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General => General Technical Chat => Topic started by: ftransform on December 25, 2012, 03:33:37 am

Title: Can't afford a variac
Post by: ftransform on December 25, 2012, 03:33:37 am
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. 
Title: Re: Can't afford a variac
Post by: houdini on December 25, 2012, 03:40:34 am
https://www.youtube.com/watch?v=O45ghB23hA0 (https://www.youtube.com/watch?v=O45ghB23hA0)
Like that? 
Title: Re: Can't afford a variac
Post by: Tony. on December 25, 2012, 09:10:48 am
Why do you want to run LEDs off mains?
It'll work but, it's dangerous.
Title: Re: Can't afford a variac
Post by: AndyC_772 on December 25, 2012, 12:27:42 pm
This isn't the 'best hijack' thread...  :-//
Title: Re: Can't afford a variac
Post by: tom66 on December 25, 2012, 01:21:16 pm
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.
Title: Can't afford a variac
Post by: IanB on December 25, 2012, 01:43:24 pm
You are missing April 1st by at least three months. Come back then (if you are still alive) and try the post again...
Title: Re: Can't afford a variac
Post by: houdini on December 25, 2012, 11:13:41 pm
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.
Title: Re: Can't afford a variac
Post by: ftransform on December 26, 2012, 01:09:17 am
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.

im running 40 leds so I need 160V

I 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.
Title: Re: Can't afford a variac
Post by: c4757p on December 26, 2012, 02:32:47 am
I 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.

Quote
strips of LED ... 440V ... safely

Please tell me you are joking.  |O
Title: Re: Can't afford a variac
Post by: houdini on December 26, 2012, 03:57:06 am
most of the time you can run a transformer backwards.  So if it was a step down it would now be a step up.
Title: Re: Can't afford a variac
Post by: jerry507 on December 26, 2012, 04:15:19 am
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.
Title: Re: Can't afford a variac
Post by: houdini on December 26, 2012, 04:22:47 am
you could also make a long string of parallel leds.
Title: Re: Can't afford a variac
Post by: ftransform on December 26, 2012, 04:41:44 am
I need it to regulate brightness though. Sometimes I wanna have mood lighting when the ladies are over  :-+
Title: Re: Can't afford a variac
Post by: SeanB on December 26, 2012, 04:43:21 am
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?
Title: Re: Can't afford a variac
Post by: ftransform on December 26, 2012, 07:47:19 am
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?

Chill I don't want to light my house on fire.
Title: Re: Can't afford a variac
Post by: Tony. on December 26, 2012, 07:57:29 am
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.
Title: Re: Can't afford a variac
Post by: IanB on December 26, 2012, 08:59:48 am
Don't feed the troll, people  ;)
Title: Re: Can't afford a variac
Post by: ftransform on December 26, 2012, 09:09:40 am
Don't feed the troll, people  ;)
how dare you?
Title: Re: Can't afford a variac
Post by: nixxon on December 26, 2012, 10:12:54 am
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.

im running 40 leds so I need 160V

I 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.

I 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 ;)
Title: Re: Can't afford a variac
Post by: ftransform on December 26, 2012, 10:32:30 am
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.

im running 40 leds so I need 160V

I 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.

I 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 ;)

Not really, its alot safer at high voltages. :-+
Title: Re: Can't afford a variac
Post by: Zero999 on December 26, 2012, 02:08:46 pm
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.
Title: Re: Can't afford a variac
Post by: peter.mitchell on December 26, 2012, 02:18:02 pm
how much power do these LEDs use? 20mA? 1A?
Title: Re: Can't afford a variac
Post by: lewis on December 26, 2012, 02:36:28 pm
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
Title: Re: Can't afford a variac
Post by: gszo123 on December 26, 2012, 03:34:13 pm
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 the fuse! You'll need at least a 63A type D circuit breaker to get over the LED inrush

Please 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!
Title: Re: Can't afford a variac
Post by: ftransform on December 26, 2012, 07:51:08 pm
link to multiplying variac?
Title: Re: Can't afford a variac
Post by: PA0PBZ on December 26, 2012, 08:38:40 pm
link to multiplying variac?
Not exactly what you asked for, but I think this is the result:

(http://phil.ipal.org/electric/variac/big-1.jpg)
Title: Re: Can't afford a variac
Post by: ftransform on December 26, 2012, 09:57:33 pm
link to multiplying variac?
Not exactly what you asked for, but I think this is the result:

(http://phil.ipal.org/electric/variac/big-1.jpg)

Do 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?
Title: Re: Can't afford a variac
Post by: tom66 on December 26, 2012, 10:03:01 pm
Yes, but remember to check the tyre pressure to ensure your variac is running economically!
Low tyre pressure can lead to poor efficiency.
Title: Re: Can't afford a variac
Post by: ftransform on December 26, 2012, 10:54:59 pm
How many PSI do you recommend for a wheel barrow tire???
Title: Re: Can't afford a variac
Post by: tom66 on December 26, 2012, 10:59:42 pm
How many PSI do you recommend for a wheel barrow tire???

Multiply your nominal mains voltage by the number of individual ridges on the tyre, divide by three, multiply by six and add two.
Title: Re: Can't afford a variac
Post by: nixxon on December 26, 2012, 11:54:00 pm
How many PSI do you recommend for a wheel barrow tire???

Please do not go any further with this joke thread. It is not that funny :bullshit:

Title: Re: Can't afford a variac
Post by: c4757p on December 27, 2012, 12:50:17 am
Ignore it then. ::) Nobody is making you read it...
Title: Re: Can't afford a variac
Post by: ftransform on December 27, 2012, 02:59:36 am
How many PSI do you recommend for a wheel barrow tire???

