Can't afford a variac - Page 1
Forum section: electronics / general

author: ftransform
author_rank: Frequent Contributor
timestamp: December 25, 2012, 03:33:37 am
content: Ok so the plan is to connect a large carbon rod across the outlet and turn it into a voltage divider using alligator clips.Anyone have suggestions?I need it to run LED lights. Don't worry about the heat issue, I'm going to lay it on a tile with bricks and a house fan for cooling. Or maybe I will throw it into a tub of distilled water, or oil if it conducts too much electricity.

author: houdini
author_rank: Regular Contributor
timestamp: December 25, 2012, 03:40:34 am
content: Like that?

author: Tony.
author_rank: Newbie
timestamp: December 25, 2012, 09:10:48 am
content: Why do you want to run LEDs off mains?It'll work but, it's dangerous.

author: AndyC_772
author_rank: Super Contributor
timestamp: December 25, 2012, 12:27:42 pm
content: This isn't the 'best hijack' thread...

author: tom66
author_rank: Super Contributor
timestamp: December 25, 2012, 01:21:16 pm
content: I picked up two 4000VA variacs on eBay for £50 because they were nearby. Sold one for £153 (offered a courier service), kept the other.

author: IanB
author_rank: Super Contributor
timestamp: December 25, 2012, 01:43:24 pm
content: You are missing April 1st by at least three months. Come back then (if you are still alive) and try the post again...

author: houdini
author_rank: Regular Contributor
timestamp: December 25, 2012, 11:13:41 pm
content: on a more practical note you dont need a variac to light leds. Just use the transformer from a vcr or something just make sure its the voltage you need.

author: ftransform
author_rank: Frequent Contributor
timestamp: December 26, 2012, 01:09:17 am
content: Quote from: houdini on December 25, 2012, 11:13:41 pmim running 40 leds so I need 160VI was thinking about running longer strips of LED but I need to talk to the power company about installing 440V power in my house so I can do that safely.

author: c4757p
author_rank: Super Contributor
timestamp: December 26, 2012, 02:32:47 am
content: Quote from: ftransform on December 26, 2012, 01:09:17 amQuotePleasetell me you are joking.

author: houdini
author_rank: Regular Contributor
timestamp: December 26, 2012, 03:57:06 am
content: most of the time you can run a transformer backwards. So if it was a step down it would now be a step up.

author: jerry507
author_rank: Regular Contributor
timestamp: December 26, 2012, 04:15:19 am
content: Ignoring the knee jerk reactions from most of the other posters, you might have trouble getting 160V out of a variac. I think mine does 140V? Obviously it'd be dependent on model but if you're broke then you'll probably be looking at older ones. You might not really have any cheap options here.

author: houdini
author_rank: Regular Contributor
timestamp: December 26, 2012, 04:22:47 am
content: you could also make a long string of parallel leds.

author: ftransform
author_rank: Frequent Contributor
timestamp: December 26, 2012, 04:41:44 am
content: I need it to regulate brightness though. Sometimes I wanna have mood lighting when the ladies are over

author: SeanB
author_rank: Super Contributor
timestamp: December 26, 2012, 04:43:21 am
content: I have no problem getting 160V out of my variac, it goes to 340V output. Then again I live in a 220V country.If you want variable brightness why not use a phase control dimmer?

author: ftransform
author_rank: Frequent Contributor
timestamp: December 26, 2012, 07:47:19 am
content: Quote from: SeanB on December 26, 2012, 04:43:21 amChill I don't want to light my house on fire.

author: Tony.
author_rank: Newbie
timestamp: December 26, 2012, 07:57:29 am
content: Erm, so you would buy a variac just to use it as a dimmer for interior lighting?But if you were compelled, a light switch dimmer from the hardware store and full wave rectification would be one way to do it.Just hop on eBay and buy a few meters of some 5050 smd LED strip and do it properly.

