Destroy It Yourself - a first attempt at a FW.

Hello all!

Sorry to ask what is possibly a stupid (and certainly un-necessary question). I have a Devo 7 that I'm looking to use as a transmitter for a featherweight. I've been following (to a degree) John Findlay's guide on his youtube channel but using a pair of Botbitz 30As as Speed Controllers for the moment rather than a Sabretooth - I have a LemonRX receiver but I'm running into the issues at the moment of mixing situations.

Most people I've talked to on the discord (Garfie, Shakey, Jarvis etc) have all said the best bet is to get a new controller that can mix itself but I don't know if I can stretch to that with my finances. I'm looking at a mixer, but none of the above have been able to give me a confirmed answer about what's a good option.

I know it's probably a bit of a stretch but if anyone can give me a hand, which one should I look at out of these two:
https://hobbyking.com/en_us/turnigy-...tra-small.html
https://hobbyking.com/en_us/turnigy-...lti-mixer.html

...or am I barking up the wrong tree with these? I once again realise this is not a great question that looks very professional, but this is being done on a budget, and as a first attempt.

Best regards

Greg

I've just ordered a ultra small V-Tail mixer for one of my robots and should be with me in a day or so so I'll be in a better position to advise as to wherever that works not.

Secondary mixing like this does introduce another element that can break, hence why transmitter mixing is preferable I should think (I rather sidestepped the issue by getting a transmitter that has proper tank controls). With that said, I am sure the Devo 7 can be flashed with new firmware to allow for mixing... someone with one might be able to clarify that mind.

I've used the ultra small mixer in my quad rovers, and they do work. https://www.thingiverse.com/thing:2687740

Everyone else is suggesting you buy a mixer, but if you are using a Devo 7, I don't think you need one. I'm using a Devo 7E myself, and after doing some research, it's perfectly possible to operate 2 wheel drive using one ESC. You just need to make a few modifications. Read up on these:

Rory's post alerting people to the Devo 7 series of transmitters, as well as info about the firmware needed to modify them with: http://robotwars101.org/forum/viewto...t=2387&p=56251

Userfriendly's guide on how to mix channels on the Devo, this should be what you're looking for: http://robotwars101.org/forum/viewtopic.php?f=10&t=2526

Hope this helps!

I bought a few mixers a few months ago after the trouble we were getting on UP-VOTE, i have a few spare. You know where we are if you want one.

The ultra small mixer works fine, as adamclark suggested. However, if it is available, I'd still go down the transmitter mixing route.

Hey guys, thanks for the input. Unfortunately it's not been a particularly good outcome.

I tried using the video in Shooty's post, and the second I did it, not only did nothing happen, but one of my Botbitz ESCs began to get very, very hot. Tried it with only one side and it worked fine, so I think I've managed to blow my ESC somehow. The motor works fine, but the receiver won't behave itself if I wire the broken one up.

https://cdn.discordapp.com/attachmen...5562/image.jpg

Go ahead and laugh - I got a soldering iron for christmas, turned out to be a shitty 8W Maplin handheld one, so I've been using screw connectors instead. This is how it's looked at the WIP stage wiring wise. Below is a picture of the ESC after Ellis told me it was alright to remove the covering to take a look - being an incompetent spud I can't actually tell what's wrong with it.

https://cdn.discordapp.com/attachmen...3707/image.jpg

Something's telling me I'm not cut out for robotics. :/

There is the possibility that either the battery is too powerful for it, which is unlikely given the other one works or the speed controller was duff upon arrival. Does a specific part of the controller get hot?

I wouldn't worry about using connector blocks, I use them deliberately in The Honey Badger to make swapping out components easier. They've yet to let me down.

It seems to be the black part in the lower right hand corner of the board. (by the orientation on the forums here at least - if stood up, it's to the left of the grey block that reads 220. Or at least, that's the part that burned me when I touched it).

Right. So you have 2 x Botbitz plugged into your receiver at the same time? Have you cut the power cable on one of the esc receiver plugs? It's common knowledge that both power lines going in overload most receivers. I learnt this the hard way 2 nights before an event and have stuck with dual speed controllers ever since. :/

what battery are you using and what receiver ?

Quote:

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Originally Posted by daveimi

Right. So you have 2 x Botbitz plugged into your receiver at the same time? Have you cut the power cable on one of the esc receiver plugs? It's common knowledge that both power lines going in overload most receivers. I learnt this the hard way 2 nights before an event and have stuck with dual speed controllers ever since. :/

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I hadn't actually been aware of this at all, though it's not a problem with the receiver - with the actual ESC. I think it's more to do with the fact that I had a difference of charge between them and maybe the problem had just been getting worse and worse until today it went. I think dual controllers will probably be where I go from now on. MY power source is a 12V Li-Ion battery from an Argos drill... I was only using the one, powering one ESC since I thought that was mroe or less sufficient and didn't think there was an issue with balances. Harsh lessons again, I guess.

Thanks to everyone for their input though. True stories for sure about roboteers pulling together, it feels good.

Good luck in your future building, and sorry to hear about the ESC, can't help but feel a little guilty for that :(

Please don't, it's not your fault - it was entirely mine. Money's tight (when is it not with robotics) so I'll have to put this on the backburner. Time until Manchester at least. Dave's offered his workshop and some time, I'll have to see if I can get up there though.

If anything this has been massively helpful. :) I don't mean to dissuade others from asking for help from Shakey, Garfie and Jarvis, but you guys have been really helpful and pinpointed a lot of issues they couldn't, so I appreciate that. I'll definetely keep you updated and here's hoping I do end up with D.I.Y. at an event!

I'm going to Manchester so if you need any help give me a yell.

I will also be at Manchester with my floatilla of robots so yeah, if you do need a hand, come and find me.

Attachment 7632
So for what might have sounded like a bad ending, a replacement BB30 turned up and I plucked up the courage to keep going. My soldering is beyond horrendous, the connections are flimsy as heck but by god it works - it's mixed right too. I will probably have to trim it, but just to give everyone on here a heads up and a thanks for your help. :) Once I've made a chassis I'll head to Manchester and hopefully see you guys there!

Looks good, make sure you cover up your soldering though, don't want to risk a short circuit. ;)

See you in Manchester. :D

It lives!

https://www.facebook.com/gregory.atk...10339569715999

Now I just need to put it into a proper chassis, clean it up, get real wheels... but man, nothing is quite like seeing it work the first time. :)

Reminds me of the first time I got the first version of my featherweight going, good work :D