The Unnamed (FW)

[RogueTwoRobots]

Those screws take ages to remove/refit, especially compared to the modding process itself. I just cut the spare wire off with snips though now, shaves another few seconds off the process

[Pinski1]

Oh boy, it's been a while.

I took it to Burgess Hill, and managed to murder 4 OrangeRXs in <24 hours. After the 4th one (donated by some lovely beetle weight guys, THANKS!) I figured that the universe was telling me to give it up. The casualties:
(antenna mod on the right is my own work)

I've got the robot moving again under remote control, this time with a LemonRX receiver. I'm not 100% sure why the OrangeRXs kept dying. I was blaming the large arcing and sparking that happens every time I insert the removable link/fuse but I couldn't get voltage spikes of >7.2 Volts during testing which is just within the maximum voltage of an OrangeRX so they should have been okay. The LemonRX on the other hand has a maximum voltage of ~10 Volts so should be more immune to that kind of crud. Of course I wouldn't be an engineer if I didn't then go and design an over complicated way of fixing the problem, thus I present my eFuse:


It's approximately 50mm x 31mm x 7mm has under voltage, over voltage and over current lock out, with automatic re-try. It can be set to custom voltage/current limits. It will also soft start to stop arcing/sparking and prolong contact lifetimes. Still a bit more work to do but I'm hoping it'll be amazing.

Of course now I've fixed the receiver I find out that the mixer (GWS V-TAIL MIXER) is acting up, when connected to an oscilloscope it seems to do the right thing but when in the robot it starts acting funny. I need to do some further testing and may have to buy a new one. Although I could make one...

To distract myself from the non-working robot I've designed some snazzy lights to go inside the drive belt area. They are programmable and can run through some nice patterns, here they are during development:


And with the large 18V Dewalt motors I had a few months ago I started drawing up robot designs while at Newcastle Maker Faire and when I got back I laser cut one out of cardboard to see how it would fit together. Its inspired by Tormenta 3 as well as some interesting conversations I had with makers at Maker Faire.


The cardboard will be replaced with water-jetted Hardox ~3mm thick. Gives a new meaning to Cardboard Aided Design.

[tweedermeister]

The orange rx problems didn't stop after you left, I burnt out my other 2 on the 2nd day, I've made the switch to the lemons now as well but I haven't tested them in Ash yet.

[razerdave]

I'm glad to hear you got it working under remote, still can't fathom why it was killing oranges all over the place but I'd be interested to know the results if you find out.
As for the mixing, what TX do you use? I thought I saw you with a DX6i...

[Pinski1]

I'm glad to hear you got it working under remote, still can't fathom why it was killing oranges all over the place but I'd be interested to know the results if you find out.
As for the mixing, what TX do you use? I thought I saw you with a DX6i...

On the R620s there's a section of blown track next to the servo connectors on the underside, the pictures only show the tops but I'll try and get one of the bottoms tonight so you can see. My working theory was that the excessive arcing/sparking of me inserting my removable link/fuse was causing the switch mode power supplies of the Tz-85As to start up then stop then start up which lead to much higher than expected voltages on the servo +5.5V rail. That would then blow the receivers logic. But I could only get the voltage up to ~7.5 Volts when I was testing with an oscilloscope and dummy load. *shrugs* I do want to find out what happened because I don't want my LemonRx to go the same way.

I'm currently using a Dx5i and considering upgrading to something with programmable configs and also some provision for basic telemetry.

The orange rx problems didn't stop after you left, I burnt out my other 2 on the 2nd day, I've made the switch to the lemons now as well but I haven't tested them in Ash yet.

Sorry to hear that, I had a good opinion of OrangeRXs before that weekend, but now its shot!

[Rapidrory]

Have you cut the power line to the RX of one of the TZs; You should only ever have one BEC powering an RX, so ideally need to cut the positive wire to the RX from one of them. And the arcing is standard as the caps charge; most people will get this. If it's larger than normal than this is more likely to be a symptom of a problem than a cause. The thing I find that normally blows lemons is reverse voltage; they can't handle even the slightest blip of it where as Lemons don't care as much.. Might be worth looking in to..