author: IanB
author_rank: Super Contributor
timestamp: December 26, 2012, 08:59:48 am
content: Don't feed the troll, people

author: ftransform
author_rank: Frequent Contributor
timestamp: December 26, 2012, 09:09:40 am
content: Quote from: IanB on December 26, 2012, 08:59:48 amhow dare you?

author: nixxon
author_rank: Frequent Contributor
timestamp: December 26, 2012, 10:12:54 am
content: Quote from: ftransform on December 26, 2012, 01:09:17 amI talked to my power Company, and they installed 4.4 kV just so I could run some really long LEDs. In serial, of course. Parallell connections are for whimps

author: ftransform
author_rank: Frequent Contributor
timestamp: December 26, 2012, 10:32:30 am
content: Quote from: nixxon on December 26, 2012, 10:12:54 amNot really, its alot safer at high voltages.

author: Zero999
author_rank: Super Contributor
timestamp: December 26, 2012, 02:08:46 pm
content: Lol, is this thread serious?Why do you need a variac? How about using a diode & capacitor voltage doubler to run a long LED string? If you select the correct capacitor values, the LED current will be safely limited.

author: peter.mitchell
author_rank: Super Contributor
timestamp: December 26, 2012, 02:18:02 pm
content: how much power do these LEDs use? 20mA? 1A?

author: lewis
author_rank: Frequent Contributor
timestamp: December 26, 2012, 02:36:28 pm
content: If you're going to use a variac, make sure you use a DC variac. The AC ones hum a bit and you don't want any hums in the living room when the ladies are about.Also, don't forget to change the fuse! You'll need at least a 63A type D circuit breaker to get over the LED inrush

author: gszo123
author_rank: Contributor
timestamp: December 26, 2012, 03:34:13 pm
content: Quote from: lewis on December 26, 2012, 02:36:28 pmPlease consider buying a multiplying DC variac. You can safely multiply your voltage to say 1000V, use 480V to power your LED strips and sell rest of the voltage to energy grid. You'll reimburse costs of your variac in no time!

author: ftransform
author_rank: Frequent Contributor
timestamp: December 26, 2012, 07:51:08 pm
content: link to multiplying variac?

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 26, 2012, 08:38:40 pm
content: Quote from: ftransform on December 26, 2012, 07:51:08 pmNot exactly what you asked for, but I think this is the result:

author: ftransform
author_rank: Frequent Contributor
timestamp: December 26, 2012, 09:57:33 pm
content: Quote from: PA0PBZ on December 26, 2012, 08:38:40 pmDo you think I can wind one out of that electrical cord you can find in peoples homes?Can I wind that shit around a tire to make those doughnuts?make I can use the tires for like a scooter or something so their similar size?

author: tom66
author_rank: Super Contributor
timestamp: December 26, 2012, 10:03:01 pm
content: Yes, but remember to check the tyre pressure to ensure your variac is running economically!Low tyre pressure can lead to poor efficiency.

author: ftransform
author_rank: Frequent Contributor
timestamp: December 26, 2012, 10:54:59 pm
content: How many PSI do you recommend for a wheel barrow tire???

author: tom66
author_rank: Super Contributor
timestamp: December 26, 2012, 10:59:42 pm
content: Quote from: ftransform on December 26, 2012, 10:54:59 pmMultiply your nominal mains voltage by the number of individual ridges on the tyre, divide by three, multiply by six and add two.

author: nixxon
author_rank: Frequent Contributor
timestamp: December 26, 2012, 11:54:00 pm
content: Quote from: ftransform on December 26, 2012, 10:54:59 pmPlease do not go any further with this joke thread. It is not that funny

author: c4757p
author_rank: Super Contributor
timestamp: December 27, 2012, 12:50:17 am
content: Ignore it then.Nobody is making you read it...

author: ftransform
author_rank: Frequent Contributor
timestamp: December 27, 2012, 02:59:36 am
content: Quote from: nixxon on December 26, 2012, 11:54:00 pmgo away just because I don't like doing things the same way everyone else does (I don't wanna burn down my house with some chinese startrek "phase inverter." Seriously that sounds like something out of a startrek episode do you really blame me for not wanting that in my house? I'd rather make my own electronics with stuff I have laying around, reliable designs I can trust to keep me safe.Anyway I'm gonna see where I can source those wheelbarrow tires, whats the minimum amount you need to make a multiplication transformer??9?And how important is it that their all the same type?

