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Thermionic

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About Thermionic

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  1. Outstanding pictures. I also have one of these great cars, and like you I was more interested in building it than running it. I am also attracted to the larger version because of the engineering values in it. But as I am not interested in I.C. power, I can’t justify the cost for just another ornament to put on a shelf. My own DEX410 is serial no. 444, though it is one of the first versions which I built in October 2009. I have not updated it, though it has most of the tricks and mods incorporated from another forum. Fitted out with ‘standard’ Spektrum mini receiver, Tekin RS Pro ESC, 10.5 Redline motor, Thunder Ace digital servo and LiPo cells, the electrics were also an interesting build. My revival of interest in rc cars came from the reissue of the Buggy Champ (I had an original Sand Scorcher), and having built that car from the dawn of the off-road model car craze I though it would be interesting to sample the current state-of-the-art. The Durango is of course much faster than the SRB (even with an Orion 19t motor, racing ESC and ball diff) and, as is often the case with performance road cars, is far easier and more satisfying to drive. Now I am wondering about the impending Avanti reissue, though that would of course be a bit of a step down from the 410.
  2. This evening I had a modest bash around a rather wet garden with my modified Buggy Champ - lots of spins and hanging the back out. It’s fun but perhaps a bit too unpredictable (for me), so also today I have been adding some finishing touches to the rolling chassis of a Durango DEX410. This should prove an interesting contrast to the Tamiya.
  3. Right, further to the overheating problems with my Novak GTX running on part throttle settings in the BC (for just cruising about - see previous posts etc), I have at last hopefully sorted this out. Unfortunately Novak don’t seem to provide an add on fan for this lately discontinued racing esc, and what is available would seem to be too large and not easily fitted. A fan anyway would to some extent reduce the running time, and so I thought about fitting some extra heat sinking similar to that fitted to my now defunct Tamiya TEU-101BK. After rummaging about in my box of junk PC boards I found an old chip cooler with some nice long figures on it. This I cut down to fit the limited space available in the BC electrics box. I knew there was a reason that I had not put back the on/off switch in the box lid as the heat sink could now extend into this area. My modified new heat sink was simply glued with heat conducting epoxy to the top of the existing GTX heat sink, not pretty but functional. The end result being that I can now cruse around on resistive surfaces such as grass for periods of 20 minutes or more without the esc temperature rising much above 60Deg C. Before addition of the new heat sink it was reaching 85Deg after 10 minutes. Cheers T
  4. Yes, I would like something better than the Carson pack as I suspect the internal resistance of the cells is not as low as it could be. Making up a better pack seems a good idea. I am not a RC modeller really but had a Sand Scorcher back when and am on a nostalgia trip. In standard trim the only significant issue (apart from having to pack out the front wheel bearings a bit and other minor things commented upon on various forums) is I think with the Tamiya esc supplied. It works pretty well of course but the brakes seem non-existent with the heavy BC. But rather more importantly, because of the closed electronics box I presume, the esc is liable to run hot. This may only apply to 7.2V powering in the UK version, but my Spektrum radio sensor registered over 85Deg C on the black metal plate before I decided to stop and let things cool down. Of course the mosfets in the esc can stand a junction temp. of around 150 Deg C but 85 at the outside of the heat sink looks a little too hot to me. It might just be my wimpy driving and the Tamiya does have thermal protection, but it might be worth keeping an eye on it. I am even having trouble with an uprated esc, but how to ventilate the box without losing water resistance etc? Cheers T
  5. Ah mark ups! In a previous life I used to be in purchasing and nothing surprises me. But people have to make a living, and by the time most things have gone through an importer, a wholesaler and then the retailer, twice the ex-works price to the end user is not unusual. I used to pay £100 each for shock absorbers until I found who actually made them and then paid £20 from their wholesaler. One of the biggest mark-ups is of course with watches, but that’s another story. Well, I managed to do some driving of the Buggy Champ with the new set up (Novak GTX esc + Orion Method 19x2 motor) and thought I would report back. On the whole it’s pretty good, at least compared to how it was. The power seems more than enough (for this driver) and keeping it down / managing the wheel spin means that to make the thing drivable I have to limit the throttle to about 60%. At full throttle with the 6.5 to 1 taller gearing option the motor will rev to 26,000+ RPM (4,000 at the axle - no load). So it might pull perhaps 35+ given enough room. The big gain of course and almost worth the effort, is with the braking. The drag brake option in particular (throttle Profile 6 drag brake set at 40%) make the car respond like a classically tuned performance car (with no turbo). In that when you take your foot, er finger off the throttle the speed is instantly hauled down. It is