PC-DC server Help

[konio38]

First of all i would like to thank you for acepting me in the forums, its great that the DC comunity is so strong.

I have been trying lately to set up a pc-dc server, now long story short i have a PAL modem, and of course i need that line voltage inducer, my question is simple is there anyway i can pass on the LVI? in my country its hard to find electronic components what so ever, i tried to find a resistor arround my broken electronics with no luck and i cant aford a NTSC model A modem, so has i said is there any workaround to my requirment of a LVI?

Thank you for your time and i hope you guys can help me.

EDIT: Also how do i know if my modem if voice capable? i have here 3 modems two of then have 2 jacks one for internet and one for phone, are those voice capable? The other one only has one jack.

[brourke228]

Do this: http://www.ehow.com/how_4877564_own-res ... iment.html

I was able to get a resistance of 298ohm at about 1/8th mm between the multimeter probes. Use a normal pencil and push down really hard on the paper.

And you can do this to make a capacitor: http://www.ehow.com/how-does_4852927_bu ... citor.html

Measuring the capacitance is more difficult, but for a line voltage inducer the value of the capacitor shouldn't be too important, as long as it stores some charge. However if you need to increase the value just make a few of them and place them in parallel. To decrease capacitance you put them in series like this ----||--||---||--

[konio38]

actualy for the capacitor im fine has i have found one that had 1 uF so now i only need the resistence and for the socket im going to use an old modem power socket.

EDIT: what is the best way to connect the wires to the paper? duck tape? glue?

Also wont the paper burn when theres current passing by it?

[brourke228]

No, the paper won't burn. I would just poke the wires through the paper where you've determined is the correct resistance. Then tape it to the paper with some scotch tape or masking tape. Make sure the copper is making contact with the lead on the paper. You can test the circuit afterwards by measuring the voltage difference with respect to ground.

[konio38]

im having troble making the resistor with such low values, i the lower i could get was 104 kohm

[brourke228]

Push down really hard on the paper. And remember, the closer you place the probes together, the lower the resistance value will be. You will need to connect the wires to the paper very close together. Like i said before, i had the probes only about 1/8th mm apart which is verrrry close.

Here you can see I got 713ohm. Obviously I wasnt being very precise because i was trying to hold camera with my other hand You will probably need some real thin wire for this.

[konio38]

yeah i know, im trying its like microscopic stuff XD

[konio38]

i cant do it its too damm small, i got it to 0,7 kohm but even if i get it i wont be have to join it with the wire.

BTW about the modem i was correct to assume what are the ones that are voice capable?

[brourke228]

You could make multiple resistors and do a parallel combination of them. Combining resistors in parallel will decrease the overall resistance. The formula for parallel combination of resistors is

Code: Select all

Rtotal = (1/R1 + 1/R2 + 1/R3....+1/Rn)^-1

For example if you used three 1kohm resistors in parallel the combined resistance would be

Code: Select all

Rtotal = (1/1000 + 1/1000 + 1/1000)^-1 = 333.33ohm

So just pick a reasonable distance, make a few identical paper resistors and connect them in parallel. Use that formula to calculate out the resistance you're looking for.

Don't worry about your modem being voice capable, I don't think that is a necessary requirement. I have used a data/fax modem and it worked just fine.


I would just use six 2kohm resistors. That would still give you an Rtotal of 333.33ohm. 2kohm is about 2mm apart so it should be easy enough to work with. In that case your line voltage inducer circuit would look like this:



When you're done making the circuit you should probably set it up somewhere where it isn't going to move because obviously with paper resistors it will be quite fragile.

[konio38]

ok so after making about 10 2kohm (made a few more just in case) resistors it still proved to be very dificult to actualy make everything hold i managed to get the circuit made, but as soon as i moved the cable, everything broke free. give it 2 more tries with no sucess so im just gonna give up on the paper resistors i reallu have to get a normal one, even if i have to order 100 of then from china. Thx brourke for everything i only saw the circuit you made now, its very nice of you to actualy make a drawing thank you again.

I will hopefully get a resistor, and make this.