How do I use a relay to switch a high current? - Page 1
Forum section: electronics / beginners

author: J.Xerneas
author_rank: Contributor
timestamp: December 27, 2015, 03:52:20 am
content: I want to build my own box mod for vaping but I don't want to use a mosfet because they are pricey. How can I wire a relay to do this instead? I have a 4 pin relay from a truck that is rated for 80 amps that I am going to use.

author: rx8pilot
author_rank: Super Contributor
timestamp: December 27, 2015, 06:42:04 am
content: MOSFET are expensive?You should provide much much more information if you expect any useful answers.Sent from my SAMSUNG-SM-G890A using Tapatalk

author: Psi
author_rank: Super Contributor
timestamp: December 27, 2015, 07:44:34 am
content: Relays are more expensive than mosfets.

author: Richard Crowley
author_rank: Super Contributor
timestamp: December 27, 2015, 07:48:39 am
content: Quote from: Psi on December 27, 2015, 07:44:34 amA relay in the hand is infinitely cheaper than anything you must purchase.OTOH vaping is little better than outright filthy smoking as a dubious pursuit.And @J.Xerneas will need a MOSFET or some other substantial transistor simply to drive his relay.

author: aaronwiz
author_rank: Contributor
timestamp: December 28, 2015, 01:53:12 am
content: Quote from: J.Xerneas on December 27, 2015, 03:52:20 amIf you must use a relay, you will probably need a a driver depending on what the relay is connected to. We really need more info about what it is that will be controlling the relay, and how much current the relay needs.If you are using a microcontroller and the relay isn't terribly large, you can probably get away using any npn TO-92 transistor such as the 2n3904 or 2n4401 to drive it.

author: Marco
author_rank: Super Contributor
timestamp: December 28, 2015, 02:15:45 am
content: Reconstructive surgery after the battery blows up in your face will also be pricey, although whether you use a MOSFET or relay doesn't really matter much in that regard.

author: doobedoobedo
author_rank: Regular Contributor
timestamp: December 28, 2015, 10:24:48 am
content: Quote from: J.Xerneas on December 27, 2015, 03:52:20 amUse a mosfet. I'd recommend this onehttp://www.irf.com/product-info/datasheets/data/irlb3034pbf.pdfit's 2quid from mouser. Use a fuse too the Raychem MHP-TA15-9-77 is excellent, resettable and tiny.Quote from: Richard Crowley on December 27, 2015, 07:48:39 amEducate yourself sirhttps://www.gov.uk/government/publications/e-cigarettes-an-evidence-update

author: Marco
author_rank: Super Contributor
timestamp: December 28, 2015, 03:09:53 pm
content: The sheer amount of liquid modders put into their lungs are not unlikely to have long term side effects separate from the presence/absence of carcinogens in my opinion, normal vaping isn't really comparable to using your lungs as an accumulator for a room filling smoke machine.

author: doobedoobedo
author_rank: Regular Contributor
timestamp: December 28, 2015, 07:03:12 pm
content: Quote from: Marco on December 28, 2015, 03:09:53 pmDo you have any evidence for your speculation?Also I don't think liquid goes into the lungs, I believe it's vapour, otherwise I'm sure someone would have drowned by now.

author: cponcsak
author_rank: Contributor
timestamp: December 29, 2015, 06:55:47 am
content: I'm sorry. At the risk of derailing the thread, I couldn't help it.

author: SeanB
author_rank: Super Contributor
timestamp: December 29, 2015, 07:14:22 am
content: Mist, a fine suspension of droplets in air. Google popcorn lung, and if you have safe search turned off do not look at the images.

author: Srbel
author_rank: Frequent Contributor
timestamp: December 29, 2015, 07:17:48 am
content: Polonium 210 from tobacco or cancerogenic substances from chemicals in e-cigars. What is better for inhaling?

author: SeanB
author_rank: Super Contributor
timestamp: December 29, 2015, 07:24:55 am
content: Quote from: Srbel on December 29, 2015, 07:17:48 amNeither, you will be better off breathing regular polluted air instead, no added junk.