a great contrast to the standard esc supplied, and goes a long way to removing the need for reverse (at least outside). Unfortunately, the down side is that the GTX has to work harder at keeping the speed down. And because of the small heat sink fitted in combination with a closed electronics box means that I am back to the overheating problems experienced with the Tamiya esc! (I would be interested to hear from other UK BC users if they have been getting thermal shut downs with the 7.2 V battery packs - and if not why not!) Disappointing this as I had hoped that something with a rated current of 150 amps would hardly notice having to keep the Orion motor going at around 15. And again I am having to think up ways of getting rid of heat without loosing environmental protection. Novak don’t seem to make an ad-on fan for the GTX so I am a bit stuck at the moment. I am reluctant to cut holes in the nice Tamiya electronics box but I am now beginning to see why later models didn’t bother with it. Cheers, T
  6. Yes, sure of course you will trash the GTX if connecting it in reverse to another esc. What I have in mind is to take the motor wires from the Novak and put them into some form of change-over switch operated by a servo (and after any additional diodes). So that the pos. and neg. wires can be swapped over before they connect to the motor (the esc doesn’t mind which way round the motor is). The switch would have to have break-before-make contacts of low resistance, but providing the esc is in neutral when the change over switching takes place I doubt it will be damaged. But it’s only something to ponder about as I get used to the current set up. Reverse is for wimps! T
  7. No, apparently as the GTX has a 36A one built in and 'does not require an external one under most conditions' = heavy braking lap after lap or low turn modified motors. T
  8. Hi guys, Live Steam Mad - Thanks for the info on the soldering I hate the modern lead lead-free stuff. Ah, I paid rather more than you for the Novak though perhaps mine is shiny new. I haven’t yet found any simple guide regarding the options (brake freq., dead band, min. brake etc) as what comes in the box is not that informative. A lot of the settings seem the same between profiles and I expect some trial and error is needed before I get my head round the real differences (currently using profile 6). Thanks for the info on the Nosram, perhaps for the next car. Oh well on the motor, but it was interesting getting the Orion in and it’s all done and working pretty well now. Perhaps not a beautiful thing but that motor cover was machined from delrin stock to fit motor and casing exactly, it‘s much stronger than the Taniya moulding and should keep the scenery out. My GTX came out of the box with a heat sink (but perhaps still too small for extended running in the BC). It seems to be directly bonded to the mosfet output pcb with a white conductive glue. Well it’s a nice little switch and I am thinking of doing something for the cooling where the Tamiya one went. Good point on the diode. I have in mind just swapping the output leads of the esc to the motor using something like a servo with some low resistance switching on it. A bit like the mechanical speed controller of old. I believe they do such things for boats but they look a bit current limited. The Spektrum has a third aux channel, so to reverse you would switch to aux on the handset, turn the steering wheel and then a dab of throttle - or something like that. - the fun would be in engineering it. No good for handbrake turns, just backing off objects perhaps. Badboy / Loaded - you are of course quite right, but I like to play. Cheers, T
  9. Well, and with respects and apologies to the purists, I am afraid that I have been playing with my Buggy again and hope this long post might be of some slight interest. With one of my passions once being for fast (ish) cars, I tend to think in terms of driving rather than modelling, and one of the fairly obvious aspects of the Buggy Champ to me was an almost total lack of brakes. (I drive mine mostly on grass or gravel so the locked diff is probably more of an advantage than a problem.) With my original Sand Scorcher of many years ago I eventually fitted a Demon 2 esc which naturally made the car more drivable but also provided a good amount of braking. So I thought I might try and do something about this new machine, and perhaps at the same time boost the performance a little. Trouble is these days to this newbie like me there is mind boggling choice in how one can power an electric rc car. I suppose the obvious thing to do is to get some sort of brushless set up and be done with it. But as we know, the motor mounting arrangement in the BC is specifically made for the standard 540 form factor motor, and nothing apart from that or its tuned variants will fit. Through my avid reading of various forums I also got the impression that a brushless system might not necessarily provide the best brakes. More confusion set in, and there was not much help from the various manufacturers web sites, as they seemed to have little hard information about their products, especially for someone attempting something different.. It was though becoming obvious to me that most if not all brushless motors have the winding exiting via a pcb at the rear end, and therefore would need some hacking about of the BC’s motor moulding or gearbox casting to fit. So this inclined me towards a good brushed system, perhaps using a performance 540 variant motor. So what esc to buy that would have good braking? Well I kind of made a mistake and ordered a Novak GTX. in error! I had narrowed things down to a LRP