Electronics

PJ · Joined: 13 Sep 2006 Posts: 6

Wow... a whole forum to teach and help with electronics ! Man, I've been looking for this sort of message board.

Hi guys, my name is PJ... erm, I'm actually new (to this forum and electronics in general).

Well, I was wondering if someone could help me out with a project for my computer's sound card. Here's what I want to do...

I would like to take a headphone wire and put it into the mono of my sound card, cut the wire, and use the electricity to power a specialized electrical Tesla-like coil (which is called a "caduceus coil") that I have.

What I would like to do is use my sound edit program to generate frequencies with it - where the "sound" is actually not going to headphones or the computer speaker. The electrical signals would go into my coil where I can tune the electrical frequecies with my sound edit program.

Now obviously I need AC power for this and I need to amplify the electricity somehow. If I'm not mistaken, DC is what comes from a sound card's output. Does anyone have any recommendations for the best way to do this?

Thanks so much
PJ

stevew · Joined: 11 Sep 2006 Posts: 7

Hi PJ,

It's an AC wave form that's coming out of the output of your sound card. It does require a DC power source, which is what your computer power supply provides to the card.

The AC wave form coming from the sound card output is not a very strong signal, 'line level', just enough to power headphones at a low volume, or to feed the preamp of your computer speaker system.

If you want to strengthen the signal, you'll need to apply a pre-amp yourself to the card output, then pipe the output of that to your coil.

Hope this helps

SteveW

PJ · Joined: 13 Sep 2006 Posts: 6

Wow, sounds great ! Thanks stevew ! Very Happy

Just one last question... what would be a good pre amp to use for lots of electricity and where would it go concerning the wire and sound card for my caduceus coil?

Thanks again!
PJ

stevew · Joined: 11 Sep 2006 Posts: 7

PJ,

The wire coming out of your sound card should be a three-conductor wire, probably two wires, plus the shielding, which acts as the ground conductor. This allows for the two stereo channels and the return ground. Since you only need a mono signal, you can disregard one of the wires, and use just the other wire and the sheilding ground (assuming that the same mono signal is coming through both channels).

These two wires (wire and ground shielding) are what feed your mono preamp, which should take a two conductor input of some kind. The preamp will also have an amplified, two-conductor output, which is what you would run into your coil.

You can buy mono preamps for under $100, probably at Radio Shack, or over the internet.

A cheap alternative would be to use an old pair of cheap computer speakers ( many people have these laying around since they upgraded their computer speakers to something better than the cheesy ones that come with the system.). If you have some of these, you'll have to open one of them up and disconnect the wires that provide signal to the little speaker, and these would then be your pre-amplified output signal to feed the coil. If you go this route, just leave the wire that runs from the sound card to the speakers in tack, plugged into the sound card. Of course, you'd need to have the speakers powered by their associated wall-wart.

If this doesn't make sense, let me know where I'm loosing you, and I'll try to explain in more detail.

SteveW

PJ · Joined: 13 Sep 2006 Posts: 6

Excellent... it all sounds great.

I think I'll buy myself a mono pre-amp and that 3 conductor wire. Using both left and right outputs from the sound card seems realistic.

It make sense to me... thanks for all your help, stevew !

PJ

stevew · Joined: 11 Sep 2006 Posts: 7

PJ,

A note of clairification here.

I may have been misleading in calling the unit that you would amplify the output of your sound card as a 'preamp'.

Technically speaking, the line level signal coming out of your sound card is already at 'pre-amplified' level. So in fact, if this signal needs to be of a higher level than the already 'preamplified' leve, you actually need an 'amplifier'.

So you'd be better off not shopping for a mono 'preamp', but a mono 'amplifier'. This could be correctly identified by the characteristic of amplifying a line level signal to the level where it could be projected through speakers.

Sorry for any confusion this may have caused.

SteveW

PJ · Joined: 13 Sep 2006 Posts: 6

That's Ok, stevew. I understood what you've been getting at.

Do you have any name-brand recommendations for the amplifier and wiring?

Thanks again!
PJ

stevew · Joined: 11 Sep 2006 Posts: 7

Looks like something like this might do the job for you:

http://www.radioshack.com/product/index.jsp?productId=2062620

caveat: This takes a microphone input, not a line input like your sound card, so you will get a strong, but perhaps somewhat distorted output since it's intended for a lower voltage input. If you turn your sound card output all the way down on your computer, this may be ok.

Another option would be this:

http://www.amazon.com/Sonic-Impact-15-Watt-Portable-Amplifier/dp/B00009W44B/sr=8-3/qid=1158356388/ref=sr_1_3/103-6395622-6405469?ie=UTF8&s=electronics

This has two channels (stereo) of which you would only use one, so it's more than you need, but it does take a line level input such as your sound card, so the impedance is matched, minimizing distortion.

As for a cable, you'll need a stereo or mono 1/8" male/male cable such as:

http://www.radioshack.com/product/index.jsp?productId=2102950&cp=&origkw=cable+1%2F8%22&kw=cable+1%2F8&parentPage=search

One other option you might consider - If you have any old stereo amplifier lying around, such as for a home stereo system, this would work.

Disclaimer: With all such projects, there is tweeking and troubleshooting required in order to get your desired end result. I can't guarantee that these things will give you the results you are looking for. If it were my project, it's where I would start.

Good luck!

neon · Joined: 25 Feb 2006 Posts: 590

stevew · Joined: 11 Sep 2006 Posts: 7

That's a good pun, 'miss leading' the guy. I would deffinitely want his leads to be correct!

But seriously, I'm open to the possibility that I'm wrong here. How would you carry two (stereo) channels and return ground with only two wires?

neon · Joined: 25 Feb 2006 Posts: 590

Seriously you may multiplex many chanels on two wires. A shield is there for one purpose only is to shield RF and others sources. Besides a shield is a very noisy as a conductor because it generates noise. connecting disconnecting wires continiously as it flexes.

PJ · Joined: 13 Sep 2006 Posts: 6

Well I tell you what, guys... is there any such thing as an amplifier where you can adjust how much power can amplify electrical frequencies (sine, saw, square, 16hz, 160000hz, etc.) where I can go to maybe 100 watts? I'm sure if I put the left and right wires from the sound card's output into the amps input that should do something. Or no?

PJ · Joined: 13 Sep 2006 Posts: 6

Take a look at this:

http://www.brinkmann-usa.com/calvinpreamplifier.php

Would this give me what I want for the caduceus to work? Or would I need a much better amplifier so I can adjust much more power going into the caduceus?

stevew · Joined: 11 Sep 2006 Posts: 7

PJ,

Not sure what a caduceus is. The amp you have the link for looks to me to be a preamp, and I'm thinking you need an amp, not a preamp. Certainly if you're looking for 100W output.

neon · Joined: 25 Feb 2006 Posts: 590

Look up national LM4651,52 OVERTURE OUTPUT POWER INTO A 4 OHM SPEAKER IS 170W TYPICAL 20 to 200kz it is a class D amp. Needless to say you will need a new power supply to supply this monster. Cost of the amp is $12.00 but you must make it yourself. Buy it all made up if you can afford it. Cheaper to buy it as an audio amp.

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