
Swill Maker
Posts: 204
Joined: Wed Oct 11, 2006 5:27 pm

Post by masonjar »

I was trying sto say that the components in the off the shelf dimmer can't support replacing the triac for a larger one.
Okay, I see what you mean. I thought your statement in bold was more of a general 'this can't be done' thing instead of a 'this can't be done with off-the-shelf dimmers'. Sorry about the confusion.
As far as the synchronization with the line current is concerned, it takes care of itself. The software uses a one second pulse timing. I select how much of a second it stays on.
Got it. If you wanted to get rid of the light dimming issue, you could add an AD converter to your parallel port and set your software to start the pulse periods at the zero crossings that you measure. Then you could shorten your period to something that wouldn't be visibly noticeable. Say, have you ever done any microcontroller programming? This is the kind of thing that microcontrollers do better than PCs and you already can program in C, so you wouldn't have to do much learning.
pintoshine
Distiller
Posts: 1132
Joined: Sun Aug 20, 2006 1:30 pm

Post by pintoshine »

Yes. I've done tons of microcontroller programming.
I am somewhat of an assembly language guru
That could be a forum bigger than this one all its own...
But lets not go there, cause I'll get banned for flooding the forum...


The light dimming issue in my shop is because it has 200 feet of large wire,
#2,
supplying it juice and the 4500 watt element literally dims the lights when it is turned on.
tonkyman
Novice
Posts: 37
Joined: Sun Jul 16, 2006 7:09 am
Location: Way down in Dixie

Built one

Post by tonkyman »

Hi cwood and pintoshine,
I built the little unit yesterday. I have to say it's pretty slick. I used mostly stuff from around the house so it's not a professional as I'd like for it to be but it seems to work great. When I build my next one I'm using a project box instead of gang conduit boxes because it really limits how things go together.

I did take lots of pictures as I was building it and I hope to get them posted so I can share them with you.

I've only tested it with a 200 watt light bulb because I was to lazy to put water in the still and try it that way. I will be soing more testing over the next few days just so I can make a small temp chart that follows my dial. I know it wont be perfect but it'll get me in the ballpark.

Thanks pintoshine for the circuit and for taking the time to explain it all, I've learned a lot of really cool stuff.

Later,
Tony T
Tony T
Just tryin' to learn the art.
masonjar
Swill Maker
Posts: 204
Joined: Wed Oct 11, 2006 5:27 pm

Post by masonjar »

Yes. I've done tons of microcontroller programming.
I am somewhat of an assembly language guru
That could be a forum bigger than this one all its own...
But lets not go there, cause I'll get banned for flooding the forum...

The light dimming issue in my shop is because it has 200 feet of large wire,
#2,
supplying it juice and the 4500 watt element literally dims the lights when it is turned on.
Yeah, there are lots of microcontroller forums out there. You just sounded like an electronics tinkerer, and I've found microcontrollers to be the most fun by far when it comes to that.

I was saying that if you shortened that 1 second period down to half the period of one 60Hz cycle, then you wouldn't notice the lights dimming. That would require synchronizing by measuring the 60 Hz wave, but you already know that...
tonkyman
Novice
Posts: 37
Joined: Sun Jul 16, 2006 7:09 am
Location: Way down in Dixie

Dead

Post by tonkyman »

Well, while testing my little pride and joy with a 200 what bulb connected it just stopped working. After a short troubleshooting session I beleive it to be the light dimmer has gone bad. I can apply a voltage to the gate of the triac and the light will turn one but nothing through the dimmer. It was working fine and just stopped. Do you think it's just a bad dimmer (cheap wal-mart unit) or is something wrong with the circuit?? I may not do much right but I follow instructions to the letter when I do something so I don't think I did anything wrong. I have checked and double checked and find nothing wrong in the wiring.

Any ideas?? I'm replacing the dimmer with a better unit tonight and I'll try again.

Later,
Tony T
Tony T
Just tryin' to learn the art.
pintoshine
Distiller
Posts: 1132
Joined: Sun Aug 20, 2006 1:30 pm

Cheap Crap

Post by pintoshine »

I bought a cheap dimmer the other day that did the same thing. It was a 300w. I replaced it wiht a 600w because my local store was out of the bargain basement one's and it is doing fine. I don't know if there is a relation.
Stillhead

jk

Post by Stillhead »

Just a couple of thoughts, though I am not really at the level of electrical knowledge that you guys obviously are.

I was just thinking that a couple of easy solutions would be:

1) switch the 1500W 120V heating element with a 3000W, 230V element and run off of 115V. This would effectively give you 750W of power.

2) Run a diode and a switch. The diode must be >10A. When the switch is on, the electricity will run through providing 1500W. When the switch is off, the electricity will run through the diode, providing 750W.