Quantum Pro 2 (I think) as it seemed to offer racing type performance, good breaking with reverse. But I also came across the Novak beast, with its advanced brakes and programming features at what seemed a good price. So ordered one, not realising that as a true racing esc it would not come with reverse. As the tuned Tamiya 540 motors seem difficult to get at the moment I plumped for a 19x2 turn Orion Method, because I was advised that this should fit the BC and give a good improvement in power. It was £20, so not a complete disaster if it didn’t work or fit, not like the GTX… Well you can fit an Orion Method in a Buggy Champ (images below), but you do have to do quite a bit of work first. The motor can fits in the gear case, but you have to remove the label. You then have to grind about a millimetre off the spindle at the pinion end. The brush holders need to be removed, have both their tabs taken off and about half a millimetre ground off their outside edges (so they can’t short out on the casting). The aluminium wings under the brush holders need grinding to fit the extra caps required for the GTX. And two caps need to be soldered to the can, but there is no room so you have to use the space where the can tabs fold into the end plastic moulding. You then have to discard the Tamiya clear plastic motor moulding and make or find a suitable waterproof cover. And lastly, properly retain the motor in the casting with a three millimetre screw from the pinion end (probably two of these would be best). Oh and lastly again, directly wire the esc wires to the brush solder tabs. I decided to keep the non-reversing GTX mostly to see what it would be like with the Orion, and hopefully being able to stop would remove most of the need for reverse anyway. The GTX installation was a lot more straight forward than the motor. The unit is tiny and just needed to be positioned with regard to the thick wires and being able to get at the programming button. I kept the supplied Novak switch, not bothering to graft on the Tamyia slider. The bec is a well regulated 6.3 volts, so the Spektrum battery volt meter is pretty redundant. The alarm though can be set so that once the volts dip below regulation the alarm goes off. Another effect of the new esc was that the Spektrum rev-counter went even more manic than usual and was giving some even dafter readings. But I had used non-screened wire to connect the optical unit to the receiver (Spektrum use an un-screened ribbon cable - might be something they should look at) and it seemed obvious that all sorts of pulses from the esc had been getting into the counter’s front end. So I replaced the sensor wire with some miniature 3 way screened (black wire to the screen) and suddenly I had a perfect rev counter and speedometer. No meter needle jumping about any more, just a steady and apparently accurate indication of speed and revs. I have only had one session with the new setup so far but the differences are obvious. Acceleration and top speed are of course noticeably improved, with the problem now being getting the power down and keeping the car in the wanted direction. No wheelies yet, but what braking! Just like in a real car; lift off the accelerator and the car instantly slows, slam the brakes on and the machine comes to a pretty quick halt. No locking of wheels, but I have yet to get to grips with the subtleties of the GTX’s programmes. Very promising stuff and the new set up seems to give longer run times as well, in that I was getting about 29 minutes running with the previous system and for the first run of the new one I got over 35. Nothing is perfect though as the GTX heat sink at the end of the run (35 minutes in the closed box) was at 85 Deg C, so I might have to do something about that. Lack of reverse remains a slight inconvenience, so I might investigate using the aux channel of the Spektrum to actuate some sort of reversing of the esc output. Not real problems but interesting things to ponder about Another lengthy post I am afraid Cheers, T
  10. Many thanks Live Steam Mad for your comments about the Tamiya esc and its marginal braking efficiency with the BC. All interesting and thought provoking stuff. It looks like at some point I need to find a not too rabid (low max RPM/KV rating) brushless system, and somehow shoehorn the motor into the gearbox casting and end moulding. Or perhaps on the other hand simply fit a ‘Sport Tuned’ 540 brushed motor and a much better esc. looks like this will be my next little project with the buggy. Thanks, T
  11. Thanks for the welcome and kind remarks guys, I expect I will just lurk mostly. I think you are right Live Steam in that the plastic moulding is the same as the ones made in 1979; it IS a 79 bumper. But I agree that the metal rod is different. I seem to recall some plating flaking on my old SS bumper rod, though can’t recall what was underneath, These new ones look to me like they have been cut from what I think is called ground stainless stock. Ah Wandy, I have a sinking feeling that the lock on my wallet is not strong enough as I have already been poring over brushless motor and esc specs. I know I don’t need this technology as it would seem even to this newb that the 540 supplied is a pretty good compromise for my casual use. But I had an up-rated motor in the SS years ago and that made it go very nicely but perhaps more importantly stop much better. The braking in the BC seems fairly non-existent at the moment. It may not apply to RC cars but having good brakes in a quick road (motor) car to me is equally important as good acceleration. So I imagine something with fewer turns would when shorted out (I assume that’s how it’s done) by the esc, haul the speed down quicker. Or at least that’s how I recalled my old set up with the Demon esc did. Am I correct in this gents? But whatever I went for I would still have to make it fit the BC’s gearbox and plastic cover as I would like to retain the waterproof aspects of the car. So I suppose a ’Sport Tuned’ 540 is the sensible option, and anyway there seems a mind boggling array of brushless motor systems out there to chose from (and to get wrong - help). Ho hum, the 540 is perfectly adequate, it is perfectly adequate, perfectly adequate. Cheers, T