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: December 29, 2015, 07:28:02 am
content: car relay handle high current but low voltage, don't use it over rated voltage.

author: mikerj
author_rank: Super Contributor
timestamp: December 29, 2015, 07:55:42 am
content: Quote from: SeanB on December 29, 2015, 07:14:22 amThere are alsoother possible consequencesfrom the lithium cells.

author: doobedoobedo
author_rank: Regular Contributor
timestamp: December 29, 2015, 12:54:47 pm
content: Thanks for all the quantifiable evidence people. You're really showing your science and engineering backgrounds.

author: cponcsak
author_rank: Contributor
timestamp: December 29, 2015, 04:31:31 pm
content: It wouldn't matter if people went out and posted the evidence you requested. There are mountains of evidence against smoking and people still do it and you'll continue to vape regardless of how much evidence anyone posts so its pointless. People not posting evidence has more to do with us not caring but whatever helps you sleep at night.

author: rx8pilot
author_rank: Super Contributor
timestamp: December 29, 2015, 06:22:37 pm
content: Quote from: doobedoobedo on December 29, 2015, 12:54:47 pmGathering and presenting evidence takes time. Time is valuable. I don't want to waste my time. Not wasting time is essentially the definition of efficiency. Engineers and scientists love efficiency. I think all the engineers here are being rather efficient by choosing not to bother with a thread that started out with an unanswerable question/problem followed by a discussion of the health effects of vaping.

author: Zero999
author_rank: Super Contributor
timestamp: December 29, 2015, 07:13:53 pm
content: Quote from: SeanB on December 29, 2015, 07:14:22 amHere's the study.http://www.hsph.harvard.edu/news/press-releases/e-cigarette-flavoring-chemicals-linked-to-respiratory-disease/It doesn't prove that ecigs are unsafe, just that 75% of the brands they tested contain chemicals which are linked to severe respiratory disease. How many recorded cases of popcorn lung have been directly linked to ecigs?In the case of real cigarettes, 100% of brands tested contain chemicals known to cause severe respiratory disease and hundreds of other series illnesses ranging from cancer to heart disease, with millions of cases are directly linked to smoking.Ecigs have the potential to be a very safe alternatives to tobacco. Legislation is necessary to ban the harmful chemicals found in the brands tested.

author: doobedoobedo
author_rank: Regular Contributor
timestamp: December 29, 2015, 07:35:56 pm
content: Quote from: cponcsak on December 29, 2015, 04:31:31 pmAh so. Posting bullshit OK. Asking bullshiiters to back it up, not OK. Thanks.Quote from: rx8pilot on December 29, 2015, 06:22:37 pmAnd there was me thinking that science was the pursuit of truth. And engineering the application of it. I stand corrected. From your definition Engineering seems to be "can't be arsed, just make shit up". I won't take your definition of science as you don't appear to know what it is.

author: rx8pilot
author_rank: Super Contributor
timestamp: December 29, 2015, 07:37:53 pm
content: I made no effort to define engineering or science.Sent from my SAMSUNG-SM-G890A using Tapatalk

author: doobedoobedo
author_rank: Regular Contributor
timestamp: December 29, 2015, 08:13:49 pm
content: Quote from: Hero999 on December 29, 2015, 07:13:53 pmYes DA and AP are a problem, they give a creamy, buttery taste which people like. Levels of those chemicals are much lower than in real cigarettes though. Here's a response to the Harvard study by someone who did a previous studyhttp://www.ecigarette-research.org/research/index.php/whats-new/whatsnew-2015/236-da2(previous study linked within the article).I'm in two minds as to whether they should be banned or that their presence and levels should be clearly labelled in order to allow in informed decision.

author: rx8pilot
author_rank: Super Contributor
timestamp: December 29, 2015, 09:23:17 pm
content: ..... there was something about MOSFETs and relays earlier.Sent from my SAMSUNG-SM-G890A using Tapatalk

author: Marco
author_rank: Super Contributor
timestamp: February 09, 2016, 02:17:08 pm
content: Quote from: J.Xerneas on February 09, 2016, 02:13:09 pm...

author: bitshift
author_rank: Regular Contributor
timestamp: February 09, 2016, 02:53:43 pm
content: Quote from: J.Xerneas on February 09, 2016, 02:13:09 pmFine, we shall step back and allow natural selection to take its course.

author: Muxr
author_rank: Super Contributor
timestamp: February 09, 2016, 03:08:40 pm
content: Quote from: doobedoobedo on December 28, 2015, 10:24:48 amGood suggestions. Yeah vaping is much better than smoking.

author: Zero999
author_rank: Super Contributor
timestamp: February 09, 2016, 03:54:59 pm
content: Quote from: J.Xerneas on December 27, 2015, 03:52:20 amPeople on the Internet have opinions on everything and you'll get them whether you like it or not.An automotive relay would certainly work but it's not necessarily the cheaper or best option.How much did the relay you found cost, compared to the MOSFET? As mentioned above, MOSFETs are generally cheaper than relays but it may not be the case for some overpriced suppliers.

author: Seekonk
author_rank: Super Contributor
timestamp: February 09, 2016, 04:37:46 pm
content: Here is more unwanted advice. E waste is everywhere. FREE relays and FETs. It is piling up in my basement and I can barely move. Even the surface mount crap. I take a grinder with a thin cutoff wheel and get the part I want, even comes pre mounted. Just don't see why people are buying stuff all the time. Old crap is everywhere. The world is your electronic oyster.