author: David_AVD
author_rank: Super Contributor
timestamp: December 27, 2012, 03:23:32 am
content: Hopefully newbies will realise this thread has been one big piss-take.

author: c4757p
author_rank: Super Contributor
timestamp: December 27, 2012, 04:46:18 am
content: A good one too, it got me... Took me a minute to realize what was going on

author: David_AVD
author_rank: Super Contributor
timestamp: December 27, 2012, 07:24:44 am
content: It can be hard to tell sometimes. I've seen threads where I was sure it was a joke but the OP was completely serious.

author: Tony.
author_rank: Newbie
timestamp: December 27, 2012, 08:12:14 am
content: Quote from: ftransform on December 27, 2012, 02:59:36 am

author: nixxon
author_rank: Frequent Contributor
timestamp: December 27, 2012, 09:08:21 am
content: Quote from: David_AVD on December 27, 2012, 03:23:32 ampisstakeA satire, parody, or mockery."Look at this scary fundamentalist Web site. I can't believe that anyone would say such things and mean them." "They don't. It's obviously a pisstake."satire parody irony take the piss taking the pissby Doctor Whom Nov 15, 2005Or maybe:rip the pissto rip the piss is to point fun at someone, slag them off, take the mickey or generally have a laugh at the expense of someone else.Aye Kenny is such a wank, I'm gonna rip the piss right out him.take the piss take the mickey rip-the-piss extract the michael slag offby pagal_koota Apr 10, 2006

author: TMM
author_rank: Frequent Contributor
timestamp: December 27, 2012, 03:47:02 pm
content: pfft variac? all you need is a 7805

author: SeanB
author_rank: Super Contributor
timestamp: December 27, 2012, 04:14:04 pm
content: I have run power transistors in a glass of water as a quick and simple heatsink method, and if you put in a teabag you can make a nice brew as well.

author: AndyC_772
author_rank: Super Contributor
timestamp: December 27, 2012, 04:20:09 pm
content: I hope you used lead free transistors

author: SeanB
author_rank: Super Contributor
timestamp: December 27, 2012, 05:02:05 pm
content: No, just used to wind the copper wire around the leads and the case, then it would not have any added taste.......

author: ftransform
author_rank: Frequent Contributor
timestamp: December 27, 2012, 05:26:46 pm
content: Whoa relax. I don't know what a transistor is. Can we stick to nichrome wire (like my daddy used to do it)

author: tom66
author_rank: Super Contributor
timestamp: December 27, 2012, 05:44:23 pm
content: Quote from: AndyC_772 on December 27, 2012, 04:20:09 pmYou mean wireless ones?

author: ftransform
author_rank: Frequent Contributor
timestamp: December 27, 2012, 05:45:11 pm
content: I DEFIANTLY DO NOT WANT WIRELESS IN THIS PROJECT OMFG

author: ivan747
author_rank: Super Contributor
timestamp: December 27, 2012, 07:47:49 pm
content: Do you have access to a spot welder? I'm sure you can light a lot of parallel LEDs with one of those. Just make sure you get the circuit breakers out of the fuse box and use solid coper wires instead.

author: ftransform
author_rank: Frequent Contributor
timestamp: December 27, 2012, 08:52:35 pm
content: Quote from: ivan747 on December 27, 2012, 07:47:49 pmyea i got a mig welder. how many leds do you think i can run off one?

author: lewis
author_rank: Frequent Contributor
timestamp: December 27, 2012, 11:30:07 pm
content: Quote from: ftransform on December 27, 2012, 08:52:35 pmA mig welder is obviously only suitable for one LED. You will need one mig welder per LED. Read your Horowitz Hill!

