"UN COMMANDED" START WITH REMOTE BUTTON FOR DL1

[jcmagne]

I read, in a previous post (july 2007), someone said that it was possible to use a shortcut for the remote button whith a 1K ohm resistor between 5v and start/stop input in order to provide, if i understood, about 5 mA current , to prevent autostart by uncommanded grounding.
Is it dangerous for DL1?
does it work fine?
jcmagne

[RTUSA]

Sounds both reasonable and safe.

[jcmagne]

Despite all what we try, when engine start, remote button start DL1 itself ...but ,very strange, never stop it itself.
We have no more idea ....may be a wood stick to push the button of DL1...do you really think that remote button sold by RT, would resolve the trouble? and why?
desperate user...
JC

[RTUSA]

JC:

Maybe the best thing is to use the autostart function (as opposed to a stick) and forget the remote start button and remove it completely, as there must be some kind of interference in your application coming in over that line.

Auto start based on speed works very well in many applications, you can autostop based on speed - or simply push the button before removing the card. I personally (when racing) use autostart based on speed (50 kph) and manually stop the logging.

Would this work for you?

[tristancliffe]

jcmagne - sorry for not replying to your email over the Christmas break.

We use a remote start/stop button with a 1kOhm resistor pulling it down to earth, as described. It works a treat for us. We use an old computer network cable for the shielding too, which might be some help.

I ALSO use autostart (but not autostop, as I can't think of anything that would work for us, because I don't want it stopping when I spin, and our DL1 is powered by the ignition, and turning off the engine cuts the power, so I can't monitor engine revs either... I have no idea how to use autostop without it stopping when I don't always want it to.

But I try to use a manual start, and have the autostart as a backup in case I forget, which massively reduces the chances of a run not being logged.

The 1kOhm resistor has worked well for us, and eliminated all the problems we had with random start/stops whilst driving. I recommend it to anyone.

[jcmagne]

Tristan:
the resistor is between the earth and the button?
the first thing we try was a 1K resistor between start/stop pin of DL1 and remote cable and unfortunetly it don't work for us.
I think i am going to use autostart as said Al and an unused analogic input for autostop with +5 V throug the button and 5V reference.
Thanks for your help.
JC

[tristancliffe]

A snippet from an email from RaceTech...

Hi Tristan,
If interference is being picked up on the external trigger line, you could try adding an external resistor to increase the strength of the pull-up on the external start/stop input. Connecting a 1k resistor between the input and the 5v reference should do this.

Regards,

Martin

The remote button is a switched earth, i.e. the wires go from earth, through the button, and to the remote input terminal. The resistor goes between 5V Reference output terminal and the remote start terminal.

Hope this helps (and if I'm wrong I hope I'm corrected as I've done it from memory).

[RTUSA]

Tristan:

You are correct. The remote start switch circuit still attaches directly to the DL1 - the resistor is not inline with the switch, it goes directly between the trigger input and 5V. Obviously needs to be fairly high resistance ie 1k ohm.

I assume this worked for you?

[tristancliffe]

Like a dream - not had a problem since.

The only 'issue' I have these days is starting logging before I have a GPS fix, so I have to trim the wibbly bit at the start.

[jcmagne]

Tristan's car has a carbon body, us, our single seater is older (1980) with an aluminium body.
is there more interference with aluminium?
JC

[tristancliffe]

True, but the wires run mostly along the floor (which is aluminium), round the engine (iron/steel/aluminium), behind the dash (lots of wires), and is near the battery, datalogger and ECU.

I doubt it would make much difference having an earthed aluminium body. Try it - you won't damage the DL1, and if it doesn't work I'm sure we can come up with an alternative solution.

[jcmagne]

It doesn't work for me...
still uncommanded start...
I thing I am going to use autosart (speed) and stop with the button by +5V on an unused analogic input with autostop config on variable > 3V ...
JC
last solution would be to buy a Reynard 883...but not possible for F3classic...

[tristancliffe]

What button are you using?
Does the uncommanded start only happen when the engine is running, when just the ignition is on, or just with the datalogger on?
Does it do uncommanded stops as well?

Lol at the last sentence

[jcmagne]

the uncommanded start of DL1 happens only when engine is running, a few seconds after starting.
And very strange, we have never uncommanded stop!! even the engine is running for a long time...
Really, I don't understand why...
JC
button comes from a Mirage F1...(old jet fighter made by Dassault)...
very nice button... over all suspicion...(tested by myself!!)

[tristancliffe]

That leads to a question for RaceTech:

Can any hysteresis on the start/stop input cause interference to START logging, but not STOP it, or does that fact it only ever starts logging randomly point to something else?