Ummm... cheaper speed controllers? Please? :)
Printable View
Ummm... cheaper speed controllers? Please? :)
There are tons of threads talking about the merits of each type of speed controller, just have a look through the featherweight section. Botbitz are probably the best value for money/cheapest esc other than the problematic eBay ones.
I've managed to buy some of the problem 1s off ebay recently just properly tested them and the stop when shifting from full forward to revers, im gonna dismantle them and see if there are any component differences between the previous 1s i bought that work and the newer version
ive also ordered some more from a different suppler to test out probably wont see them till the end of the month but i can post up the link if they work
I know you are trying to do everything on a budget but their are certain things you can see as an investment or that are not worth going cheap on, the Transmitter and Receiver is one and ESC's are another.
A good Transmitter is something you can use for years and on many, many machines. Thanks to DSM2 you could own an antweight, a beetleweight and a feather and since you will never drive them all at the same time use 1 Transmitter. So the cost can be split over 3 machines. But the key point is that you will be spending £250+ usually more on the machine and if your £25 transmitter fails then that could easily be your £250 gone in one swoop. A DX5 is about £70-90 and will last years if looked after properly.
ESC's can make or break a machine as it is the single part that will have the greatest effect over how your machine drives. A good ESC can take a mediocre machine up to something that can out drive and manoeuvre some of the big players in the game. The hacked TZ85A transformed Conker 2 and Made driving Binky so much easier. Ellis was raving about the improvement to Tormenta 2 at GSL. Use the right fuse and ESC's can last you several machines (My TZ85A's went briefly in Conker 1, Did GSL in Conker 3 and are now going into C3) if set up right and make your life a whole lot easier when it comes to driving under combat conditions.
Over a year. It's been over a year since I last made any effort towards even thinking about building a robot. Well, I want to say I haven't ever given in completely. I've kept up to date on YouTube and read a few posts on here. Nothing much, but I haven't completely given up.
Anyway, yes I'm still here. Yes, I still want to build a robot. No, I haven't really done anything yet. I've made excuses to myself already and now I'm more determined than ever. I've bought a crappy, cheap soldering iron which won't last me but it works at least and, as ever, I have a few questions:
If my battery is rated 2650mAh with a c-rating of 20-30 than my max current amp draw is 79.5A (i.e. 2.65A x 30), right? But, according to razerdave from a year ago, I shouldn't be pulling anything like that. Apparently I need a fuse rated for around half the max amp draw, right? So, around 40 or 50 amps?
And then, what about wire? It's a fundamental part of a robot which nobody seems to mention on here. What sort of wire do I need that can handle 40 to 50 amps? I've gone a bought some crappy 7-0.2mm wire from Maplin and I've realised that's not going to cut the mustard. The website says that wire can only take 1.4 amps. Am I going to need some pretty heavy duty wire, like the ones coming out of my tz85as? Where can I get some?
One final thing - what's the name of that red plug that most people use for their removable link?
I've come to realise that it's better to ask stupid questions than to sit like a lemon because you don't know the answers and that the value of my equipment is really in the experience, even if it's just the experience of building something and wiring it wrong, rather than in the equipment itself. I'm now willing to build a robot or break stuff trying.
12 awg silicone wire comes with the Tz85. get it from ebay or component shop or hobbyking. Red plugs are probably deans plugs. Ebay or hobbyking.
My featherweight uses 3 argos drill motors (two for drive, 1 for the weapon) all running off a Zippy 3 cell 2.2Ah 25C battery (http://www.hobbyking.co.uk/hobbyking...arehouse_.html). It gets quite warm after a long fight, but I've only recently blown the 30A fuse in it (upgraded the fuse to 60A as a quick fix for the event, but really need to downgrade it to 40A or similar). You should be fine on a 40A fuse or there abouts if you're only running 2 drills on a 4 cell battery.
I use a random mix of cables, but they're all around 12 awg. A good rule of thumb is to look at what size the cables coming out of the battery are and go for something around that..
I use XT60 connectors (http://www.hobbyking.co.uk/hobbyking...dProduct=46611) for my powerlink/ other connections. As it's the same as what's on your battery, it makes sense to use it for the rest of the robot.
You may have seen this already, but no one seemed to have pointed it out on here; TZ85 ESCs are brushless ESCs, so won't work with drill motors without being reprogrammed first. I believe you can get them pre-reprogrammed on some websites, otherwise you'll need to get someone to reprogram them or do it yourself. Someone with more experience double check this; I've never used them myself, though I have heard/ seen that they are pretty much bullet proof.
What parts have you got so far out of interest?
2650mAh 20-30C 4s Li-po battery
Two Botbitz TZ85a ESCs (these hacked ones do work for brushed motors, according to the manual)
Two cheap Argos 12V drill motors
Spektrum DX6i transmitter and AR6210 6-channel receiver
10mm- and 12mm-thick HDPE
Also looking at:
125mm diameter plastic-centred wheels with solid rubber tires (wheels are big because I'm going to go invertible): http://www.bearingboys.co.uk/BZMM125...e_Wheel-8716-p
50W li-po charger (I know I also need a battery bag): http://www.hobbyking.co.uk/hobbyking...arehouse_.html
Ah ok you got some pre-hacked TZ85s; those'll do you nicely :)
You won't get much grip out of those wheels as is; they have a hardness of 85 Shore A acording to the datasheet (https://www.bilcastors.co.uk/images/...12_114_115.pdf) which is pretty hard as things go (http://www.smooth-on.com/pdf/durometer_with_logo.pdf). You either want something around 30 Shore A, or just get those ones and screw bike tread to them using wood screws, which is what a lot of people do to add grip; my feather has wheels just made of plywood wrapped in bike tread which works fine! It would also add some extra diameter to the wheels which might be useful; make sure you have at least 10mm ground clearance around the wheels, or you will spend all your time stuck in potholes in the arena floor caused by the heavies!
Charger looks fine; I use a cheaper version of that and haven't had any problems with it.
The rule for batteries is that it must be fused for below your maximum discharge of the battery (I think), I'd give this plenty of leeway though, especially if you're going for a Turnigy pack or something. Whilst it is part of the rules, the last thing you'd want is to overdischarge your battery and cause yourself a fire because you don't know what you'll lose in doing so. That said, drill motors don't draw too heavily, I know robots that have used 2 drills on one TZ85 and they've been fine on those.
Drill motors technically draw 85A on stall I think but as long as you don't keep it on stall if you have a broken motor, you'll be fine. Mounted correctly too, the ESCs are pretty resilient to most things. Battery-wise, that sort of capacity sounds fine. Could probably even upgrade that if you really wanted, depending on how much weight you've got left - might be handy if you want to take part in more side events at the FW champs, for instance. Not sure how often/long the feather fights are at the Heavy events because I haven't been to one of those yet...
Have you got a design planned out for your machine, at all? Might be handy to post something, even just a Microsoft Paint diagram of it so people can probably try and advise further!