Hot-air rework stations that don't run their heaters at mains voltage?  - Page 1
Forum section: electronics / general

author: julian1
author_rank: Frequent Contributor
timestamp: July 16, 2016, 02:37:38 am
content: Eg. something transformer based, and priced appropriately for a simple hobbyest capable model?

author: Monkeh
author_rank: Super Contributor
timestamp: July 16, 2016, 02:42:41 am
content: Quote from: julian1 on July 16, 2016, 02:37:38 amThey all run their heaters at mains voltage. Why wouldn't they? The current's already substantial enough at 240V, you'd need some pretty thick wire at 24V.

author: amyk
author_rank: Super Contributor
timestamp: July 16, 2016, 03:09:07 pm
content: Why? Even hair dryers need to use mains heaters.Apart from the even higher current Monkeh already mentioned, it would also mean averylarge, heavy, and expensive transformer. 600-700W is typical, and at 240V that's around 2.5-3A, those in 120V countries will be consuming 5-6A.This is what a 1kVA transformer costs and looks like - it also weighs 14.2kg:http://uk.farnell.com/schneider-electric/abl6ts100b/transformer-1kva-1-x-24v/dp/2070206(Google apparently thinks "voltage" is the same as "wattage" if you try looking for specs on hot air rework stations.)

author: GEuser
author_rank: Frequent Contributor
timestamp: July 17, 2016, 12:45:45 am
content: As above^^ , power equals watts equals current = HOT .

author: zapta
author_rank: Super Contributor
timestamp: July 17, 2016, 03:07:07 am
content: Quote from: julian1 on July 16, 2016, 02:37:38 amExplaining the motivation for your question will help you getting useful answers.What do you want to achieve that you can't with a mains heater?

author: julian1
author_rank: Frequent Contributor
timestamp: July 17, 2016, 06:03:40 am
content: Quote from: zapta on July 17, 2016, 03:07:07 amI don't much like the idea of 700 watts at mains voltage and 400DegC temperature with only a few bits of plastic and pressed steel as insulation. Note, also the thread about the (Atten?) 858d with faulty Earth wiring.In a similar vein, I prefer a soldering iron using a step-down isolation transformer to 24 volts - rather than the cheap models that plug straight into the wall socket.I accept there are strong economical reasons why a rework station using a transformer or SMPS is not available given the rated power needed - and that would explain why I have not seen any available on the market.So my question was more digging - and to find out if anyone was aware of any exceptions.

author: PChi
author_rank: Frequent Contributor
timestamp: July 17, 2016, 09:20:29 am
content: For the OKI models (and others no doubt) the fan and heater are in a box and the handpiece is isolated because it is only connected via a tube carrying the hot air.I can understand your objection to mains power if the fan and heater are in the handpiece.

author: Monkeh
author_rank: Super Contributor
timestamp: July 17, 2016, 12:33:23 pm
content: Quote from: julian1 on July 17, 2016, 06:03:40 amNot a fan of hairdryers or hot air guns either I take it.

author: zapta
author_rank: Super Contributor
timestamp: July 17, 2016, 02:14:42 pm
content: Quote from: julian1 on July 17, 2016, 06:03:40 amIf your concern is safety, I suggest to get a unit from a known brand, preferably with safety mark such as UL.The atten style units are compact, inexpensive, and work well but I don't trust their safety (e.g. the ground path). This is why I returned the one I got and got a used Hakko 850 on ebay. Construction is better and it has UL certification.

author: KL27x
author_rank: Super Contributor
timestamp: July 19, 2016, 02:08:30 am
content: Unless you're comparably conductive as a few ohms of resistance wire, you got not much to fear.. well, burning yourself is plenty enough. Even if the heating element breaks, the plastic housing is good for 120V. If it don't work, stop using it. This isn't Brazil. If it wasn't safe, I wouldn't be able to buy it. Heck, I can't import a 6 mW laser.You know what scares me? Cheap extension cords. If the insulation breaks, you can be the resistance wire. Or they can start a fire. Anything passing 500+ watts, I know the electricity doesn't care about me so much, unless I'm soaking wet and standing on concrete. Scariest? Christmas lights. I hate em. GF loves em. 100's of feet of stupid thin wire plugged into mains.

author: helius
author_rank: Super Contributor
timestamp: July 19, 2016, 03:35:37 am
content: The Hakko FM-2029 has a 24V handpiece. Similar models are available from Pace (TJ-70 or TJ-85) and Zephyrtronics.

author: SteveyG
author_rank: Unknown
timestamp: July 19, 2016, 11:29:04 am
content: Quote from: KL27x on July 19, 2016, 02:08:30 amUnless you're having trouble expressing your comment, you don't really appear to understand electricity.

author: Monkeh
author_rank: Super Contributor
timestamp: July 19, 2016, 11:34:11 am
content: Quote from: helius on July 19, 2016, 03:35:37 amBeware that these are very low power and will not succeed at reflowing parts on a multilayer board at any useful speed.

author: wraper
author_rank: Unknown
timestamp: July 19, 2016, 11:49:39 am
content: Quote from: Monkeh on July 19, 2016, 11:34:11 amYeah, I wonder who uses them. When I've gone from 500W to 1000W hot air that was a huge upgrade. Cannot imagine using 140W hot air station.

author: Monkeh
author_rank: Super Contributor
timestamp: July 19, 2016, 11:52:48 am
content: Quote from: wraper on July 19, 2016, 11:49:39 amAbout the only purpose I can come up with is very careful rework of very small parts on sensitive boards - RF stuff maybe? There's little chance you'd get anything bigger than an 0402 off my laptop with one.

author: zapta
author_rank: Super Contributor
timestamp: July 20, 2016, 05:55:21 am
content: Quote from: wraper on July 19, 2016, 11:49:39 amThere a thread here about the Metal got air pencil.https://www.eevblog.com/forum/reviews/new-metcal-hct2-120-hot-air-pencil/Less power but more accurate control.

author: wraper
author_rank: Unknown
timestamp: July 20, 2016, 06:45:57 am
content: Quote from: zapta on July 20, 2016, 05:55:21 amDunno if there is a tiny bit more of control, I can set mine to 1-120 l/min airflow and put a nozzle of any thickness I want (there a 3 by default, but I never found a need to buy thinner one). The only thing I can imagine is that you can stick it in the crowded space between the tall parts because it is thin.

author: zapta
author_rank: Super Contributor
timestamp: July 21, 2016, 04:39:41 pm
content: Quote from: wraper on July 20, 2016, 06:45:57 amIt's smaller and easier to control while holding in your hand. Similar to a metcal handpiece vs a bulky solder iron. Better ergonomic.

author: KL27x
author_rank: Super Contributor
timestamp: July 21, 2016, 07:31:40 pm
content: QuoteYou're right, I made some factual/analogy error, there. But high power usage does not make device more dangerous or more need of electrical shielding. Every device powered from mains needs the same safety. 15W glue gun, 10W soldering iron. No different than big watt rework station. If you touch hot side, you are same (other than maybe higher power device while on has better chance of tripping breaker before you are elecuted, lol). No different than an extension cord. Maybe that is more acceptable/accurate? Thin insulation on Xmas lights bothers me, yes, for physical integrity.Thank you for pointing out my error?!

author: blacksheeplogic
author_rank: Frequent Contributor
timestamp: July 21, 2016, 09:36:38 pm
content: Quote from: PChi on July 17, 2016, 09:20:29 amThe fan is in the base unit. The heater is still in the hand piece.