It's been so very long

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antrock101
Posts: 18
Joined: Fri Jun 27, 2008 6:43 pm

It's been so very long

Post by antrock101 »

Hello all,

I doubt many of you will remember me but I was a member during the earlier years (around 2004) I only competed a handful of times. It's so great too see this site is still thriving and the technology improvement is unbelievable. The days of cardboard with 2 rubbishy servos maxing out at 150grams are long gone!

Reason I logged back in is, I am all grown up now and became a computing teacher. I'm desperate to get these kids into robots and electronics as they seem to enjoy it. Lucky I'm writing a paper on computational thinking and have the opportunity to get 5 kids making them. Unfortunately I have to soak up the costs for this.

Can any point me in the direction of cheap kits and parts quality doesn't matter, I want these kids to learn and explore but with school budgets so low this is impossible. I have over 200 kids a week with a budget of just under a grand a term, crazy right. So it's out of my own pocket, I'd love some advice!

PS ... All my old posts are missing any reason???
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joey_picus
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Re: It's been so very long

Post by joey_picus »

Hiya! I'm from far after your time unfortunately (you should see what we can get into 25g now...), but I believe I've seen quite a few of your robots on videos from the past, and of course getting new people into antweights can only be a good thing :) here follows a long and rambling answer...

If it's school budgets you're working with, until quite recently Technobots used to sell some Guan Li "Sky Sport 2" 27 Mhz transmitter/reciever kits with built in motor drivers; although these only powered the motors forwards (so turning was sort of possible, but no reverse) and you couldn't change the crystals, they were antweight sized and ludicrously cheap (I think they ended up being reduced to £3 each!), so it might be worth hunting around for something similar, or emailing Technobots to ask where they found them. Worryingly, I used one in a robot largely made of furry Easter chicks and it got quite far in an AWS...

Failing that, for a competitive antweight these days unfortunately you're looking at about £60 minimum in parts each :( so for a cheap, kid-friendly kit of parts you probably need to go back in time a little. Modified servos would still work as drive motors; the SG90 is quite fast as standard, easy to speed modify (see if the kids can work it out for themselves!), fairly robust, and most importantly very cheap in bulk quantities. I'd imagine if you kept the battery voltage and current quite low (i.e. 4.8v NiMh/NiCad rather than LiPo - I can't imagine the risk assessment you'd need for LiPo...) you could *probably* get away with using the boards, suitably modified, as speed controllers for the 12 x 10mm micro gearmotors that are universal in antweights (and have a quite useful ecosystem of parts around them), but I wouldn't necessarily quote me on that!

Combine those - either using the servos as motors or the boards as speed controllers (and some as weapons, of course!) with the cheapest possible 2.4 Ghz radio system (a LemonRx 6 channel DSM2 reciever - here, although I am almost certain you can find them cheaper - with one of the Blade MLP4DSM transmitters that come up on eBay, although those are Mode 1), some small NiMh batteries, a reciever battery charger dug out from all those years ago, some materials from the scrap cupboard and B&Q and the ingenuity and creativity of children when faced with an array of interesting parts and a challenge, and you might be in business for relatively little money! :)

That's how my train of thought worked, at least; given the time I'm writing this, someone else will come up with a better idea probably, but that's one way of going about it. And good luck with the venture, and if you find the time to get down to an AWS sometime you'd be made very welcome :)
Joey McConnell-Farber - Team Picus Telerobotics - http://picus.org.uk/ - @joey_picus
"These dreams go on when I close my eyes...every second of the night, I live another life"
Rapidrory
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Joined: Sun Nov 24, 2013 9:54 pm

Re: It's been so very long

Post by Rapidrory »

Hi, welcome back :)

The standard radio setup used in all weight classes these days is DSM2 2.4GHz. As Joey said, the cheapest DSM2 setup is currently a MLP4DSM Blade Transmitter, which can vary anywhere between £7 and £40 on ebay depending when in the year you buy them; currently on about £15 it seems, and the Lemon Rx for £4 (Buy them from here, NOT ebay unless you want to be ripped off. http://www.lemon-rx.com/shop/index.php? ... duct_id=93)

A few ants still run SG90s, there servo boards are fine driving the standard gear motors. Joey's motor suggestion was from pololu which is very expensive. It is much better to buy in bulk from china for £2 each: http://www.aliexpress.com/item/N20-DC-G ... 08477.html . You'll need to ask for the 6v 500rpm ones.
Motor mounts are also really cheap (£1.50 for 10) and can be found here http://www.aliexpress.com/item/F05101-1 ... 91685.html
Good grippy wheels for these motors can be found here(~£2.50 each): http://www.technobotsonline.com/pololu- ... -of-2.html.

