darkith

Here are the notes I've made on the TK-RX18 in the StugIII. Thanks to TXTanker for supplying a second RX18 for testing on.

David


Power system

Uses FETs instead of darlington pairs (like the TK-RX13). The tank is faster and quicker to super-spin than the TK-RX13 tanks, due to the FETs passing higher volts to the motors. Half the FETs are different than the TK-RX14 boards.
The high pitch PWM noise from the ESC seems more noticable to me, possibly due to the FETs, or a high frequency PWM drive (more efficient)


FETs are:
International Rectifier IRF7328 P-channel (8 pin SOIC)
Dual channel P-FET (2 x 7 amp FETs, used in parallel by HL), 14 amps max combined under optimal cond.
Safe region is 4A/FET, for 8A total sustained
But due to heat dissipation, probably limited to 6 amps max without additional cooling

Fairchild ISL9N310AD3 N-channel (3 pin TO252)
Very hefty FET (35A/70W sustained under optimal conditions!)
Even derated, should be good for between 10-15 amps

This board is a definite improvement over the TK-RX13 boards (which have about a 3amp sustained) and a very marginal improvement over the TK-RX14 boards (which were theoretically good for 8 amps, but probably only more like 4-5 amps without more cooling).
The TK-RX18 board had quite a bit of peak current handling, but has limited thermal cooling capability due to the small PCB size. A stock board without additional cooling is probably going to be limited in the ballpark of 6 amps or less (depends highly on ambient temperature and airflow inside the tank).
Heatsinks may help, but have to be placed cautiously to avoid impeding airflow to the board (which is the designed heatsink) and having a negative impact. Effective heatsinks could be soldered to the Flange of the N310AD and the common drain pins (5-8) of the IRF7328, but would need to be electrically isolated from each other and therefore tricky to implement.
What this board really needs is airflow. Vent holes in the case around the FETs, and a fan blowing over them (especially the IRF7328s which will likely fail first) will permit a fairly high sustained power level.

So, overall, a good improvement over the RX13s. The board can probably handle short periods of stall current or track snags. Stock tanks should be very reliable in comparison to TK-RX13 based tanks, so fewer tankers will be turned off by blowing the board as soon as the fire up the tank for the first time.
Metal tracks alone will probably be okay, though venting the RX18 might be a good idea for long runs in hot sun.
For more reliability (especially after adding weight), vent the RX18 and add a fan.
And yes, these may be conservative ratings, but I want to err on the side of caution.


Battle System

Not Tamiya/DBC compatible. It is using 38khz IR, but the signaling bitrate and bit pattern are totally different. Should be possible to use the HBU as a DBC sensor though, and likely the IR LED (though the range needs testing). No weight classes or speed change with damage.

The tank fires the IR signal even without the HBU plugged in.

IR LED uses a 22 ohm resistor on RX18 board. Can probably be used with DBC with 10-22 ohm resistor, pending range tests.

The hit and death motions are really cheesy.



Recoil System

Recoil motor is initially driven by the same circuit that drives the Airsoft gun on Airsoft tanks. You can blip the motor a few times (partially retracting the barrel) before the microswitch kicks in.

Microswitch on side of Main Gun
-Front Pin is to motor (negative side, normally open, completes circuit until recoil finishes)
-Middle pin is B- supply from RX18
-Rear pin is to RX18 (triggers track recoil and IR blast), also feeds power to Main Gun flash LED
You can pull the (white?) trigger wire wire from the "M.G. Fire" connector to stop the track recoil. Don't pull the whole connector or you'll dim the Main Gun flash LED a lot or entirely. You will lose the IR flash and sound effect when using the stick though (they'll stick work on the K button).


M.G. Fire socket has pins for both the stock Main Gun flash LED and the hop-up optional part #3868-006 "High-tension Flasher" , which I assume is a strobe flash for a greater flash effect. There are three pins, power, ground, and a 5v trigger signal output which gets a short pulse as long as the recoil wire from the main cannon is left plugged in.


Barrel recoil is bass-ack-wards. The motor starts driving it back until the microswitch (which doesn't get triggered until awfully far back) latches and provides power to the motor, which then drives it back all the way (triggering the flash and track recoil at the *end* of the barrel recoil). The barrel then snaps forward by spring power.
I think the barrel should snap back under spring power, and at the same time the LED should flash and the tracks recoil (if you like the track recoil), then the barrel should move forward more slowly under motor power. Hopefully this can be modded.

borealis

Great report, Darkith, and I fully agre with your considerations about the barrel recoil and flash.

