Gyro Switch

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=82 BGCOLOR="#006699" TEXT="#080000"> <div> <FONT SIZE="5" COLOR="#FFFFFF" FACE="Arial" ><B>JBVM Delemarre</B></FONT><B>     |     </B><A HREF="index.htm" TARGET="_top" TITLE="JBVM Delemarre"><U><B>home</B></U></A></div> <div> <B>Gyro Switch</B>   |   <A HREF="id73.htm" TARGET="_top" TITLE="Gyro Switch components list, circuit, PC"><U>Gyro Switch components list, circuit, PCB, component placement and cable connections</U></A>   |   <A HREF="id74.htm" TARGET="_top" TITLE="Pictures of the gyro switch"><U>Pictures of the gyro switch</U></A></div> <div> </div> </td> </tr><tr> <td valign="top" width=210 BGCOLOR="#FFCC66" TEXT="#080000"> <div> The article as published in the february 2001 issue of <A HREF="http://www.modelflying.co.uk" TARGET="_top" TITLE="http://www.modelflying.co.uk"><U>RCM&E</U></A></div> <bR> <div> <IMG SRC="194aae90.jpg" border=0 width="170" height="233" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <div> It is very rewarding to see one's work published!</div> <bR> <div> <A HREF="id73.htm" TARGET="_top" TITLE="Gyro Switch components list, circuit, PC"><U>Components list, circuit, PCB, component placement and cable connections</U></A></div> <bR> <div> <A HREF="id74.htm" TARGET="_top" TITLE="Pictures of the gyro switch"><U>Two pictures of the device</U></A></div> <bR> <div> <A HREF="id65.htm" TARGET="_top" TITLE="Downloadable files"><U>Download the PCB file</U></A></div> <bR> <div> <A HREF="id49.htm" TARGET="_top" TITLE="This is the English part of my home page"><U>Home</U></A></div> </td> <td valign="top" height=398 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> <I><B>Gyro Switch</B></I></div> <div> A gyro on-off switching device</div> <bR> <div> B<FONT SIZE="3" COLOR="#000000" FACE="Arial" >eing only an average weekend flyer I experienced a persisting problem getting my old and trusted Goldberg Anniversary Piper Cub airborne in a decent manner; it tended to wander from side to side on the runway before take-off. This was entirely due to my piloting skills because a friend can put it in the air after a very long, straight scale-like run-out. The answer to my problem came when an article in a German model magazine discussed the same issue, the solution being to introduce a gyro on the rudder channel. I rushed out and bought a mini gyro made by Ikarus in Germany and put this between the receiver and the rudder servo. The previous unsteerable Cub went of like it was on rails! Most fellow club members are unaware of this addition and believe that have mastered the art of a straight take-off.....if only!</FONT></div> <div> When airborne the gyro should be switched off because it tends to counteract on aileron induced turns whereby the tail of the model gets pushed down by the opposite rudder deflection. Due to the nature of the gyro (and the rather low price!) there was no extra input available to switch it off by using another Rx channel. So I designed small circuit that would just do that. Use an extra channel to switch the rudder out of gyro control while keeping it under full Tx command. The same circuit can be used to switch other devices on and off-line to the servo, such as auto-pilots etc. It is a simple and straightforward design using only eight components, three of which are integrated circuits that can be bought at any electronics component shop. </div> <bR> <div> <B>Techno babble</B></div> <div> How does it function? The incoming pulse from the extra Rx channel that switches the device on and off is used to determine the state of two outputs of a multivibrator, either on or off; if one is on the other is off and vice versa.</div> <div> The signal from the rudder channel is always put through the gyro and the output signal from the gyro, modified to counter act the movements of the plane, is put through a gate that is controlled by the output state of the multivibrator. So, depending on the input pulse length of the extra channel the gyro signal is present on a gate output .</div> <div> The rudder signal from the Rx is also put through a gate without being modified by the gyro and this gate is controlled by the other output of the multivibrator. Only one gate can put the signal through at any given time (depending on the output of the multivibrator) and thus control of the device depends on the signal of the extra channel.</div> <div> The output of both gates is fed into an 'OR'-gate. The nature of the output of this gate is such that it will follow the incomming signal of any of its inputs. After this a pulse inverting and shaping circuit follows and then the signal is fed to the servo.</div> <bR> <div> <B>Straight and narow</B></div> <bR> <div> Using this little device I can take of in a straight line, switch the gyro out and fly under normal control. On landing the gyro is switched in again and a straight-in approach is rather easy.</div> <div> The printed circuit board is simple to make. When using PCB designs from magazines I make a copy on a Xerox copier that does not distort the image and use transparent overhead projection sheets to print the copy on. I usually make three copies and then put them one on the other to get a really black master. Then I make a print on the epoxy PCB, sourced from my electronics shop, and after developing and etching, a nice PCB is ready to be soldered. The project is so simple; it took me just two days from design to airborne trials. Component placement can be taken from the drawing and wiring can be adapted to suit the R/C system that you are using. In all there are five connectors - two from the Rx:(rudder and switch channels), two to (and from) the gyro and one to the rudder servo.</div> <div> If you have any questions regarding this device <A HREF="mailto:delemarre@ciscon.nl" TARGET="_top" TITLE="mailto:delemarre@ciscon.nl"><U>I can be reached by e-mail</U></A> </div> <bR> <div> <B>Download the PCB design!</B></div> <bR> <div> It is now possible to download the PCB design and print it on an inkjet printer or laser printer using the files provided on the <A HREF="id65.htm" TARGET="_top" TITLE="Downloadable files"><U>download page</U></A>! Look for the file "Switch.pcb" and read the page!</div> <bR> <bR> </td> </tr></table></body>