How many wires do i need to Power and control 6 servos

[speedlight1221]

Hello again.

I have a project that uses 6 servos that i need to control. The problem is that the arduino controlling them is located some distance away, so I need to extend the wires.
I plan to do this using a ribbon cable.

My question is how many wires are needed to do that. Obviuosly I need 7 for the signal connections, but do i also need a distinct power and ground wires for each, or can i somehow group them?

What is the smallest number of wires i would need for this.

They are MG995 servos.

Also what would the number be if I needed to connect 4 jx PDI-HV2060MG servos, since they are bigger.

Thanks.

[Paul_KD7HB]

Most all ribbon cable wires are for signals, not power. Limit each wire to 1 Ampere or less.

[jremington]

@speedlight1221

They are MG995 servos.

The power wiring will need to handle about 10 Amperes without much voltage drop. The longer the distance, the heavier the wire gauge required.

Keep in mind that servos draw the stall current every time they start moving (1.2 A for the MG995).

[camsysca]

6 ribbon, 2 heavier gauge power. Make sure you size those two for the maximum current that can be drawn by all 6 servos simultaneously.

[westfw]

@camsysca

6 ribbon, 2 heavier gauge power.

Or, you can "dedicate" multiple conductors in your ribbon cable to GND and PWR.
Most ribbon cable is 28g, which various sources say is good for 1A, and the MG995 data says:

No load operating current draw 170MA
Stall current draw 1200MA

[speedlight1221]

The project I am following does seem to do this. For both scenarios I mentioned they used 14 veins ribbon cables.

For the small servos they dedicated 4 wires for power and 3 probably for ground.

For the big servos, they have 5 power and probably 5 ground. However I would ideally need to reduce this count by one. Would it cause problems If I had one less ground connection?

If I was to do it this way, how would I wire it ? Would I need to connect all the powers together? And if wanted to power all servos together, would I need to increase the voltage?

Here's the link You'll need to scroll quite a bit down to find the part where they connect the cables.
The problem is that they're using their own boards, and I am not sure I will be able to get access to them.

[TomGeorge]

Hi, @speedlight1221
Is this associated with this?

Big servo slowing down

Hello. I am using a jx HV2060mg digital servo for a project. The project required me to remove the inner potentiometer and wire it outside the servo. However, now whenever the potentiometer is connected, the servo starts quite fast, but slows down quite a bit. I am powering it using a big battery and a step down module, which outputs 8v. Could it be just my bad soldering, or is there a deeper problem? Thanks for your help

Tom....

[Paul_KD7HB]

@speedlight1221

The project I am following does seem to do this. For both scenarios I mentioned they used 14 veins ribbon cables.

Please document how you are terminating the ribbon cable wires! Are you using the proper connectors for your ribbon cable? If so, the size of the strands has no bearing on the current capacity. The weak point is always the insulation displacing pins that are part of the connector. The surface of the pin touching the wire strands is very minimal, suitable for signaling, not powering.

[westfw]

@Paul_KD7HB

the size of the strands has no bearing on the current capacity. The weak point is always the insulation displacing pins that are part of the connector. The surface of the pin touching the wire strands is very minimal, suitable for signaling, not powering.

Are you sure about that? Running power through IDC connectors is a pretty time-honored practice. I checked a few IDC connector datasheets and they seem to mostly be rated for 1A - about the same as the 28g wire they connect to... (ie https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=6437006-5&DocType=Customer+Drawing&DocLang=English )

[Paul_KD7HB]

@westfw

I checked a few IDC connector datasheets and they seem to mostly be rated for 1A - about the same as the 28g wire they connect to..

All true, but NO measurement is made of the point of connection between the 1 amp steel connector pin and the 1 amp #28 stranded wire. That point of contact cannot carry 1 amp.

[anon2761406]

Shift register ICs allow you to multiply the GPIO of your board. For example, with five 8-bit shift register ICs, you can get 40 GPIO by using only 5 of your Arduino pins.