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Paul Schoen

Wiring from scratch (china model)

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Hey folks,

I'm new to the forum and new to Steadicam operating. Currently, I'm practicing with a cheap chinese steadicam knock-off. It's fine for what it is and I'm just getting started so it wouldn't have made sense to invest in an expensive rig from the beginning (financial situation aside). So I've been practicing and the rig is really ok and I'll be able to use it for some more time until I can afford a professional rig. 

Besides the ok working mechanics, the electronics are not existing or just not really useful. So I planned some diy battery and wiring upgrade.

Things I want to do:

- Coiled center post cable

- bottom j-box

- top j-box

 

So far I think I got all the wiring plans right, but there are still a few questions I couldn't really find an answer to.

Because I wan't to run an HD-SDI wire through the center post too, I've been searching for ages to find some coiled hybrid cable that's not too thick. I already wrote "Sommer cables" and asked them and they wrote back and said that it's mechanically impossible to have 1 75Ω coax and 3 conductor wires in one cable and coil them. I'm pretty sure that it's just wrong because in all the pro gear it's done like that.

I thought further and I came to the idea that maybe I could run a coiled 3-pin condunctor cable down the post and tape (or whatever) a RG179 HD-SDI wire through the middle so that it's kind of coiled too. Not the best option, but if I won't get a hybrid cable (for not too much money) than maybe that's the way to go?

 

Second, because I want to be able to distribute 12V or/and 24V I'm still not sure of the AWG. Thought about wiring something like 0,75mm² (18,5 AWG) or 1mm² (17) through the post. The centre post is not as wide as the professional ones so it won't be possible to use 14AWG. I found some topics about this here in the forum but they all compared 22/20 AWG to 14AWG. Of course 22 is not enough (if you want to be prepared), but let's say the biggest camera I'll be flying is something around an Alexa Mini. With a max 90Wh power draw I should be fine with even 0,75mm². I'll still be able to power a few accessories of the top j-box. I plan to wire everything in the lower j-box with 1,5mm² (15,5 AWG) so there won't be a problem there with additional accessories.

Next question is about the connectors. In the first place I thought about going with the LEMOs and I will do for some 12/24V outputs (FGG.0B.303), but they are way too expensive for the whole upgrade (we're still not talking about a pro steadicam here). Then I asked myself: Why not use standard 3-pin XLRs? They are cheap, have a sturdy and safe connection and are able to stand up to 15Amps. I'll be using them for the centre post connectors and the main cable from the batteryplate to the bottom j-box.

Last one (I think): I'll be wiring some fuses into the bottom j-box too. Thought about 5A for two 12V D-Tap connectors and maybe soemthing around 7A for the 12/24V Lemos (AUX) and the centre post connection.

I attached a wire diragram (sorry for the test license). Upper left is the batteryplate, upper right is the bottom j-box. (Underneath is a quick diagram for an additional 3rd plate, not sure if I'll build this or not)

 

So, a lot of questions and I hope that some of you guys that are more experienced can comment on anything.

Thanks and cheers,

Paul

 

 

 

 

 

 

Wire_Diagram_PowerSupply_Video.jpg

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Paul;

I made it through part of your post.

Here is are several takes you may not have considered.

1) You seem to be trying to do everything and every contingency with a "lesser" rig.

2) It is, even by your own admission, not the perfect rig.

3) You're going to spend a tremendous amount of time and money on this thing.

4) If you do manage to get all of this done you'll almost certainly overload some of the components of gimbal and top stage and post and arm and vest and something bad will happen!

5) So, my take, why not do half of what you are planning, spend half as much time and money and then use the rig within its weight and purpose built range then move up to a more "purpose built" rig?

6) You're trying to do what we all want to do, make a cheaper rig do more than it should and be able to charge more for your services without investing in the gear.  No fault of yours we all want to doo that.  Investing is good; you get tax breaks and you end up with good/perfect gear for the job (not homemade stuff) and you get to charge a lot more with much better paydays!

I wish you good luck and maybe someone can help you with the wiring.

Janice

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Thanks for your advice Janice, I appreciate it.

I'm not planning to use this rig in a commercial way (Unless I'm pretty sure that it's going to work). It is more for practice and tests and unpaid shoots with friends. The time is not an issue for me (as it's more of a passion project) and the costs will be rather low. If it's finished I'll figure out what will be possible with this rig and what will be the max. load.

 

Regarding the wiring:

I figured a crucial mistake! I'll definitely need to install Diodes to prevent the current from firing back into the battery, causing shorts and accidents.

I would be really grateful for tips and feedback. =)

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