Please do not go any further with this joke thread. It is not that funny :bullshit:
go 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?
Title: Re: Can't afford a variac
Post by: David_AVD on December 27, 2012, 03:23:32 am
Hopefully newbies will realise this thread has been one big piss-take.   :)
Title: Re: Can't afford a variac
Post by: c4757p on December 27, 2012, 04:46:18 am
A good one too, it got me... Took me a minute to realize what was going on  ::)
Title: Re: Can't afford a variac
Post by: David_AVD on December 27, 2012, 07:24:44 am
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.   :o
Title: Re: Can't afford a variac
Post by: Tony. on December 27, 2012, 08:12:14 am
How many PSI do you recommend for a wheel barrow tire???

Please do not go any further with this joke thread. It is not that funny :bullshit:
go 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?

(http://i.imgur.com/aK31A.gif)
Title: Re: Can't afford a variac
Post by: nixxon on December 27, 2012, 09:08:21 am
Hopefully newbies will realise this thread has been one big piss-take.   :)

pisstake
A 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 piss
by Doctor Whom Nov 15, 2005

Or maybe:

rip the piss   
to 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 off
by pagal_koota Apr 10, 2006
Title: Re: Can't afford a variac
Post by: TMM on December 27, 2012, 03:47:02 pm
pfft variac? all you need is a 7805 :-DD
Title: Re: Can't afford a variac
Post by: SeanB on December 27, 2012, 04:14:04 pm
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.
Title: Re: Can't afford a variac
Post by: AndyC_772 on December 27, 2012, 04:20:09 pm
I hope you used lead free transistors  :scared:
Title: Re: Can't afford a variac
Post by: SeanB on December 27, 2012, 05:02:05 pm
No, just used to wind the copper wire around the leads and the case, then it would not have any added taste.......
Title: Re: Can't afford a variac
Post by: ftransform on December 27, 2012, 05:26:46 pm
Whoa relax. I don't know what a transistor is. Can we stick to nichrome wire (like my daddy used to do it) :-+
Title: Re: Can't afford a variac
Post by: tom66 on December 27, 2012, 05:44:23 pm
I hope you used lead free transistors  :scared:

You mean wireless ones?
Title: Re: Can't afford a variac
Post by: ftransform on December 27, 2012, 05:45:11 pm
I DEFIANTLY DO NOT WANT WIRELESS IN THIS PROJECT OMFG
Title: Re: Can't afford a variac
Post by: ivan747 on December 27, 2012, 07:47:49 pm
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.
Title: Re: Can't afford a variac
Post by: ftransform on December 27, 2012, 08:52:35 pm
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.

yea i got a mig welder.  how many leds do you think i can run off one?
Title: Re: Can't afford a variac
Post by: lewis on December 27, 2012, 11:30:07 pm

yea i got a mig welder.  how many leds do you think i can run off one?

A mig welder is obviously only suitable for one LED. You will need one mig welder per LED. Read your Horowitz Hill!
Title: Re: Can't afford a variac
Post by: Jay_Diddy_B on December 27, 2012, 11:50:42 pm
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: :P

(http://i46.tinypic.com/5yzq83.jpg)

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 dimmers
3) They work from AC or DC
4) They can work at higher temperatures than LED and CCFL bulbs
5) 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
Title: Re: Can't afford a variac
Post by: c4757p on December 28, 2012, 12:20:51 am
5) The heat that is generated by them is not waste, it contributes to keeping us warm in winter.

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 is free. 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.
Title: Re: Can't afford a variac
Post by: ftransform on December 28, 2012, 04:49:39 am
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.
Title: Re: Can't afford a variac
Post by: c4757p on December 28, 2012, 04:59:23 am
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 spill non-burning naphtha you can clean that shit right up by just lighting it right there on the floor.
Title: Re: Can't afford a variac
Post by: peter.mitchell on December 28, 2012, 05:37:39 am
We live in a forest, where the wood is free. We still haven't found an electricity tree, so we pay for that.

bullcrud, i've seen heaps of videos on the innernets about how to get electricity from all kinds of things, lemons, beer, even free electricity from some newfangled machines.
Title: Re: Can't afford a variac
Post by: c4757p on December 28, 2012, 05:43:26 am
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.
Title: Re: Can't afford a variac
Post by: ftransform on December 28, 2012, 05:50:18 am
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 spill non-burning naphtha you can clean that shit right up by just lighting it right there on the floor.

if you ignite your furniture it will potentially destroy the concrete.  :--
Title: Re: Can't afford a variac
Post by: c4757p on December 28, 2012, 06:07:05 am
As usual, weird, artsy types have a weird, artsy http://www.designboom.com/design/contemporary-concrete-furniture/ (http://[url=http://www.designboom.com/design/contemporary-concrete-furniture/)]solution[/url] to your problem.
Title: Re: Can't afford a variac
Post by: ftransform on December 28, 2012, 03:39:52 pm
As usual, weird, artsy types have a weird, artsy http://www.designboom.com/design/contemporary-concrete-furniture/ (http://[url=http://www.designboom.com/design/contemporary-concrete-furniture/)]solution[/url] to your problem.
I like the sound of this. It's kind of uncomfortable though.
Title: Re: Can't afford a variac
Post by: G7PSK on December 28, 2012, 04:08:32 pm

[/quote]

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 is free. 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.


[/quote]

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.
Title: Re: Can't afford a variac
Post by: c4757p on December 28, 2012, 04:12:45 pm
 :-DD
Title: Re: Can't afford a variac
Post by: ftransform on December 28, 2012, 04:25:54 pm
Thats how we make toast in the morning. Just climb up on those trees with a loaf of bread. Easy and cheap. :-+