CaptainStoner Posted January 1, 2009 Share Posted January 1, 2009 I just want to echo the sentiments above. I'm good with electronics but have never actually done any real practical mains electronics.. We studied power electrics and various motors/control gear, etc theory, on a whiteboard at college (city & guilds 2240 to level 3 and 2360 to level 2) but it's a long time ago and i'm a bit shaky on it all as I really need to do practical for theory to click mentally. My real experience comes with low voltage DC stuff.. But I bought a 230vac mains fan for my grow, super bargain from local family run electronics shop.. Tis only a small grow mine so this beefy (and it is a BLOODY beefy, cast alloy body, high pressure one) axial type should be fine.. cept its too damn noisy so i'm going to build up either a straight variac speed control (0.7a maplin) or a basic one stat, one variac controller as mentioned above.. If the fan is not enough, i can then at least still use my circuitry to control a proper item and i've only spent £4 on a fan which I can use elsewhere.. teehee I also have another one, spare, i was going to use in a repair job on the house but it was too bloody loud and didn't quite fit so i just bought a new xpelair. Back in the day with PC type pansy ass 12vdc axial fans we used to put a spacer between two and get them working together to both pull through really restrictive radiators, etc... Could always do that with 2 of these fans i have and slow them down a tad.. anyway, ta to all you guys, knew what variacs did but needed a few bits of wiring diagrams to base my designs on and a few questions answered. I need to get very much more stoned and re-read this thread & do some googling at a later stage, then i shall have a full design worked out, and very shortly, a controlled fan on my extract. Intake fans are already sorted, they are the beefiest of 12vdc 120x120x38mm pc fans, which move serious air, on little LM317T speed controls.. working on building a small 'stat into that circuit... Link to comment Share on other sites More sharing options...
Guest Krypt Posted March 24, 2009 Share Posted March 24, 2009 Can anyone confirm that this will work with a rvk250 and not make humming ? can anyone make me a list of the items ill need, cable and tools ect thanks B) http://www.maplin.co.uk/module.aspx?moduleno=6476 0.75A Variable Transformer Product Features * A robust, open style, variable auto-transformer which enables a AC 250 V 50Hz voltage supply to be varied between AC 0 and 270 V * Ideal for testing over and under-voltage operation of mains equipment, as the range 240V ±10% can be covered * Can be used for reducing AC voltages for testing continental equipment, and as lighting controllers for stage use * Specifically designed for panel mounting The device features a smooth operation with single layer non-saturating windings and a toroidal iron core. It also features 0 to 100% and 0 to 110% range that can be hard-wired depending on which is required. Please note that this unit has exposed live parts and must therefore be used in a suitable enclosure and is only suitable for connection to an AC 250 V 50Hz supply. Technical Specification 075A Version Terminal: Connection: AC 0 to 240V operation 1: Input & output negative 2: Input positive AC 240 V 3: Output positive AC 0 to 240 V AC 0 to 270 V operation 1: Input & output negative 4: Input positive AC 240 V 3: Output positive AC 0 to 270 V Dimensions: 90(h) x 84(dia.) x 97(l) mm 2 x 4mm holes on 28mm PCD, 8mm hole for shaft Link to comment Share on other sites More sharing options...
Joint hogger Posted March 24, 2009 Share Posted March 24, 2009 if you read through Rastajedis & danlads thread here theyll tell you everything you need to put 1 together. Link to comment Share on other sites More sharing options...
growguy yorks Posted March 24, 2009 Share Posted March 24, 2009 (edited) I'm working on a twin speed, ONE variac controller . Instead of the second variac I welded wires to a few specific voltages on the coil (check with V meter, a fan has specific optimal operating voltages) and connected those to a 3-way switch through which I select the voltage. Now I have the choice form 3 high speeds, and a constant variable low speed. With one more relay and switch added you can even define a seperate low speed for lights off for example. A switch is much cheaper than a variac. Hi there Whazzup... how are you.. This idea of soldering some wires on the variacs coil at specific voltages has me intrigued... Ive been thinking of using another ATC-800 temp controller, and using both the cooling and heating relays for cooling, Im thinking that would give me 3 speeds that the ATc could select from, ie when the temp is at the set level it would be at medium, if the temp rises then the 1st cooling relay would switch to high speed-and back when it dropped agin,, but if the temp dropped below the preset ideal level- the second relay(the one which would normally be the heating relay) could drop the speed to low speed... I hope you get what I mean-im sure you will...anyway I had planned to do this with a 5 step transformer, but now im thinking i could do your idea of using a variac and having the wires soldered on at selected voltages in 2 places for the low speed, the medium speed.. and then use full power for the high speed setting. Will it be ok to have the variacs mounted isnide he box without the shaft for the selector knob going through the box, no knob attached so basically i dont use the knob at all What do you think? Edited March 24, 2009 by growguy yorks Link to comment Share on other sites More sharing options...
wizbot Posted June 4, 2009 Share Posted June 4, 2009 (edited) Thanks for the DIY hints. This section has been really helpful. Quick question if i may.Is this Variac ok to connect to a 6inch RVK? Cheers. Edited June 13, 2009 by VRG Link to comment Share on other sites More sharing options...