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: December 27, 2012, 11:50:42 pm
content: Hi,This for the original poster.Have you thought about using a thin tungsten wire, in a vacuum, inside a glass envelope?Something like this:I understand that these devices have been around for over a hundred years.I also heard that:1) These devices don't make nasty interference.2) They can be dimmed easily with TRIAC dimmers3) They work from AC or DC4) They can work at higher temperatures than LED and CCFL bulbs5) The heat that is generated by them is not waste, it contributes to keeping us warm in winter.I think that the LED is new fangled gadget that won't catch on.Jay_Diddy_B

author: c4757p
author_rank: Super Contributor
timestamp: December 28, 2012, 12:20:51 am
content: Quote from: Jay_Diddy_B on December 27, 2012, 11:50:42 pmI beg to differ. A large portion of the world lives in places where heating is often unnecessary. Additionally, my house is mainly heated with a wood fire. We live in a forest, where the wood isfree. We still haven't found an electricity tree, so we pay for that. The light bulb's waste heat may well contribute to warming the house, but with additional cost. This arrangement is not unusual in many places.In short, I'd like the cost to go where I choose. If I hang a light bulb, I want it to do as little more besides emitting light as possible. If I need heat as well, I'll find a way to get it, but I want it separate from my light.

author: ftransform
author_rank: Frequent Contributor
timestamp: December 28, 2012, 04:49:39 am
content: I usually use naphta in my house. Little bowls of naphta burning are pretty good light sources but you need to be careful not to tip them over or you can burn your house down.

author: c4757p
author_rank: Super Contributor
timestamp: December 28, 2012, 04:59:23 am
content: That's why you build your house out of concrete, no paint or anything. You can spill all the burning naphtha you want - hell, if you spillnon-burning naphtha you can clean that shit right up by just lighting it right there on the floor.

author: peter.mitchell
author_rank: Super Contributor
timestamp: December 28, 2012, 05:37:39 am
content: Quote from: c4757p on December 28, 2012, 12:20:51 ambullcrud, i've seenheapsof videos on theinnernetsabout how to get electricity from all kinds of things, lemons, beer,even freeelectricity from some newfangled machines.

author: c4757p
author_rank: Super Contributor
timestamp: December 28, 2012, 05:43:26 am
content: Damn, I've got to find those! I've got more lemons here in upstate New York than I could poke a stick at*!*That's because there's two feet of snow outside and I don't want to go trekking through it to grab a poking-stick.

author: ftransform
author_rank: Frequent Contributor
timestamp: December 28, 2012, 05:50:18 am
content: Quote from: c4757p on December 28, 2012, 04:59:23 amif you ignite your furniture it will potentially destroy the concrete.

author: c4757p
author_rank: Super Contributor
timestamp: December 28, 2012, 06:07:05 am
content: As usual, weird, artsy types have a weird, artsyhttp://www.designboom.com/design/contemporary-concrete-furniture/]solution to your problem.

author: ftransform
author_rank: Frequent Contributor
timestamp: December 28, 2012, 03:39:52 pm
content: Quote from: c4757p on December 28, 2012, 06:07:05 amI like the sound of this. It's kind of uncomfortable though.

author: G7PSK
author_rank: Super Contributor
timestamp: December 28, 2012, 04:08:32 pm
content: I beg to differ. A large portion of the world lives in places where heating is often unnecessary. Additionally, my house is mainly heated with a wood fire. We live in a forest, where the wood isfree. We still haven't found an electricity tree, so we pay for that. The light bulb's waste heat may well contribute to warming the house, but with additional cost. This arrangement is not unusual in many places.The electricity trees are easy to find, they are always tall and straight with only one or two branches sticking straight out at the top they also always seem to be in a pretty straight line and tied together with string or wire or something hanging from the odd brown fruit on the ends of the branches.

author: ftransform
author_rank: Frequent Contributor
timestamp: December 28, 2012, 04:25:54 pm
content: Thats how we make toast in the morning. Just climb up on those trees with a loaf of bread. Easy and cheap.