Let's Make Robots!

Soldering iron...

I recently bought this soldering iron-


It is of 35W and takes a few minutes to get warm but it takes a whole half an hour to cool down. Is it normal? Or am I just getting paranoid? Is it alright if it takes so much time to cool? I'm asking this as I've had virtually no experience with a soldering iron.
Also, it will be nice if someone can give me a link to making a cheap regulator to control the power of this iron.As of now, its a beast and it keeps on getting hot and hot (I've only had one run at it, so maybe I'm saying that because of lack of knowledge). I need a regulator to keep it calm.

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use a pair of heavy vice grips as a heat sink when required... http://www.irwin.com/tools/brands/vise-grip

I decided to risk soldering with that iron and I had a bad experience. I soldered one wire of a speaker into a radio's circuit. It started getting hot as soon as I plugged in the wire. It got hot enough to melt the solder in about 45 seconds and didn't stop there. The wire was a bit short so the switch kept on disconnecting which stopped it probably from melting itself. Still, there are black spots now on the edge of the iron and there was constant evolution of smoke (smoke not from solder but from the iron). The soldering job was done though (the joint is not neat but that was because of my inexperience rather than a problem of the iron). Later on, I unscrewed the iron to have a look inside. The iron is a simple one (or atleast it looks simple). Two wires run into it and are connected to a pair of hot plates. The hot plates get warm due to eddy currents formed in it (atleast, I think so). The other end of the tip is flat and is placed between the 2 heating plates and the tip eventually gets hot due to conduction. There are, or actually were, 2 pads of some insulating material to keep the body cool but now it's burnt and non existent which explains the reason why it was smoking and had the two black spot. Another thing I noticed was that while it took almost a minute to become hot enough to melt solder, it became cool to a temperature where no more solder melts in a few seconds (<10). So, now, my iron requires newer and better insulation and a regulator to supply current only till it gets hot to an ambient temperature.

@kariloy, sanc, thanks for removing doubts about cooling.

@mogul, thanks. Can you tell me what informations you need before you can tell its regulated or not?

@charge, thanks for the advise. I'm taking care of the tip as I have read pages from other people asking about how to take care of the tip. A Scrotch Brite is what I'm using. Making a inverter is not what I had in my mind (although that I might make one just for fun). I wanted to find out if its regulated so that it can maintain a temperature and how to make a regulator if its not regulated.

@chuck, sorry but I've already bought it and as it goes with me, I can't buy a new one till I completely destory this one. Even you'll agree with me that since it costs me 70 Cents, it was worth the money I spent on it. What will be better info right now will be info on how to keep the heat regulated.

An easy way to tell if it's regulated or not is to run it through a power meter. If it turns on and off repeatedly it's regulated.

the tip is probably as big as a transistor , i think this soldering iron is for metal work  pipe, led light and stuff, that's why it holds the heat. if you using this soldering iron for electronics  you will do more harm than good, unless your soldering very large cable Eg, car battery terminals , if you are planning on making robots you need a smaller iron.  

best case cheap

http://www.ebay.com.au/itm/ATTEN-SOLDERING-IRON-STATION-AT937b-50W-Lead-Free-ESD-SAFE-CE-RHOS-OZ-WRT-/270975165722?pt=AU_B_I_Electrical_Test_Equipment&hash=item3f1760e51a

basic cheap

http://www.ebay.com.au/itm/Pro-30W-Soldering-Iron-Kit-Solder-Stand-Sucker-bits-Electric-AU-plug-/190622280346?pt=AU_B_I_Electrical_Test_Equipment&hash=item2c61f92a9a

this the minim iron, find something of the same size   

http://www.sparkfun.com/products/9507

I had one like that one before.It got fiercely hot and lasted only a few weeks.The key here to to remember to keep the tip nice and clean after every soldering attempt.(Use scrotch brite pad to clean excess solder).Also u can extend its life by turning the power of as soon as it starts to melt some solder.At 35 watt it is one for heavy duty soldering.Next time u could get a 25 or 30 watt-more suited for general purpose electronics.If u r interested in making a soldering inverter u can check out this link: http://www.electronicsforu.com/electronicsforu/circuitarchives/view_article.asp?sno=116&article_type=1&title=Inverter%20for%20Soldering%20Iron&id=451&tt=unhot

The cool down time it self is not a problem. What should concern you more is if the tip is getting too hot. The iron looks rather crude, I could be afraid it's not regulated. If not, you will not have a constant soldering temperature, which again makes it hard to create beautiful solder joints. Soldering smaller semiconductors and IC's will be hard with an iron  like yours.

Also, you are going to hold it quite far from the tip, which means that you will shake to tip more than good is.

I have a 25 Watt soldering iron and it cools pretty fast (in like 10 minutes). Your's maybe taking longer time because it is of more wattage, just a guess though.

Not that I know much on the subject, but the only concern you should have regarding cool-down time I think is knowing when it's safe to store it away. Also you should have a stand to put it on while you're soldering. Always holding it while you solder seems quite unfeasible (from my limited experience) and putting it down on a surface, well I guess I won't have to tell you what that might do... :P