Re: receiver question 1b: interference [TANKS]

[<adt22-at-drexel.edu>]

Thanks, have a great vacation!

----- Original Message -----
From: Frank Pittelli <frank-at-rctankcombat.com>
Date: Friday, June 23, 2006 11:17 am
Subject: Re: receiver question 1b: interference [TANKS]

> Amir Tahvildaran wrote:
> > Hmph, I think I installed the relay diode correctly with your 
> > description and this site's diagrams:
> > http://www.kpsec.freeuk.com/images/diopro.gif
> > http://www.kpsec.freeuk.com/components/diode.htm
> > 
> > here is the problem relay with the diode installed, white is + 
> relay 
> > coil, black is - relay coil:
> > http://www.cs.drexel.edu/~adt22/tank/relay_diode.jpg
> > does that look right?  I didn't test it reversed because I was 
> pretty 
> > sure that (a) it was right (b) it would blow something up if it 
> was wrong.
> 
> The diode placement is correct.
> 
> > Anyway, when I activate this trigger relay I still get activity 
> on the 
> > rotate.  What is *really* bizarre is that when I touch the bare 
> black 
> > wire (relay coil), it activates the rotate!  I know that the body 
> has 
> > some electrical property, like high capacitance or something - 
> but I 
> > still don't understand whats going on...
> > 
> > Here are two overall shots of this messy circuit:
> > http://www.cs.drexel.edu/~adt22/tank/overall_turret_circuit.jpg
> > http://www.cs.drexel.edu/~adt22/tank/overall_turret_circuit2.jpg
> 
> Based on this description, it's probably a wiring problem, not an 
> RF 
> noise problem.  Unfortunately, I'm about to leave for the airport, 
> so I 
> can't continue this thread in detail.  But, if you can activate the 
> rotate simply by touching the bare ground wire, then I would 
> suspect 
> that the transitor shown in the picture has something to do with 
> it. 
> That is, it is seeing a little current on it's control side, which 
> is 
> allowing a large current on the load side.  What is that FET for?
> 
> I would proceed as follows:
> 
> 1) Disconnect the rotate and trigger circuits from the common bus 
> and 
> test each one individually to make sure you have the proper wiring.
> 
> 2) Use separate batteries for the control and load side of each 
> circuit, 
>  with completely separate grounds.  In general, this is a good 
> thing to 
> prevent voltage and current spikes on the load side from finding 
> their 
> way onto the control side.  It also prevents electrical noise on 
> the 
> load side from interferring with the control circuits and 
> eliminates the 
> possibility of having the control side completing a circuit 
> involving 
> the load.
> 
>       Frank P.
>