Heating System

[abuhafss]

Hi

Here is my circuit idea to quickly heat-up a tiny mold.

The circuit is self-explanatory. The pictures of the mold is also attached to give you the idea of the size of the mold.

Questions:

What kind of cables/wires should I use to connect the Transformer-Relay-Heater ?
What should be the amperage of the relay to switch on the Transformer?

 

[Militoy]

There’s not quite enough information here to answer your question. First of all – microwave oven transformers are designed to output several thousand volts to excite the magnetron in the oven – usually at around 1000W. So I have to assume you have rewound the transformer secondary to output the voltage you want to go to your iron loop (your drawing seems to indicate that you have). I will also assume that you stripped off the high voltage winding – so it’s not going to be happily floating at 2000V or so while you’re heating up the loop. To get to that point – you must have some specs on the soldering gun loop you’re planning on using, and an idea of how many watts you want dumped into the mold. You will need to share that information with us – or any answer we offer will be based on pure guesswork.

EDIT - As an afterthought - I wondered if it might not be simpler to use a secondhand soldering gun as a transformer - that's really all they are after all - and just bypass the trigger switch with your relay(???)

 

[abuhafss]

There’s not quite enough information here to answer your question. First of all – microwave oven transformers are designed to output several thousand volts to excite the magnetron in the oven – usually at around 1000W. So I have to assume you have rewound the transformer secondary to output the voltage you want to go to your iron loop (your drawing seems to indicate that you have). I will also assume that you stripped off the high voltage winding – so it’s not going to be happily floating at 2000V or so while you’re heating up the loop. To get to that point – you must have some specs on the soldering gun loop you’re planning on using, and an idea of how many watts you want dumped into the mold. You will need to share that information with us – or any answer we offer will be based on pure guesswork.

EDIT - As an afterthought - I wondered if it might not be simpler to use a secondhand soldering gun as a transformer - that's really all they are after all - and just bypass the trigger switch with your relay(???)

I am sorry, I should have provided you more details.

My objective is to insert a PVC tube in a the (cold) mold. The heater should heat the mold to an ideal temperature to melt the tip of the PVC tube inside the mold (for a few seconds) and then the heater must switch off and the mold must be cooled down immediately by circulating water through the outer sleeve of the mold.

The mold is made with steel for experiment only. I inserted the tail of the mold in a 45w soldering iron as shown in the picture. My test was successful.

I plan to build a set-up in which I can use molds of various working sizes. I mean, the outer dimensions of the mold will remain the same only the hole diameters would vary to match various sizes of PVC tubes. The actual molds will be coated with chrome or nickle. And, if required, I can change the material of the mold to aluminum, copper or brass for better conductivity. The mold would be installed inside a cooling sleeve, which cover only the body of the mold (excluding the tail).

After testing the trial mold on a soldering iron, I planned to use a soldering gun which heats the tip more quickly.


Now, come to my proposed circuit....yes, you got my idea. The secondary is rewound to give 2-4V. And I plan to connect 4 such heater irons in parallel, which will operate simultaneously. I hope, the transformer can easily bear their load.

By the way, my questions are still un-answered

 

[KMoffett]

abuhafss,

Do you realize that you're spreading your many questions on "one" project over half a dozen different forums (at least the ones I'm aware of) and I don't know how many different threads, as if everyone knew what you are trying to accomplish. If you want to use several forums, you might want to start each thread with a link to one post, somewhere, the explained you real goal in all these posts...one that contained all you requirements and limitations. I've watched a lot of very helpful people in many forums floundering for details that you have places in other threads or forum.

Ken

 

[abuhafss]

Posting on many forums means the probability of getting more views/ideas. But, one thing I didn't do was to link all those forums to one place because, I had the misunderstanding that linking to other similar forums might be banned. Anyway, my re-typing or copy-pasting of my questions shouldn't have bothered anyone. Neither I am breaking the rules of the forum nor I am not forcing anyone to reply me.

 

[(*steve*)]

Yes, but it also explains why you seem to pay little attention to what you're told.

 

[KMoffett]

It's mostly a lack of information. I see you having to answer or elaborate on the same issues over and over again. You mentioned in one post that you wanted the project to be under $50, but without this info people are proposing solutions that cost hundreds. You said that this was not commercial, but you wanted the temp display to be viewed form a control room. I guess my feeling that you waste peoples efforts if you withhold key information. I solve technical problems for a living, and makes me very suspicious when a customer can't clearly spec their needs. Then some people just cast a wide net in hopes they'll take advantage of others' efforts.

Ken

 

[abuhafss]

It's mostly a lack of information. I see you having to answer or elaborate on the same issues over and over again. You mentioned in one post that you wanted the project to be under $50, but without this info people are proposing solutions that cost hundreds. You said that this was not commercial, but you wanted the temp display to be viewed form a control room. I guess my feeling that you waste peoples efforts if you withhold key information. I solve technical problems for a living, and makes me very suspicious when a customer can't clearly spec their needs. Then some people just cast a wide net in hopes they'll take advantage of others' efforts.

Ken

I am working on the different stages of the project. I promise you guys, I will definitely show you the complete set-up in working order (with special thanks to all the fellows you helped me) to prove you that I am not wasting my time or others.

 

[(*steve*)]

If I had figured out earlier that you were posting multiple questions all about the same project I would have considered combining all of your threads into one. That way we have a bigger picture. However it's way too late for that now.

At present you may have different people all answering different parts of your big question without any awareness of what other people are saying or of the impact it might have on your other problems.

I have absolutely no problem with you asking for help in multiple places, but if you have multiple threads here, you probably have multiple threads elsewhere. That means you have even more people in the same boat. Whilst none of us mind helping you (that's why we're here) we don't want to be wasting our time.

You compound this by saying "my experts tell me...", presumably meaning people on other forums. If you could just be a little more honest and provide a link to that advice we may be able (if we're still motivated enough) to have a look at the advice and determine why it was given, possibly adding to it or clarifying it. Instead you just use it to refute our advice. Are you using our advice to refute theirs in their forums?