NiMH are probably going to be your easiest be: These guys have a fairly good selection, this is just one option: http://www.componentshop.co.uk/4-8v-1-2 ... -pack.html

Total cost of electronics per robot would be about £20 per robot not including the transmitter (£35 per bot including TX). Does mean you have to do diagonal drive steering though.

Alternatively you could buy the competitive electronics kits for £40 each (https://docs.google.com/document/d/1feH ... Qi4Kc/edit#). Some schools do buy these in bulk for students to use, but it depends on the budget.
Rory Mangles - Team Nuts

Robots: Nuts 2 and many more...

NanoTwo Motor Controllers: https://nutsandbots.co.uk/product/nanotwodualesc
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UserFriendly
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Re: It's been so very long

Post by UserFriendly »

Having built my own, using hacked servoboards v-tail mixer and FM radios, and then bought Rory's kit (last link on his post above), I would say just get that. £30 for the receiver and ESC built in. Obs. you will need transmitter, battery, motors and mechanics, but his kit (I think he undersells it above!) saves A LOT of headache! Get the kids to the fun ASAP, that's what I'd say!
Andy B - Team UserFriendly
Reading Cybernetics Graduate 1996
Trying not to take Antweights too seriously. I think I'm failing.
First AWS was 46.
antrock101
Posts: 18
Joined: Fri Jun 27, 2008 6:43 pm

Re: It's been so very long

Post by antrock101 »

wow 2.4ghz it was 27mhz back then! , being competitive is not an issue, they wont actually enter anything just want them to know what you can do when you use your mind and a little bit of knowledge. I want to them think about competitive bots. Looks like the main problem will be RX and TX and the price. I can probably stretch to buying a few Chinese motors and using the SG90 boards as speed controllers or modding the SG90's for 360 rotation (i presume this is an easy hack?) batteries I can use AA's or 9V until they are ready to upgrade.

Anyone know of anywhere I can get educational discount or second hand items for cheap in bulk or as singles?
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BeligerAnt
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Re: It's been so very long

Post by BeligerAnt »

You could try asking some of the larger real-world model shops if they have any second-hand gear they could do a deal on. There's no reason not to use 27MHz or 40MHz gear and I can't imagine anyone would want much money for it these days.

You could also try sending a PM to PeteC to see if he has any good sources.

Avoid PP3 9V batteries, they won't work well. You could use 4 x AA or AAA alkaline. If you're not worried about entering any "open" competitions you could "adjust" the rules slightly - say 100g or 125g excluding batteries. It's worth keeping some sort of size & weight limits as they provide some constraints to add to the challenge.

Good luck with the project - let us know how it goes!

P.S. Regarding old posts. The forum got hacked a long time ago and all the old posts got lost as part of the rebuild. I can't remember when this was, but it's the only reason I can think of that posts would be missing.
Gary, Team BeligerAnt
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Shakey
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Re: It's been so very long

Post by Shakey »

Considering a LiPo setup is £5 there's not much reason not to stretch to one.

Also I built a PP3 ant last month and it worked fine as long as it had a good quality one in!
Nuts And Bots - For all your components and ready built antweights!

Alex Shakespeare - Team Shakey / Nuts And Bots / Team Nuts:
AWS 44, 45, 49, 51 & 55 Winner - Far too many robots!
antrock101
Posts: 18
Joined: Fri Jun 27, 2008 6:43 pm

Re: It's been so very long

Post by antrock101 »

Thats some good ideas, I'll try and get hold of some old 27mhz gear if I can, and recommendations for easy to mod servos or very cheap esc?
antrock101
Posts: 18
Joined: Fri Jun 27, 2008 6:43 pm

Re: It's been so very long

Post by antrock101 »

quick question, with 2.4ghz will any receiver pair with any transmitter on the same range if they both use the same crystals, seen some cheap sets on a Chinese site and wonder if they can be expanded on in the future.
Hogi
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Re: It's been so very long

Post by Hogi »

i think most of us nowadays use transmitters with DSM2. model names that have it include Eflight, blade, orange and spektrum. that's just a few, there are probably more than that with it. A transmitter with DSM2 will bind to a reciever with DSM2 making the models effectively cross compatible. someone else could probably give a more detailed explaination but that's my understanding of it.
Daniel Jackson.

Team Hectic.

Many antweights

Super antweights: territorial.

Fleaweights: fleadom fighter, gaztons.

Featherweights: hectic (under construction)
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