[Pinski1]

Have you cut the power line to the RX of one of the TZs; You should only ever have one BEC powering an RX, so ideally need to cut the positive wire to the RX from one of them. And the arcing is standard as the caps charge; most people will get this. If it's larger than normal than this is more likely to be a symptom of a problem than a cause.

Oh I understand why it arcs/sparks but it does damage the contacts and should be avoided.

I've tried having the RX powered by one Tz-85A and I've had it so all 3 Tz-85As power the RX, it doesn't seem to affect it. Either way it's only powered off the one at the moment.

[RogueTwoRobots]

That's quite a number of wrecked receivers. It's quite a popular combination of electronics in featherweights though, the Orange RXs and TZ-85s. To the forum in general, has anyone else had a similar issue occurring?

[Eventorizon]

I managed to kill 3 RX's at the champs this year despite having only 1 TZ85A powering the RX, one I am pretty sure was caused by a short circuit though. The other two... no idea. I have been considering returning to a dedicated BEC like I had in C1 and C2 but it may have just been my wiring.

[Ellis]

Never had them blow back to back like that. Tormenta 3 uses an older orange (12-18 months) and TZ85s and it was fine, but I specifically used the older one as those purchased more recently (<12 months) have been unreliable; something lots of builders the world over are experiencing. My guess is manufacturing changes in later models, probably to cut costs, are introducing faults that older units don't experience.

[Rapidrory]

I recently fixed a TZ for someone where the main inductor for the BEC had come off the board due to excessive forces; TZs are designed for planes not fighting. My thought to battle harden them would just be to cover the signal side of the board with hot glue to keep everything in place and keep swarf out... But a separate BEC might not be a bad idea. Not using it for anything other than the RX so linear regulator putting out 0.5A @ 5v would be plenty enough...

Also, I use Lemons in all my robots from nanoweights to my Heavyweight and have never had one die in a robot (had a few dead from the factory and another few die whilst soldering them up, but I've bought over 50 so far so it's actually a fairly low failure rate... at ~£3 each it's not a huge issue)

[leorcc]

I dipped ours in plastidip to keep the parts in place.

[Pinski1]

Here's the picture of their undersides, I threw in an R710 on the left (the rest are R620s).

You can see the blown track in the centre near the pin headers on both R620s. It may also be wroth noting that the bottoms are almost identical, same parts, same idents just the R710 has more board area.

I'm not too sure what to do now. I need to mix 2 channels to control the motors and thus the movement but the Dx5i mixes so that left to right are forwards and backwards which is unworkable. I could shell out £10 for a new GWS Mixer or £10 for a Trinket micro-controller with a custom mixer firmware or buy a much more intelligent TX which can do it internally. I'm planning on getting into quadcopters so I will need a more intelligent TX eventually, but its a lot to ask for right now.

The rest of the robot wise:

• front arm of the lifter is now milled out of a solid block of aluminium, it's awesome!
• LED 'bling' is programmed, waiting on a mini micro-controller to run it as well as fitting it
• I have some anti-spark XT-90-S connectors and am awaiting a Midi Fuse & holder to see how it could replace my Maxifuse arrangement. This will stop arcing/sparking.
• I'm looking into my over complicated electronic fuse to see if it's a terrible idea or just a weird one.
• I still need to grind down the front lip of the robot so it's thinner.
• I need to ship the Hardox parts off for powder coating
• I need to fight in a competition

Nearly there...

[Pinski1]

Got it all working quite nicely on Sunday and even got a video of it!

https://www.youtube.com/watch?v=nKpjv4IiSTc
(Sorry about the vertical video, the camera man has been mocked)

I think my driving needs a bit of work and I'm finding having the lifter on the rudder stick a bit awkward to control.

The tasks remaining are:

• Figure out a mounting solution for the Midi fuse and XT-90-S
• Get testing the electronic fuse
• Finish mounting the electronics
• Ship the harddox parts off for powder coating

The next big problem is when's the next featherweight competition?

[Niels - Team K.a.L.M.]

looks strong, nicely done