I am not sure how correct I am or if it is more complicated than this, but I am sure one of you can tell me,

Bryan.
masonjar
Swill Maker
Posts: 204
Joined: Wed Oct 11, 2006 5:27 pm

Post by masonjar »

Yep, you are correct. The diode would need a heat sink in your second suggestion though.
Stillhead

Post by Stillhead »

Would this generate much heat? Does that mean that the excess energy is just translated into heat? I am looking for a solution that saves on electricity.
masonjar
Swill Maker
Posts: 204
Joined: Wed Oct 11, 2006 5:27 pm

Post by masonjar »

It doesn't turn the excess power into heat. During the time the diode is off, it doesn't use power. When the diode is on, it will drop a volt or two, and dissipate maybe 5-10 Watts of power. It's not that big of a waste of power, but depending on the diode you get, that might be enough heat to fry itself it didn't get a heat sink.
tonkyman
Novice
Posts: 37
Joined: Sun Jul 16, 2006 7:09 am
Location: Way down in Dixie

Post by tonkyman »

Hey Pinto,
This is how I had to connect the dimmer to make it work. What Am I doing wrong?? It works fine like this but it is not like your diagram. I'm also going to have to put a much bigger heatsink on it because it gets HOT!!!!! I am using the conduit box as the heatsink and the steel doesn't move the heat as well as aluminum (sp?). I have some big CPU heatsinks and fans that i may use to cool it. I am for sure moving the entire thing to a nicer project box This thing is a keeper. As I recall this was how your first diagram looked.

Image

If this is wrong tell me how to fix it. NOTE!!! My drawing above is WRONG! Pintoshine's schematic further up the forum is correct. ** See my post further down this thread.

I connected it to the 600w coolant heater on my Mercedes The last two nights and it's worked great. The 600w heater is a little much for the 2.4L diesel in a 240 because it doesn't get very much below 25-30 degrees down here. My shop is unheated so the heating problem with the triac was not a problem.

Thanks,
TonyT
Last edited by tonkyman on Sat Nov 25, 2006 7:46 am, edited 1 time in total.
Tony T
Just tryin' to learn the art.
masonjar
Swill Maker
Posts: 204
Joined: Wed Oct 11, 2006 5:27 pm

Post by masonjar »

Are you sure you aren't confusing the terminals on the triac? This schematic shouldn't work - however, if you flip the triac upside-down then it would work as you've shown here.
pintoshine
Distiller
Posts: 1132
Joined: Sun Aug 20, 2006 1:30 pm

Post by pintoshine »

:DCongratulations! You did a fine job at tinkering until it worked. :D

I think there might be an error on the schematic though. Shouldn't the resistor connect to the other side of the plug?
I am sorry for my mistake. I knew it was one way or the other. Trial and error seems to have revieled that the first schematic was the correct one for your dimmer.

I would have to say it is probably going to depend on how the manufacturer built the dimmer and both solutions are correct. Both ways will have to be tried if the first way doesn't work.

I'll make a copy of your picture and make sure both are available for future people to see.

I buy a lot of junk and salvage heat sink from http://www.bgmicro.com. A lot of times they have hugh ones for $0.99 USD. The one I have been using is about as tall as one of the outdoor recepticle boxes. I cut it down to fit half of the recepticle box with the other half covered by a single stainless steel switch plate. The fins stick out the front.
This is typical of the kind I usually use:
Image
These guys will move a lot of heat if the fins are mounted vertically.
Last edited by pintoshine on Tue Dec 12, 2006 7:51 pm, edited 1 time in total.
tonkyman
Novice
Posts: 37
Joined: Sun Jul 16, 2006 7:09 am
Location: Way down in Dixie

Found my mistake

Post by tonkyman »

Well! Masonjar is right. I went back to the data sheet and I had confused MT1 and MT2 on the Triac. This Triac is in a TO-218X case and the layout is (left to right) MT1 MT2 and Gate.

Image

I have it working but now that I know it is wrong I have to go back and fix it, just because I hate it when people don't follow instructions and I screwed up.

So for the official record the diagram in my previous post, while it works, is not the correct way to connect it.

Thanks guys, I just wish I was as sharp about all this stuff as you guys.

Later,
Tony T
Tony T
Just tryin' to learn the art.
stillvodka
Site Donor
Site Donor
Posts: 432
Joined: Sun Apr 23, 2006 10:13 am

Post by stillvodka »

Hello,

Have you thought about this company in the UK http://www.sutronics.com onclick="window.open(this.href);return false;" rel="nofollow, exactly what you need, just need to make a control box and incorporate a heat sink.
pintoshine
Distiller
Posts: 1132
Joined: Sun Aug 20, 2006 1:30 pm

Post by pintoshine »

tonky your doing real good. I have a good excuse for some of the things I know especially when it comes to electronics. I have a BSEE.

I looked at the suntronics link. Only one problem, most of us in the USA only have 120vac 60 hz available. I have a bit of a leg up in that I wired my shop for 240. Still I am building these controllers for 1/4 the retail cost. I also work for UPS and know the price of shipping from UK to USA. Ouch!
tonkyman
Novice
Posts: 37
Joined: Sun Jul 16, 2006 7:09 am
Location: Way down in Dixie

Post by tonkyman »

I had basic electronics in JC over 25 years ago and I’ve never had to use much of it since then. I'm amazed at what I've forgotten in that period of time.

