HoloTheWolf

Just received the TK22 board for my Leo2A6. I am thinking about putting the board inside the turret which is quite roomy.
To work with my slip-ring version turret 360 degree rotation mod, wires from the lower hull (7.2v battery, motors, speaker)
have to go through the slip ring.

Now the ring I used can take 220V and 2 Amp (per circuit), but those wires look very thin. I am wondering can the ring
work with those battery and motor wires from the lower hull? Will the current from the battery burn the ring?
Anyone have comments? Thanks!

HoloTheWolf

Check the spec of my NiMH battery: 7.2V, 3A. So I guess the ring is not gonna work.

danlrc

The battery is 3 amp-hour, not "3Amp". Amp-hours is a capacity rating meaning the battery can deliver approximately 3A for 1hr, or 1A for 3hrs, etc. The device drawing current from the battery is what determines the amps in the circuit.

The slip ring may not take the motor load, but should easily handle all the other functions like lights, recoil, elevation, turret rotation, etc.

I have a 12 wire slip ring that works fine (220V, 2A), but I don't have the motor wires going through it. If you have enough wires in the slip ring (some have up to 24 wires I think), you can use two or three of the slip-ring wires grouped together for each motor lead. They will "share" the current load and I'm guessing that would be enough to handle the motor current draw.

HoloTheWolf

Great! Thanks for your explanation danlrc. I don't know too much about electronics, so that is extremely helpful to me.
And the idea of grouping wires and sharing the current load is excellent. I may give it a try.
Thanks again!

heavyaslead

I had the same design question when I did my Leo and Black Eagle conversions.

The contacts can experience high current especially when motor stalls, like tracks bind up in grass or other sticks or rocks.

So I used an 18 circuit version and tied 4 circuits together just for the motors, I figured that would cover about 8 amps stall or if one of the contactors goes bad.

HoloTheWolf

Thanks Eric. PM'd.

danlrc

Holo, Eric,
On my big RC sailing ship models, I learned a long time ago to fuse all the circuits because of rigging snags, etc. I fused my KT and Tiger1 at 5A and have not had a blow. Easy and cheap to install and you can start with a low amp fuse and go higher if necessary til you find a stable fuse value. Keep fuse value below slip ring rating and all should be OK I think.
Here's a pic of a simple, small fuse setup. ATM fuse, female blade terminals on wire ends, heat shrink terminals. Almost any value fuse is available.

danlrc

duplicate sorry

heavyaslead

Good advice, but the Leo DMD will protect with its own current limiting output protection on the FET's. The max momentary surge on the FET's is about 20A, so continuous would be about 10A max, but RMS continuous would be more like 7A under stall.

gottaname

Hi Holo,

From rc tank divsion in singapore, lurking here most of the time. Decided to post because of the questions on slip rings keep coming up.

I've fitted a 24 wire slip ring off ebay on my HL leopard 2A6. However the configuration is such that the TK22 board remains in the lower hull with the battery. There is no high tension flash and the flash is replaced with an white LED.

The reasoning is the same problem as you have. The slip ring is designed for sensitive signals to be transmitted through it (CCTV video for instance). It is still safer to use the slip ring to carry over servos, MG light, barrel flash, TBU instead of the method you worked.

So far there hasn't been any major electrical/electronic issues concerning the slip ring, although initially issues such as TBU sensitivity, IR range and such was presumed affected, however the tank has been dry tested and has been in quite a few matches so the concerns are debunked.

There has, however been issues concerning turrent rotation.

1. The slip ring wiring must be done correctly and anchored to the turret ring (as you can see in the picture), or else the slip ring won't be allowed to rotate properly and tangled causing the turrent rotation unit and motor to blow (cost me a tk22 board). I've countered this problem by getting the generic tamiya 4WD motor, dismantling it and greasing it up and gluing the clutch in the HL turret rotation unit.

2. Due to the slip ring being placed in the central axis of the turret, The barrel assembly may not have enough room to elevate or depress, and causing problems like in point 1.

Other than that, the slip ring has proven very useful and I don't have to worry about making too many turret rotations, however caution has to be placed on making sure the turret doesn't jam.

heavyaslead

It is important to get the high quality slip ring (the KEYO uses gold contacts and silver tined wires) (They also make a 4A version though more expensive)

In a Tamiya tank with the Tam Leo electronics, never had an issue using the slip ring, the slip ring set in the speaker box hole has plenty clearance for gun elevation.

I actually have installed the slip ring in all my tanks, Pz4, Tiger, KT, Pershing and T55 all with no issues

gottaname

Heng Long leopards don't come with recoil and extensive modifications must be done to the elevation unit, this problem won't be apperently in a tamiya leopard. Was posting to to holo because he's using a Heng Long leopard from the looks of it.

When I do get my tamiya leopard or JS-2 in the future, I'll probably mod a slip ring. The Heng Long is warm up because modifications may damage expensive tamiyas.

The unit I'm using is MOFLON one, but all the slip rings are made in china still and all gold plated/contacts apperently, I don't think slip rings from different manufacturers make any difference since you'll never hit the max rpm count on the unit or actually wear the thing extensively enough.

heavyaslead

Oh sorry, did not understand the model Leo he was using.

And you're right, the RPM is negligible for considering wear and contactor rating, should last a lifetime!

danlrc

Hey Eric,
Right. But if you want to try a slip ring to carry a high load, and say you want to use three 2A rated contacts to get 6A current capacity, add a fuse of about 5A (closest ATM fuses I've seen would be 5 or 7.5A) to protect the slip ring. If the fuse blows under normal operation, you can rewire around the slipring without having wasted it. If the lower amp fuse doesn't blow, you can keep the slipring and protect it with the fuse.

On my Tam KT, I have a 5A fuse and have never blown it (light use, but I did battle one time at Danville). Cheap, easy to see and easy to replace. The tank has a separate black powder gun-igniter circuit that pops 5A ATM fuses, but is OK fused at 7.5A. I run that circuit thru a single wire pair thru a 12 wire, 2A slipring and haven't had an issue yet. But that is a quick surge current - it melts a thin nichrome wire and the current stops. Will be interested to see how long the slipring lasts. Bought 5 for $15each from China. Seem to be great quality.

HoloTheWolf

Guys, thanks a lot for numerous tips on using the slip ring. I may give the "fuse" approach a try because putting the
TK22 board in the turret saves a lot of space.

Dan, about the fuse, I see from your photo that those are ATM fuse correct? I found an in-line fuse holder on Amazon:

http://www.amazon.com/In-line-ACT-Wa...ickstream_2_dp

My idea is to group 3 2-amp slip ring wires together and solder them to the holder. Is this gonna work (and safe) ?

danlrc

The holder will work fine. Start with a low amp fuse and if it blows, go the next higher value. If you get to 7.5A fuses and they are blowing, you might start thinking about whether you keep using the slip ring (which should easily handle 6A over three wires).
I make fuse holders with "flag" terminals. Cheap, easy, small finished holder. Just put some shrink tube or insulation on the bare terminals.

Max-U52

Any chance we could see some pix of the interior of the Tiger or the Pershing with the slip ring installed? Please?