The 'hop up' flasher should be this one, found on asiatam site ("Blitzheineit fur Stug III"): it has no description though.

darkith

Yeah, the flasher is in the Stug III manual as well. Looks like a strobe flash like the Tamiya one.

D.

971wright

Hi Dave from what you have writen are you going to do a battle circuit for the stug and panzer4 when it arrives or will it mean reverting to the rx14 board will it be posible to use the new dbc so we can get away from the 4 channel setup, as for recoil would it be posible to use the new recoil units which are out now would love to have a stug but only seen one for sale so far and that went for silly money over $200 .will have to wait here in the U.K. till someone gets hold of them and puts them on the bay still cant get hold of King Tiger here.


regards pete

darkith

Hey Pete,

Blitz has already confirmed that the DBC works with the new TK-RX18 board. I've got one almost hooked up, but have a cold and have been working slowly.
It should be possible to hookup the Heng Long Infrared sensor (HBU), flash LED, and probably the infrared LED to the DBC. Don't know if their infrared LED will have enough range though.

So, you should be able to use either the DBC-HL or DBC-RC2HL. The recoil unit is triggered by the old airsoft stick, so it's not synced with the cannon. I did see on RCU where somebody had rigged a micro switch on the airsoft stick to trigger the "K" button, so you could sync the two functions together. There's no direct way of hooking up the recoil units to the DBC. It might be possible by tapping off the infrared signal to drive a FET and power the motor until the microswitch latches, but the 1 second IR burst may be too long and cause multiple recoils. Maybe a future DBC might be tweaked to use the recoil unit (instead of the current servo based recoil option).

David

Planedev

Hey David, does that strobe come with all stugs or is that an upgrade that asiatam made?

If its stock Hl, then is it possible to connect it to the DBC-RC2HL in anyway, I am not too happy with teh led flash as its a bit slow and unrealistic as it is now.

darkith

Planedev,

I just noticed it in the manual...haven't actually seen one or heard of any tanks coming with one. Bill might know more, perhaps it's a factory orderable option (the manual also shows the metal gearboxes, tracks, and sprockets as options) or an aftermarket option.

It should be possible to hook it up to the DBC-RC2HL based upon what I saw on the scope. The strobe output looks like just power and a short positive pulse to trigger it, and conveniently enough, the FLASH output of the DBC-RC2HL outputs a positive pulse on the positive pin. It might need a 10k+ resistor to negative just to pull down the output and stop it from floating when unloaded. That's the theory anyway.

D.

blitzkrieg65

Great stuff David, its good to hear your detailed report!

I just want to make Clear that at right now you CAN add the DBC/DBU/SD the same way we have always done it, different conection points though! David is looking at using some of the components of the HL system! But the cool thing is that it will very easy to install your DBC IR LED because you already had in the tank, so you have a holder or bezel for it! And you have a landing for the DBU, just minor cuts and install the whole system, then you are ready too start whooping some Tamiya Butt

The Blitz

fv432

Like the sound of that one phil but as pete said haven't seen one for sale over here yet except for silly money[sm=spinnyeyes.gif][sm=spinnyeyes.gif]

Rob

blitzkrieg65

Just to make that clear you mean the tanks themself right? Because I know there will be at least 3 DBC/DBU/SD battling at Bovington this weekend!

The Blitz

fv432

ooppps yep meant the tammy tanks [sm=red_smile.gif][sm=red_smile.gif]

can't wait to see them in action[8D]
matt is hoping to get some video of the action[8D][8D][8D]

Planedev

Good to hear that, now, if only someone carried those strobes, will check if mato sells them too, if I can get a set I should be able to test it with my tank.

csal

Hi Blitz,

I just bought a Stug and the DBU/DBC/SD. If possible, could you show me how to hook it up to the new board?

Thanks,

Carl

blitzkrieg65

Hey Carl,

I will try to get a picture of where I connected to the bottom of the board, but David may beat me too it with some better points? If not I will post tomorrow afternoon!

The Blitz

971wright

Fast work from you guys yet again dont no how you find the time .


best regards pete

darkith

More notes:

Heng Long has done a much better job of wiring. They actually use Red for positive and Black for negative, and other colors for switched power outputs and signals.
Wiring is neater, fewer wires just tacked on any old place.

And as Blitz already indicated, both DBCs (the DBC-HL and DBC-RC2HL) work fine with the next TK-RX18 board.

