ADF - occassional leveller start up glitch

[Slats]

Hi kevin,

I am loving the ADF unit and underway it has been working fine. I have about 4 hour use logged on it all up. A couple of hours running and and another couple hours with it involved with setting up a boat on the bench.

I have been doing a lot of on the bench testing over the last few days, setting up the ballast servo on a SD I am assembling. This process logically has seen me turning the Radio, then boat on/off for short periods.

What I have noticed is that occassionally (say 1 on/ off cycle in say 10), the leveller servo on turning the boat on after the radio goes to an extreme position. When it happens the servo only ever goes to an extreme position on one side. Given that I tend to overdrive the rear planes, the boat setup that this leveller is rigged for, just has the rear planes hanging off a 5v rail from the RX, that is, the leveller is totally automatic, not linked to any TX input by me.

I noticed that turning the boat off / then radio, and then turning radio and boat back on the problem seems to resolve itself.

Any ideas what might be causing this. Fortnuately it seems like it only ever happens on start up and can be corrected by shutdown / restart, but would like nonetheless to know if the unit needs servicing or if this could be the start of a bigger problem.

Many thanks
John

[KevinMc]

Hi John,

That's certainly a new one on me. In all the years I've been using my ADFs I've never once seen, or even heard of, that kind of behaviour. Having said that, I've always got both my inputs connected to live channels on the Rx so it's very difficult for me to say if you're experiencing some kind of unique problem because of your setup, or if it's a pre-cursor to worse things on the horizon.

One thing I can reccomend as a test would be for you to hard tie the pitch input channel (white wire) to it's ground (black wire). Although the ADF is designed to operate with unconnected inputs, as you are doing, it's possible that something's not being pulled strongly enough. You mentioned powering the ADF from a 5V rail - is this in addition to having the failsafe channel plugged in, or are you not using that? The reason I ask is so far as power is concerned both functions of the ADF will pull their power from either lead, so you can plug in only the failsafe channel but still have both the failsafe and pitch outputs fully functional. (I bring this up because even if you're not using the failsafe channel, you may find it easier to power the ADF through the failsafe input while shorting the pitch input to ground, still driving the stern planes from no input...)

I'm glad to hear that everything's working well for you except for this one glitch. Please let me know if shorting the input has any effect.

KMc

[Slats]

Hi Kevin,
Yes I am using the FS too.

can you please explain what "hard tie the pitch input channel (white wire) to it's ground (black wire)", means?

BTW the input voltage comes from a separate BEC of the step variety. It has 7.2v entering it and 5v leaving it for the Rx.
And yes in addition I have the pitch side of the ADF input connected to a Y harness that goes from the BEC to the Rx. So what your saying is as the FS is in use the whole ADF including the pitch side already is getting voltage from the RX via the FS plugged in? If so should I try just leaving the ADF input not connected to anything?



Thanks
J

[KevinMc]

Hi John,

That's exactly correct - For the setup you have as long as you've got the FS input plugged in you do not also need to have the pitch input connected to make use of the pitch output. You only need to connect the ADF's FS input to the Rx and it will draw power for both the failsafe and pitch circuits. (I thought it would make it easier to set it up that way.)

As for the "hard tie", use a piece of jumper wire to create a short circuit between the white (signal) line on the pitch input lead to the black wire (ground) on the same lead. If you've got any small value (< 1K ohm) 1/4W resistors floating around your shop you could also bridge the connection with that. The ADF's inputs are pulled high internally through a very weak pull-up circuit, but it's possible that the pull-up isn't strong enough to gurantee it's in a defined state - that could be confusing the ADF's processor. (Admittedly I'm grasping at straws here, but it's worth a try.) Just be sure you don't accidentally connect the red lead to the black lead on the ADF - that would be bad. (Try to imagine all life as you know it stopping instantaneously, and every molecule of "smoke" instantly exiting the ADF...:pop)

KMc

[Slats]

Given the scary nature of a positive / negative short circuit - to be avoided (understood), How do you get the hard tie between white signal and balck negative to stay put?

And for electronics neanderthols like me who deal with bigger neanderthols at the component store what are some units I can ask for less than 1K ohm? If I go in and say can I get a 1/4 watt resistor less than 1 ohm - the customer service will be robotic and ask what value?

As for the ADF's confusion - and this from an electronics neanderthol, but could it be that as I have the pitch input also getting 5v and the signal wire doing nothing, could this be getting confused with the FS getting the voltage too?


Thanks
J

[Subculture]

Is there a delay built into the software of the ADF, say for a second or so, when first switched on to allow the supply to settle down?

Also does the ADF use it's own linear regulator and caps?

[KevinMc]

Hi Andy,

Yes, there is a delay built in. I've found that some receivers take a while to boot up before they actually put any signals out so on power up the ADF will allow time for this. Everything on the ADF is adequately decoupled, although not all of the circuits on the ADF rely on a local regulator. (This is part of the reason the ADF is not recommended for use with 6V Rx busses.)

For anyone else looking in I've been emailing to-and-fro with Slats to get him the info he needs. Time will tell if the extra resistor cures his ails.

[Slats]

Hi all, e-mailed Kevin a few days back. It seems that the situation is directly linked to me having a power link going to the leveller, where I had the leveller working only as an autonomous device.
So in fact have not yet tried the resistor as it seems to have fixed itself through me removing the superflous power supply.

Thanks Kevin.
J