Thread: Wiring for 3-axis skull - power and audio in CAT5?

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I built a 3-axis skull last year, and used cat5 cabling to carry the 4 servos' control signals, and the DC power straight from the SSC-32 board. This worked great. I ran another cable to carry the amplified audio to the nearby speaker.

This year, I want to add 2-axis eyes to another 3-axis skull. This means six signal wires will be needed, and the necessary power, plus the audio. Clearly the two remaining conductors in the cat5 won't be able to handle the current demands of six servos.

So I'm wondering if I can use a second cat5 cable to carry both the servo power and the amplified audio. (I'd love to use a single cable to carry the control signals, servo power, and audio signals, but a cable with that many conductors is totally cost-prohibitive for me. Although Grainger seems to have some interesting options...)

Question for you electrical experts:

• Do I need to worry about any interference by running a DC power load alongside an amplified audio signal in the same cable?
• I plan on doubling up the conductors for + and - on both, will that be sufficient for a 30' run?
• Can I take advantage of the twisted pairs to eliminate interference? If so, what twisted with what?

Thanks,
dgm

I run the sound system in a theater, and I would have to advise against running your audio cables next to power cables. Heck, we even have the power to our speakers on a separate circuit from power for lights, etc.

I can't be certain if it would make a significant difference in your situation, though.

Originally Posted by Mr_Chicken

I run the sound system in a theater, and I would have to advise against running your audio cables next to power cables. Heck, we even have the power to our speakers on a separate circuit from power for lights, etc.

I can't be certain if it would make a significant difference in your situation, though.

Yes I have had problems with running power and audio right next to
each other. It makes the sound fussy. It also happens with radios and
the lines to the speakers and power.

Would adding a ULN2803 at the end , nearest the servos be out of the question ? If not , this would probably be the best idea if your not wanting to change your cable setup . That way , all you need to do is add a small 6 volt , say , 1 amp , wall wart near the ULN and servos .

Originally Posted by milemarker

Would adding a ULN2803 at the end , nearest the servos be out of the question ? If not , this would probably be the best idea if your not wanting to change your cable setup . That way , all you need to do is add a small 6 volt , say , 1 amp , wall wart near the ULN and servos .

If you would do that why wouldn't you just put the whole
card at the end.

I have the card indoors next to my computer, and plan on adding talking skulls in different locations in the haunt, but I need central control. I could use a separate wall wart for each skull, but I have a 17amp power supply that's ample enough to provide current for many skulls at once.

I guess I'll just run three separate wires: 1 for control signals, 1 for power, and one for audio.

-dgm

If you would do that why wouldn't you just put the whole
card at the end.

Well , for a few reasons .
1) pends on what card your referring to exactly . For example - IF you were using a setup with a KIT 74 , ( or any other setup using parallel port ) your distance is VERY limiited from the PC to the board , but NOT from the board , out .
2) less risk of theft of the control board(s)
3) not subject to inclimate weather .

running a CAT5 for 6 servos with power is fine. I even used it to power my wiper servo with 3 other servos and no heat.

If I'm reading this correctly, you want to send amplified audio (not line level) to raw speakers at the prop locations, along with DC voltage in the same Cat5 wire? If that's the case, I say go for it. There's no amplifier at the receiving end of the run to amplify the noise, and assuming you have a decent power supply there won't be that much noise in the DC. There might be a little bleed through at the speaker, but I doubt you'd hear it at the props viewing distance. If you double up on your conductors, use one conductor from each twisted pair for positive and the other for negative. Use (for example) the orange and brown for positive, and orange/white and brown/white for negative. You should be fine.

Well, If I'm reading this correctly, He would need seperate audio wires anyway seeing as how all 8 wires from the CAT5 will be used for the 6 servo skull. Save your money on CAT5. Run plain speaker wires to your skull.