  12. Hi everyone, respects and greetings to all. Hope you don’t mind a rank newbie posting some comments and a few snaps of his own variation of this great nostalgia trip. Like many I also had a Sand Scorcher when it first came out, and had much fun trying to improve it with things like a rear anti-roll bar, a self-adjusting rear wing (that varied according to steering position), better motor and a Demon esc, but when that blew up I later gave the car away to the son of a friend (!). Thirty years later and we have just moved to a place with a large garden, and was thinking it might be fun to get a tough radio controlled car to play in it with when by chance I discovered the re-issue. Bravo Tamiya problem sorted! So having pre-ordered a Buggy Champ I needed to get some electrics for it. As I probably wouldn’t be doing this again for a while I thought I would look for an interesting radio and eventually settled on the Spektrum DX3S system. Being interested in radio technology I liked the apparent intelligence of this system together with the ‘duplex’ telemetry and large lcd on the handset. So, I also use a Spektrum radio with the BC, though being old and used to sticks am not sure about the look or feel of the TX - perhaps with my Darth Vader costume on I will feel more at home with it. Anyway, the BC kit itself looked as far as I can remember virtually identical to my original srb rolling chassis apart from the few minor changes already noted by others, and I had some serious deja-vu putting the machine together, hardly needing the instructions. I also found that the front wheel bearings were a bit narrow for the stub axles, and my own fix was to place a ring of 20guage solder in the corner of the bearing well to space the inner bearing away from the hub centre. The loose (always were I think) rear shock absorber top mounts were fixed by a bit of duck tape wrapped around the roll bar before clamping the castings on. I liked the idea of knowing battery volts and esc temperature as well as having a rev-counter on the handset, but found that the optical sensor position was fairly critical and a special light proof mounting seemed to be needed. In the end I milled a small alloy box out of the solid and chopped away the area around the motor pinion on the clear plastic cover. Painting that area black I replaced the sensor’s ribbon cable with some thin but tough headphone wire. This was threaded through the existing rubber esc wire grommet into the electronics box. (You don’t have to cut this grommet to fit it if you remove the soft plastic bullet connector covers from the esc wires first.) BC Tacho Mount Frustratingly the ‘needle’ on the lcd remains fairly erratic (perhaps some revised firmware is needed here), though the MPH option seems to be more stable. But I wonder how you are supposed to drive the car while looking at the Speedo, as my car usually ends up in the scenery! However, with the taller gear option fitted an indicated 25 MPH is displayed on the handset at full throttle. For the receiver I thought it would be a good practice to take the short aerial wire straight up and out of the electronics box. The Specktrum reciever was placed in the original RX position and the antenna tube mounted on the centre line of the car. I had to remove the bottom case half of the RX to get the connectors to fit, and also mod some of the connectors, but the unit works fine just retained with a simple foam block. A slight problem was that I now needed to re-route the stering rod, but with a bit if bending this seems to be ok now. As regards flexibility issues with the servo mounting (we happily used tape way back when), the steering I imagine was never that precise on this model, but probably perfectly ok for careering about on sand. BC Ant Mount I fixed the temperature sensor on the esc heat sink as I was interested to see how hot this would get. The Tamiya unit was probably designed to be mounted in the open but now of course it’s in a virtually sealed box. The rest of the electrics consist of a Prolux 5009F metal geared servo and a Carson 7.2 Volt pack. The first run seemed fine apart from the esc reaching 85 deg C after about 15 mins of fairly hard running over grass and gravell. Would this become a problem? The esc had not cut out and MOSFETS can take more than this of course, but the temperature was not heading in the right direction.. So I hacked a chunk of aluminium about to give some more mass and surface area, and bonded this to the esc heat sink with silver thermal epoxy. This seems to lower the temp by about 10 degrees C. BC Heat Sink The last couple of small mods. are to the body. As I don’t want to worry about damaging paintwork or those spot lights when bashing about I have left the body un-finished and in the white but with a few relevant stickers. But as the body helps with chassis rigidity I did though re-enforce plastic at the fixing clip hole at the front, and I also made a sacrificial ‘hat’ over the roof to give some protection when rolling over. BC Front Mount BC Complete
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