2 Wire Tether? Plus camera lines...

[mrtristanplaysguitar]

Hi.

For my next ROV I am trying to wire 3 motors and light(s) on the same relay circuit so that I can control it with a joystick and some switches. And I'm hoping for a tether that's not gigantic.

While researching, I found this:

http://www.apogeekits.com/remote_control_2_wire.htm

It looks like its perfect if I can extend the 2 wires to my tether length. That kit would make my tether 2 wires plus whatever camera lines I have.

Does this look like it would work for my purposes? The remote control says outputs can be buttons (ie, joystick).
Would it be hard to set up the system? I don't really know anything about microcontrollers...

Thanks for any feedback

Btw, all power will be from a 12V DC power source on the surface except power for monitors (on surface) and lights (onboard). The lights will get a relay so I can control them with a button on the surface.

[sthone]

The K8023 is good way to keep the tether thin but it can only be used for control. The outputs can only handle 100mA so you would need to use a relay setup to handle the higher amp draw of the thrusters and then that kit could be used to control the relays coils. So you would still need to have a main power feed in the tether or use on board batteries. In other words you can not just plug your thrusters directly into that kit and control them that way (I know because I tried that about 10 years ago when I didn't know any better ) I have tested these kits out and they do work out to at least 300' (some one told me he tried them through a 1000' roll of cat5 and it still worked)

-Steve

[mrtristanplaysguitar]

So if I had 2 power lines going down to my relay setup plus the 2 control lines that would work?

Also, what kind of relays would I need to use? Could I still power the relays through that 12V DC (car battery basically) thats on the surface?
Basically I'm wondering how to power/control the relays through that kit...
To control them is it just matching up pairs on the input and output of the kit and then putting switches/buttons?
To power them can I run it off of the same power source as the thrusters, right?
And what about powering the microprocessors (control and recieving PCBs) ... thats what theyre called right?

- Tristan

[thegadgetguy]

Yes, you could have two power lines plus two control lines and that would work, assuming that you wire everything correctly.
For relays, you would either need two DPDT (Dual Post, Dual Throw) relays per thruster, or one H-Bridge relay per thruster. (H-Bridge relays are basically two DPDT relays inside the same housing)Here's a link to Steve's webpage about this: http://www.homebuiltrovs.com/howtorelay ... ridge.html Assuming that you get a 12 volt relay (although others have used relays that aren't 12 volts) you will just wire up the 12 volt power from the surface to the power input posts on the relays.

I am assuming that you want forward/reverse control of each thruster, so how to wire up the everything is best explained by a diagram. (Steve has made some good ones in the link)

Essentially a relay is an electronic switch, that is moved by an electromagnetic coil. When your low voltage signal from the K8023 unit passes through the relay, it moves the electromagnetic coil, which switches on the higher voltage 12 volt power to the thruster. The low voltage signal, from your onboard electronics, is powered by whatever's powering your circuit board. The relays have 12 volt input posts on them, which is the power actually going to the thrusters.

The K8023 unit requires 12 - 15 volts, so the voltage is correct, but you may want to do something to limit the amperage, as the unit only requires 300 miliamps and a 12 volt battery has many more than that.

Hope this helps a little, Steve will probably chime in with a better explanation when he can.

[mrtristanplaysguitar]

Sorry to seem so clueless, but how would you go about limiting the amperage to the board?

I understand how relays work, i was wondering if it would work to power everything (thrusters, control boards, relays, camera) off the same 12 volt dc battery. Lights would be powered by onboard battery with a spst relay going to a push button (not momentary, the other kind). Does this sound do-able, or should i scratch this idea.

I sort of am looking for confirmation that my circuit (providing i wire it correctly) will, well, work.

Also, i think the camera will have its own power lines, ie i don't want my thrusters messing with my camera.

[Tsilatipac]

I know that this is a fairly old thread but I thought I'd speak to limiting amperage. You do not need to limit amperage for the control circuit, the system will only draw what is required. The key is to make sure that your voltage source meets or exceeds the needed current (amperage). To protect your electronics from damage, due to an accidental short, it is advisable to put a fuse on the positive power feed line close to the voltage source. Size the rating of your fuse based upon your system needs and limitations. The fuse is limiting the amperage, but only to protect if a short occurs.

Hope that helps a little.

[thegadgetguy]

Yes, sorry, that is what I meant, although I don't think I got the point across very clearly.