Joint hogger Posted June 4, 2009 Share Posted June 4, 2009 looks ideal wizbot but i'd edit your 2 posts & remove the pics, for security reasons, you can upload any pic direct to the site as long as its less than 350k size. Link to comment Share on other sites More sharing options...
wizbot Posted June 4, 2009 Share Posted June 4, 2009 Thanks for the info. I'd love to edit my posts but i really can't see the edit button.(do low posters have less features on this board?) I'm not new to forums at all only this 1. Link to comment Share on other sites More sharing options...
takeiteazy Posted August 31, 2009 Share Posted August 31, 2009 ok , now for the base, which consists of a four way plug outlet for the fans to connect to , three cable glands , one for mains in, the other for the thermostat, and the other for the 4way, i decided to put an inline 1amp fuse between the mains and the variacs to stop any overload, all the neutrals come together under 1 terminal, as does the earth from mains in and the 4way going to the fans, the live mains in connects to the 2 live in's on the variacs, the 2 variable outlets from each of the variacs connect to terminals 1 and 3 on the thermostat and terminal 2 is your live output to the fans..easy Rj Confused by this, why have you got 2 variacs with one output to a extension lead ???? Link to comment Share on other sites More sharing options...
scraglor Posted August 31, 2009 Share Posted August 31, 2009 three speed controller, hi, lo and lo lo Link to comment Share on other sites More sharing options...
Rastajedi Posted September 3, 2009 Author Share Posted September 3, 2009 ok , now for the base, which consists of a four way plug outlet for the fans to connect to , three cable glands , one for mains in, the other for the thermostat, and the other for the 4way, i decided to put an inline 1amp fuse between the mains and the variacs to stop any overload, all the neutrals come together under 1 terminal, as does the earth from mains in and the 4way going to the fans, the live mains in connects to the 2 live in's on the variacs, the 2 variable outlets from each of the variacs connect to terminals 1 and 3 on the thermostat and terminal 2 is your live output to the fans..easy Rj Confused by this, why have you got 2 variacs with one output to a extension lead ???? As scraglor said in his previous post, one variac controls the minimum output when temps are below the threshold and the other controls the maximum when the temps rise above it, the extension lead was used out of convenience rather than buying another socket Rj Link to comment Share on other sites More sharing options...
Rastajedi Posted September 29, 2009 Author Share Posted September 29, 2009 Just a Linky to Joint hoggers tidy build, future reference n all that Rj Link to comment Share on other sites More sharing options...
weed_G Posted March 5, 2010 Share Posted March 5, 2010 tbh i could have made it cheaper by using just one variac and having it switch to 240v on max , i would have also been able to use a small housing which would have saved a few quid, but since i cant be there 24 hrs it takes alot of the stress away knowing that the temps should be quite stable at lights on and off can someone explain why using 2 variacs is better or safer than 1 .. Link to comment Share on other sites More sharing options...
scraglor Posted March 6, 2010 Share Posted March 6, 2010 it's not necessarily, it just means you can have an extra speed setting, i.e low, medium and high Link to comment Share on other sites More sharing options...
rich0 Posted March 19, 2010 Share Posted March 19, 2010 I'm looking to do a very simple mains > variac > fan set up. I've got a 125mm/5" Ruck High Powered Version (365m3/hour), can someone recommend me the best variac for the job? Would the £34.99 0.75A Variable Transformer from Maplins be safe with that particular fan? Also is there a particular box that would be suitable to fit it to (preferably available at B&Q)? I'm also assuming I'd need to solder the wires onto that variac (just don't own a soldering iron myself so would need to borrow one in advance, hence the n00b question) I'm also assuming I'd need to buy some 'solder?' too? Very concerned over safety with doing this as I'm a 100% novice. I bought the Xpelair WAC6R and wired it up, but got tons of hum. I believe it's because the fan is a high powered version. You can see my amateur handy work HERE . Thanks in advance for any help! This thread has been very useful so far. Link to comment Share on other sites More sharing options...
Joint hogger Posted March 19, 2010 Share Posted March 19, 2010 rich0 you dont need to use a soldering iron, if you do go with the maplin 0.75A variac, all you need is 6.3mm female spade connectors also, heres some pics of a box im going to use for a single variac. Link to comment Share on other sites More sharing options...
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