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Discussion Starter #1
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
 

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Macho Nacho
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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.
 

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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 . :)
 

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Macho Nacho
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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.
 

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Discussion Starter #6
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
 

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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 .
 

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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.
 

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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.
 

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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.
 

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Good point. Speaker wire's cheaper anyway. I always did have a bad habit of over thinking things...
No worries, if he were not to use single CAT5 wires for power, then your idea would work fine. Some people have more current requirements that I may not be aware of.
 

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Discussion Starter #13
So am I hearing that it would be ok to send power via a single cat5 cable to a six-axis skull? That would mean six control wires and only two for power.

Dr. M, you've run DC power through a single twisted pair to a six-axis skull with no problems? How long was your run?

Ideally I'd want to do it that way, and run a separate speaker wire for the audio, but I've been worried about the current draw on such thin wires. I'm interested in hearing from folks that have done this successfully.

My setup is a SSC-32 control board next to the host PC indoors, with a 9V 17A power supply. My audio is a 5-channel surround receiver sending amplified audio to individual speakers. I run all the wires from here to the display outside.

Thanks,
dgm
 

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So am I hearing that it would be ok to send power via a single cat5 cable to a six-axis skull? That would mean six control wires and only two for power.

Dr. M, you've run DC power through a single twisted pair to a six-axis skull with no problems? How long was your run?

Ideally I'd want to do it that way, and run a separate speaker wire for the audio, but I've been worried about the current draw on such thin wires. I'm interested in hearing from folks that have done this successfully.

My setup is a SSC-32 control board next to the host PC indoors, with a 9V 17A power supply. My audio is a 5-channel surround receiver sending amplified audio to individual speakers. I run all the wires from here to the display outside.

Thanks,
dgm
Well, I'm not recommending it, I'm just saying that I'VE done it without any problems. I've run 3 regular servos PLUS my wiper motor servo using singles wires, (not twisted) for power. Now, realize that not ALL the servos are moving at the same time all the time, if they were I'd consider using a twisted pair for each POS and NEG power. I've run 75' this way.
 

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Discussion Starter #15
Seems to me that the jaw servo and 2-axis eye servos wouldn't be drawing much current. But the nod, rotate, and tilt servos can easily pull a few amps, especially with the bucky skull's weight.

Perhaps a Lindberg skull is the way to go for this project. I think I'm going to give it a shot.

I release you from any liability :)

-dgm
 
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