The Heng Long infrared LED works fine. It's quite powerful as far as I can tell (****ty weather, so only short range tests). I used a 22 ohm inline resistor, though further range testing would indicate if dropping to a 10ohm resistor is needed (though it may burn up there) or increasing resistance is needed (if it's too powerful). The angle is too wide though...it needs a focusing tube to limit the spread...both the Tamiya LED in it's tube and the stock DBC IR LED have a narrower beam. Remember: "friendly fire....isn't"

The cannon flash can be hooked directly to the DBC-RC2HL "flash" output with the stock 10 ohm inline resistor.

Now, the HBU...that's different. When hooked up to a DBC, it can battle just fine with my Tamiya Sherman. But, it cannot receive hits from my DBC-equipped PzIII except at *very* short range (1-3 ft). It appears that the HBU is only sensitive to a narrow band of IR, and the stock DBC IR LED only emits a narrow band of IR. I suspect the HBU sensor is looking for 880nm, and I know the DBC IR LED is emitting a narrow band at 940nm, with very little (< 5%) at 880nm.
Both the TBU and DBU are sensitive to a wide band of IR (so can be hit by both 880nm and 940nm LEDs), and the Tamiya IR LED appears to be wide band and cover 880nm and 940 nm, though it's possible that the ranges would be different. (e.g. the range to hit a 880nm HBU would be different to hit a 940nm TBU, even if the optics were in the same condition). Unfortunately, I don't know how I could verify this, but the theory fits the symptoms.

So, for now, I don't know if I can recommend the stock HBU as a DBC sensor. It will work if you *only* battle Tamiya tanks, but I don't even know if the range is similar. There are two options though:
1. Replace the sensor inside the HBU with a DBU sensor (note the pinout is different, don't plug it into a stock HL). This means your tank will be able to take hits from anyone.
2. Replace the IR LED in any DBC equipped tanks with a wide band LED. This means the tank will be able to hit stock HBUs...but stock HBUs will still only be hit by "wide band" DBC tanks.

I really hate compatibility issues. For now, I'd recommend sticking with the DBU, or grafting a DBU sensor into the HBU....that makes the HBU wide-band for sure.

I'll post some notes and pics on my website documenting attaching to the RX-18 shortly.

D.

kclank

are you going to put the hook up instructions on your web site?

darkith

Brief hook-up instructions posted, follow link from: http://darkith.dyndns.org/~darkith/html/dbc.shtml
Will try to improve as time permits, but let me know if anything in particular isn't clear.

D.

borealis

Great testing work!

971wright

Dave the I.R. led You said it might be short on range if it was mounted in a tube to focus the beam would this improve it or would it be better to change it and put one of yours in a tube,or has it not been tested yet .will have to mount a tube so just want to know which led to use.


regards pete

darkith

Can't be sure yet Pete. The Heng Long IR LED might actually have better range, or less.
If you want to just get up and running, the DBC LED is a known quantity, so it would be the safest route. But hold onto the Heng Long LED just in case.

D.

971wright

Hi Dave have to fit tube will test range if its ok will stay with it if its short will change either way first mod will be I.R. tube to focus beam case of suck it and see.


regards pete

darkith

Sounds good, let me know how it works for you.

D.

mickyb

Hi folks, I have only just started on this hobby and have already been hooked, the boats have been consigned to the loft aready.

I am doing the prep work for a scratch built 1/16 Challenger 2, and the parts box is already filling up with bits.... incluing an HL RX18 board and associated cables.[8D]

I am ok with modelling, but I am hopeless with electronics....especially the understanding part....once you get past 60 it just doesnt make sence.

I am building a HL Tiger and upgrading it alongside the Chally work so the Tiger is a test bed for the electronics.

What I read here is quite amazing, will someone be putting together a schematic of sorts for us old gits to follow please.... ( ie what gets soldered to what? )I love putting these things together, time is not really an issue just the understanding part. I would be more than happy to send bribes or bottles of wine in payment!!!!!

I build everything for my boats, but I can see these tanks being far more electronically orientated so the old grey matter will get some excercise. I would love to get some extra volume from the sound components, will this upgrade you guys are working on lead this extra volume, or just the combat side of things. Perhaps there is an amplifier that I can wire in or do you just go for this EL-mod equipment.

I really would be greatful for your guidance as I dont want to go in the wrong direction.

Thanks fellas............. Mike

YHR

Hi Mike.

There is a wealth of information on this forum. All that you asked should be archived away in old posts. Try the search feature. It will produce volumes of info for you to read. These tanks are a real enjoyable hobby. Lots to work on, and you can just take them out in the back yard and run them. I built a 6 ft long aircraft carrier, but it is a shelf queen now. It was such a hassle hauling it down to the pond.