Gego - I've sent you a mail. Thanks for the reply.

Orraman - I experimented with onboard mixers but there are several problems that are better resolved by mixing in the Tx. One is drift - the zero point is critical with a boat where any propeller movement is bad (Think of the lacerated fingers if the props move while you're lifting it out of the water!). The admittedly small selection of mixers I tried showed drift resulting in propeller movement no matter how trimmed. Another is size - some of these boats are very small.

The 1/96th scale picket boat for instance is 6" long and uses only mixed props for steering - no possibility of a rudder actuator or micro servo in such a tiny hull. The Futaba 6EX 2.4 gHz Tx is so vast in comparison to the boat that the model could actually be transported inside the radio! Here's the picket boat leading the mother ship "Mars" into harbour:

I started to look into implementing a mixing functionality into my encoder software. It appears to come down to evaluate the existing two sticks and mix this information into three channels (rudder, right motor, and left motor). My biggest concern right now would be to run out of memory on my small microcontroller but this could be easily addressed by going to another micro within the same family. Other than that the existing components should be sufficient at the tx side.

Aveling,
I now have no access to enclosed water but I still have a Marblehead yacht fitted with Launch Link radio so I envy your situation.

For interest only.
I have hacked down Kevin Goom's mixer from Post # 59 to mix rudder to 2 shafts and fit the superseded Picaxe 08M chip which was already fitted to a Protoboard with a pot and 2 servo connectors.

I have not come across drift in digital mixers but these 2 lines in Kevin's program might well take care of that as well as any jittering.

if Temp<3 then '...Comment, add a bit of hysteresis
Temp=0

For the small boat I assume you are using 'tank' style steering somewhat similar to the above program, interesting.

Dave

heres some photos you might find interesting. discouraged by 9x oversize and menu overkill i went to a t6 which was about half as big and much easier to use. still smaller was this syma toy heli remote at about 1/5 the size. and it has pots unlike picoo and aero ace remotes. upgraded with ppm/power pigtail its compatible with frsky, esky fm, and flysky.

(lotta skies around here )

Simple Arduino example:

http://www.arduino.cc/cgi-bin/yabb2/...m=1193927390/0

Not interrupt driven, but if processor has nothing else to do then who cares. It works.

I recently started building www.pikoder.de to make my small yet versatile encoder which uses an 8pin PIC controller available - you only need two additional pots for a complete a two channel ppm encoder. Please check out www.pikoder.de/indexEN.htm for more details. I will add more information as time permitts.

Originally Posted by aveling

Thanks for the replies.

I'd discounted the NE5044 because I've not been able to find an affordable source of it apart from buying up old radios on ebay and pulling the chips. Is there a source, maybe under a different part number?

Thanks again, David

The original company that developed the 5044 was SIGNETICS , they did have a precursor to the NE5044 but I cannot recall the number , in any event it would be harder to find than the now obsolete 5044 .
Phillips had very little IC expertise back in the day and purchased Signetics in an effort to gain IC capabilities . Signetics had been started by a group of fellows who had worked for Fairchild Semiconductor , a Silicon Valley, California semiconductor pioneer .
By now of course , the 5044 has become passe as there are a multitude of chips that can do everything it did and more .

are you guys aware there is an encoder chip available that only costs a buck or so and has features no diy or commercial chip could ever hope to compete with?

http://www.rcgroups.com/forums/showthread.php?t=1631369

for example below shows a couple ive soldered to breakout boards. the m64 one is being used in a cheapo simulator case and the m128 in a 4ch micro heli radio. they are actually interchangeable.