I'm a network admin for 5 multi-million dollar corporations so most of the time my head is in a router manual, Microsoft white paper, or some other technical paper to keep me up to date (which never ends!!!). The only time I've really used any of my electronics was calculating loads for the backup generators in the data center (E over IR can be your friend).

Now if you want to know about Terminal Services, Network Load Balancing, DNS round robin or SQL clustering with failover ----- I'm your guy.

I've heard good and bad about the Sutronics units but this little $11 design is a thing of beauty. Had I looked at the data sheet more closely I would not have had a problem. This thing is so cheap and easy to build I can think of several uses other than heat control.

Since I'm going back and repairing the wiring I'm moving it to another box and taking lots of pictures. I'll post them when I'm done.

Later,
Tony T
Tony T
Just tryin' to learn the art.
CoopsOz
Distiller
Posts: 1172
Joined: Wed Aug 16, 2006 4:00 am
Location: Didjabringyabongalong

Post by CoopsOz »

Hey Tonkyman, when you post the pics.....could you also do a follow the bouncing ball instruction? I only ask because most of this thread is going straight over my head!
It is most absurdly said, in popular language, of any man, that he is disguised in liquor; for, on the contrary, most men are disguised by sobriety. ~Thomas de Quincy, Confessions of an English Opium-Eater, 1856
Stillhead

f

Post by Stillhead »

yes. I too wish to be presented with this ball.
tonkyman
Novice
Posts: 37
Joined: Sun Jul 16, 2006 7:09 am
Location: Way down in Dixie

Post by tonkyman »

I'd be happy too. This project is so easy and the price is right. You guys want me to do the 120V or the 220V version?? I don't have a use for the 220V but I'm sure I will later so I thought I'd do both. It's cheaper to order enough parts to build several units because the shipping is the same.

Later,
Tony T
Tony T
Just tryin' to learn the art.
CoopsOz
Distiller
Posts: 1172
Joined: Wed Aug 16, 2006 4:00 am
Location: Didjabringyabongalong

Post by CoopsOz »

I need a 240V one....is that gonna be an issue?
It is most absurdly said, in popular language, of any man, that he is disguised in liquor; for, on the contrary, most men are disguised by sobriety. ~Thomas de Quincy, Confessions of an English Opium-Eater, 1856
tonkyman
Novice
Posts: 37
Joined: Sun Jul 16, 2006 7:09 am
Location: Way down in Dixie

Post by tonkyman »

I'm thinking that a 220 - 240 can be the same unit as long as it's 60hz. The power company says I have 220v at the main but every time I've checked it it's closer to 235V.

Pintoshine or masonjar help me out here. I don't want to mislead anyone.

Also, pinto when you gave the components for the 220/240 unit:
For the 240 volt circuit, I used Mouser P/N: 74-4SP10
400V .1 uf MET POLY
The description is Vishay/Sprague Ployester Orange Drop Capacitor.
the variable resistor is P/N: 313-2441-500K
The discription is D-Shaft 500K
Tiawan Alpha 24mm Carbon Potentiometer.
Which circuit does this go with?? Just to clear it up you are talking about modifing the dimmer itself correct? If you don't mind, could you give me the drawing and a bit more instruction on the 240v model. I'm sorry for bothering you so much with this but I'm having a good time playing with it.

Later,
Tony T
Tony T
Just tryin' to learn the art.
Stillhead

d

Post by Stillhead »

I would like to see exactly how to build the 120V one. I wish to control a 1500W, 120V element.

Thanks
pintoshine
Distiller
Posts: 1132
Joined: Sun Aug 20, 2006 1:30 pm

Post by pintoshine »

Image
Here is a quick little schematic.
To get the pinout for the TO-220 chip I have to follow the leads in the dimmer closely.
The only thing I use off the store bought dimmer is the TO-220 part riveted to the plate and the plate itself. I strip all the other parts off and start from scratch. The potentiometer gets replaced with the new one and I solder the capacitor between it and the TO-220 lead.
I did check and the 600W dimmer works best. It can handle the 4 amps to trigger the power triac. I get these for $6.95 USD.
Last edited by pintoshine on Tue Dec 12, 2006 7:57 pm, edited 1 time in total.
tonkyman
Novice
Posts: 37
Joined: Sun Jul 16, 2006 7:09 am
Location: Way down in Dixie

Post by tonkyman »

Hi Pinto,
That make more sense now that I see it like that. I'll order some more goodies and qive it a try.

Stillhead,
I have pictures I'll try to resize and up load tomorrow. I'll give you a step by step for the one I have now but keep in mind it will need a better heat sink. After seing how pinto takes the dimmer apart I see that I could have mounted the triac on the plate of the dimmer and that would have been much easier.

Later,
Tony T
Tony T
Just tryin' to learn the art.
Post Reply