Rigging A Failsafe

[jim]

Failsafes are not a particularly expensive component, so I imagine youre doing this because you find it an interesting project or the existing systems dont meet your needs.

First, do you know what sort of speed controllers you will be using? Some have failsafes built in, and different types have different input signals. Most types need an interface to connect to a 40MHz remote control system - and this interface may have a built in failsafe.

[big_nipper]

Failsafes are simple devices and standard ones are available from model shops. These type just plug in between your Rx and speed controller/servo. Some speed controllers such as Vantecs and Robotechs have them built in so you dont need them on the drive. If you use a seperate Rx channel for your weapon then you may need one, but Rx relays such as the Electrolise (have a look at http://www.technobots.co.ukhttp://www.technobots.co.uk). If you are skilled at electronics then building one of these which simply switch a relay on with an Rx channel would be where to start. I built one with a MOSFET in place of the relay although I dont use it on any of our robots.

I use PIC chips for the bulk of my stuff.

I would be glad to help but I suggest you get yourself to a live event before you purchase anything and have a talk with roboteers. Thats the best way to learn and aviod making the same mistakes as we all have done while building.

Tip for the forum: Dont visit the Power Light thread Its enough to confuse anyone

[big_nipper]

Just looked at your website, and noticed you are planning on getting the Pro 120 speed controllers *at this point everyone else knows what Im thinking about saying* but just for your benifit I would be careful in your choice as Ive learnt the hard way. I sent 3 off to be fixed last month and we have 3 in our robot and have 4 spares just in case. Some people dont have any problems with them but whatever the reason we do. Having said that we are still using them.

Im assuming the interface/mixer you are talking about is the 4QD one. Is this the one that requires servos to move pots? If so Id aviod that one, there are much better ones out there. I built my own and this provides the failsafes.

[big_nipper]

On average one breaks every 2 meets. If we get say 8 fights in a meet then thats an average life of 4 hours per controller. It might just be our setup that causes it. Other people have gone years without troble. Its your choice as to what to get. They are cheap and if you can afford a better controller then it will be worth it.

Our first robot used 4 of them back at Series 5 and we simply reused them in the new design. One thing we did throw away was the 2 DCI-111(?) Mixer boards we had as they kept setting one of the speed controllers to full speed every now and then. Instead we used Derick Foxwells mixer boards until I made one. Still got 2 of them somewhere but I took the Opto-isolators off one to use on something else. We only used these twice at series 5 and have been in a drawer since.

If we knew what trouble we were going to have then we would have choosen something else, but its kind of hard for us to change now as the robot was built around them. What 4QD say is that they will last alot longer if we dont turn the acceleration/decel setting to minimum. Maybe we will try that one day and suffer with slower response.

[big_nipper]

Taken from Techobots web site.

4QD pro 120s £130 Each + 4QD mixer £42.53
Total: £302.53
RoboTech £395.95

What isnt clear is if you need failsafes for the 4QD mixer and this is the cheapest configuration that will work.

So for just an extra 23% cost you get the best out there so far. Its simple to wire up, only one box + Rx and has builtin failsafes and more functions than any other contoller out there. Oh and its lighter!

Your choice. If you want really cheap then you could even make your own (check out OSMC in google) but if it doesnt work first time it will probably end up costing more.