Author Topic: 12vAC to 120vAC  (Read 5798 times)

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Offline 555 timer chip guyTopic starter

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12vAC to 120vAC
« on: March 04, 2007, 08:07:14 PM »
I have been wondering how to steppe up 12 to 120vAC I have herd that you can use a transformer but need to know how to use one please help. :-[

Offline Admin

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Re: 12vAC to 120vAC
« Reply #1 on: March 04, 2007, 08:13:30 PM »
where are you getting 12VAC from?!?

120VAC sounds dangerous . . .

oh, and just know that if you step up voltage, you will also end up stepping down current . . .

Offline 555 timer chip guyTopic starter

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Re: 12vAC to 120vAC
« Reply #2 on: March 04, 2007, 08:31:48 PM »
where are you getting 12VAC from?!?

120VAC sounds dangerous . . .

oh, and just know that if you step up voltage, you will also end up stepping down current . . .
I am getting it from a 12v power inverter that I built that runs off of a 12 amp 12volt battery and current dose not matter for this application.

Offline gamefreak

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Re: 12vAC to 120vAC
« Reply #3 on: March 05, 2007, 06:26:06 AM »
lol, admin only current is dangerous, you can get millions of volts(i think) but if you get more then 50 milliamps you will die.
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Offline 555 timer chip guyTopic starter

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Re: 12vAC to 120vAC
« Reply #4 on: March 05, 2007, 09:10:15 AM »
lol, admin only current is dangerous, you can get millions of volts(i think) but if you get more then 50 milliamps you will die.
You are right about that

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Re: 12vAC to 120vAC
« Reply #5 on: March 05, 2007, 10:43:49 AM »
actually it is power that is dangerous . . . and power is a direct function of voltage times current . . .

only two ways electricity can kill:
-> burns caused by high power dissipation (voltage * current equals heat that burns cells)
-> high voltage interfering with your nervous system (stopping your heart from beating, etc.)

the other reason why i say high voltage is dangerous is because high voltage electricity tends to jump through the air without a wire connection. this cant happen no matter what the current . . .

Offline gamefreak

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Re: 12vAC to 120vAC
« Reply #6 on: March 05, 2007, 07:35:02 PM »
you said cant, you mean can, And yea Tesla coils are an example of that, they will shoot electric arcs through the aire which even though you cant feel are dangerous to your health, after a half hour to an hour your muscles might begin to hurt or you could lose control of them temporaily. Arent high powered devices fun? Van de Graff generator, tesla Coils, the weird thing made out of wires and aluminum foil that floats in the air by ionizing the air and forcing it to fly towards the aluminum, [Insert other High Powered Device Here], EMP.

And since we appear to be off track.... Yes i think you need a transformer, and a voltage multiplier which is some sort of set up of capacitors and diodes.

And remember Wikipedia is your friend: http://en.wikipedia.org/wiki/Voltage_multiplier , http://en.wikipedia.org/wiki/Transformer


Now what i figure is take your 12 volts and turn it into alternating, then use a voltage multiplier to raise it, and then change it back into alternating.

Also do transformers change alternating current into direct? i know they dont work with direct current.

Also wouldnt a transformer with a "Step up" set up raise the voltage?


Wait! dont normal house hold plugins give off 120 VAC?
« Last Edit: March 05, 2007, 08:29:32 PM by gamefreak »
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Offline Nyx

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Re: 12vAC to 120vAC
« Reply #7 on: March 06, 2007, 11:53:50 AM »
If you want to run any kind of 120VAC appliance, your best bet is to just buy a car inverter. Those are made to be plugged in lighter sockets. I got one that can provide 150W (350W peak) for only $18 at a local electronics shop... You can also get some less powerful ones for even less (50 to 75W), or some much more powerful ones (1000W).

As for the danger of 120VAC... I got shocked by household power lots of times as a kid, playing with electricity and electronics... Never got any kind of damage or adverse reaction. I would say 250VAC is alot more dangerous, and that well, the level of "danger" also depends on the circumstance. If you get shocked right on the chest, it may be alot worse than on the hands.

Offline 555 timer chip guyTopic starter

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Re: 12vAC to 120vAC
« Reply #8 on: March 08, 2007, 06:14:27 PM »
Thanks but I need an inverter that produces a square waveform non of the car inverters do that, thats why I am building one.

Offline sdk32285

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Re: 12vAC to 120vAC
« Reply #9 on: March 08, 2007, 09:34:49 PM »
Also do transformers change alternating current into direct? i know they dont work with direct current.

Also wouldnt a transformer with a "Step up" set up raise the voltage?

