Electronics

Failsafes monitor the quality of radio signal going to your speed controller from the receiver so if it receives an in-valid signal, interference or no signal at all it will prevent that from reaching the speed controller and making you lose full control of the robot.

When it does sence no signal or receives an invalid signal the failsafe detects this and sends its own signal to set the controller to neutral so your robot should stop dead.

There are mainly two types of failsafes...

Built In Failsafes : These are built into the electronics of the speed controller so its all there ready for you to use.

Plug In Failsafes : Are extra little units that plug in between your receiver and speed controller, and they do the exact same job as the built in ones.

If you tell us what make of speed controller you are using we would be able to tell you if it has a built in failsafe or not, or you can probably find out by reading the documentation that came with the speed controller.

Chris - http://www.featherweights.org/forumBreak

Your LED will also need a resistor. You may have an LED with a built in resistor - if your LED is rated to 12V or 24V then it probably has a built in resistor. If youre using a plain LED from Maplin or wherever then youll need an extra resistor in series with it. The value of it will depend on the voltage youre running at and the forward voltage drop of the LED.

My failsafes are part of the receiver not the speedos. When signal is lost, they shut everything down.

Ive got a 12v Maplin LED.

Maplin do various types, if you have one from this page http://www.maplin.co.uk/search.aspx?MenuNo=330&MenuName=5mm%2B12V%2BStanda rd%2BLEDs&worldid=3&FromMenu=y&doy=9m7http://www.maplin.co.uk/search.aspx?...andard+LEDs&wo rldid=3&FromMenu=y&doy=9m7 then your fine, the others require resistors. Its easier just to get one of these in my opinion, save yourself the hassle.

Ok Sorry to Hijack this thrend but rather than start a new one.

I want to build Ian Watts Failsafe system as can be found here:
http://www.teambigbro.co.uk/failsafe.htmlhttp://www.teambigbro.co.uk/failsafe.html

What i need to know is, is it possible to make this whole board run on 5v by changing the relay from a 12v coil to a 5v coil. I have looked at the data sheets for the Flip-Flop, The 555 Timer, the FET and the Transistor and all appear to work down to 5 volts.

So can anyone verify this?

Thanks
Regards
Ian.

Should be fine... You may need to substitute the FET for a transistor on the output if it doesnt work.

Please note you will get a better response if you start your own thread in the future.

(Message edited by Kane on December 08, 2005)

I dont see anything that wouldnt work at 5V but I would double check the timing doesnt alter otherwise it wont work as expected. Also it will be very sensitive so make sure you have a good Rx signal. The ones Ive used in PICs filters the Rx signal such that one off errors will not trigger the failsafe and infact it needs 10% pulse errors within any 2.5 seconds period before it will failsafe. Even this has false triggers in our robots every now and then for the robots that dont use PCM.

Just spotted on the site that Ian says:
Specifications

The maximum input Voltage is limited by the 555 chip to 15 Volts

The minimum input voltage is 5 Volts