Xfmrs use AC for the input and also outputs AC.
Also you are correct that a transformer set up as a "step-up" would increase the voltage while lowering the current. the basic relashinship for a Xfmr is:
                                                                       (V1/V2)=(I2/I1)=a       
               where a= the turns ratio (ie. N1/N2 where N= coil turns), V=volts, I= current and  1 is the primary/input side, 2 is the secondary/output side.
« Last Edit: March 08, 2007, 09:38:09 PM by sdk32285 »
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Offline 555 timer chip guyTopic starter

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Re: 12vAC to 120vAC
« Reply #10 on: March 11, 2007, 09:36:21 AM »
Also do transformers change alternating current into direct? i know they dont work with direct current.

Also wouldnt a transformer with a "Step up" set up raise the voltage?

Xfmrs use AC for the input and also outputs AC.
Also you are correct that a transformer set up as a "step-up" would increase the voltage while lowering the current. the basic relashinship for a Xfmr is:
                                                                       (V1/V2)=(I2/I1)=a       
               where a= the turns ratio (ie. N1/N2 where N= coil turns), V=volts, I= current and  1 is the primary/input side, 2 is the secondary/output side.
Ok but the thing I need to know is what type of transformer and how to use it.

Offline sdk32285

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Re: 12vAC to 120vAC
« Reply #11 on: March 11, 2007, 06:28:30 PM »
I don't know if i completely understand what you want but here goes
You probably want a "standard single phase transformer" or "standard center tapped transformer" other types such as "isolation transformer","current transformer", "potential transformer", "3 phase", etc.. are probably not what you need.

For a Standard xfrmr:
A step up transformer and a step down transformer are the same thing, it just depends which side you connect as the input. usually there will be two wires (one on top on the transformer and one on the bottom) where you connect your PWR and GND (ie hot and neutral); and two wires on the other side which you treat as PWR and GND. if on the input side top wire =PWR than on the output side keep the top wire PWR.

Some Xfrms are center tapped (and have a third wire on one/both sides) which means that if the voltage ratio of the xfrmr is 1:10 than if you use the 3rd wire in the middle of the xfrmr you get a voltage ratio of 1:5. with this method you still only connect two wires, however you can design so that you have 2 systems each using half of the transformer.
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Offline sdk32285

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Re: 12vAC to 120vAC
« Reply #12 on: March 11, 2007, 06:43:29 PM »
Wait! dont normal house hold plugins give off 120 VAC?

If you use AC from the wall and are not using a transformer to drop down the voltage than its usually a good idea to put an isolation transformer between PWR and your device to prevent DC leakage, Noise, Ground loops,etc...

note:isolation transformer are just standard transformers with a turns ratio of 1:1.
« Last Edit: March 11, 2007, 06:44:18 PM by sdk32285 »
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Offline 555 timer chip guyTopic starter

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Re: 12vAC to 120vAC
« Reply #13 on: March 13, 2007, 11:33:19 AM »
ok but I need to know how to use one could you explain.

Offline sdk32285

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Re: 12vAC to 120vAC
« Reply #14 on: March 13, 2007, 01:16:27 PM »
http://upload.wikimedia.org/wikipedia/en/thumb/1/1d/Transformer.filament.agr.jpg/300px-Transformer.filament.agr.jpg

See the picture above.
Connect the black wires to your 12v source.
Connect the outer green wires to the device.

Is that what you need?
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Offline 555 timer chip guyTopic starter

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Re: 12vAC to 120vAC
« Reply #15 on: March 14, 2007, 08:11:41 PM »
thank you so much thats gust the striate answer I was looking for. :D

Offline ed1380

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Re: 12vAC to 120vAC
« Reply #16 on: March 14, 2007, 10:54:46 PM »
I have what I believe to be a small transformer from a digicam that was used to charge the capacitor for the flash. what's confusing me is that it has 3 contacts on one side and 3 on the other. what do they do?   -,grd,+
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Offline sdk32285

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Re: 12vAC to 120vAC
« Reply #17 on: March 15, 2007, 05:34:31 AM »
the middle one is usually a center tap. so for example if you use only the outer 2 wires on each side the voltage ratio is 1:10. if on the output side you connect to only one of the end wires and the middle wire the ratio is 1:5.
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Offline 555 timer chip guyTopic starter

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Re: 12vAC to 120vAC
« Reply #18 on: March 15, 2007, 04:48:46 PM »
can you use a transformer out of a plug in wall power supply because I Have one that has three weirs on one side (goes to device) and two on the other (goes to the wall).

Offline sdk32285

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Re: 12vAC to 120vAC
« Reply #19 on: March 15, 2007, 05:45:38 PM »
you should be able to. the xfrms rating should be on the transformer. input/ output voltages and current.
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