Chris1 has alerted me to this thread, so as the designer of the mixer in question I'll try and clarify the situation as best as I can.
Firstly, to be pedantic, my mixer doesn't do *precisely* what Chris specifies. In "dynamic" mode the mixing isn't disabled immediately upon leaving (throttle) neutral, but instead tapers off linearly from 100% as the speed increases finally reaching 0% at some user set speed. The range of setting (by potentiometer) of this cut off point is continuously adjustable from 30% of full speed to 100% of full speed. Also rudder control is retained in neutral, as I find this significantly improves the turning action on my tug though I've been given to understand that in real life a twin motored boat when stationary is manoeuvred on differential throttle control alone. However, the *spirit* of what Chris wants to achieve is addressed by my mixer and I see he recognises this in a later post.
But the whole point of my offering this unit on a trial basis prior to it becoming commercially available (from Technobots) is to tweak the design to what people *need* rather than just offer what works well for me. My beamy tug isn't a high speed Najade and neither is it a long thin battleship with scale sized rudders that don't work very well. So if the majority of trial users find they need more or less adjustment of a particular feature and it doesn't compromise the remaining users, then consider it done! As I say in my 6 page PDF file on the SRCMBC website, any software mods resulting from the trial will be offered as a free upgrade (by chip swapping) to participants of the trial so there is no risk in being a guinea pig.
A better solution to meet Chris's *exact* requirement (and here I shoot myself in the foot) would be for him to use my mixer in "static" mixing mode, set the mixer gain to his desired 10% (in static mode it's continuously variable from zero to 100%) and connect the rudder channel of the mixer to a spare channel of his receiver. Then use that spare channel only when at zero throttle in much the same was as you would use a bow thruster - even the rudder doesn't move as he specifies!
This of course requires that you sacrifice a spare channel that you may prefer to keep for controlling other features whereas my "dynamic" mixing was developed to have the best of both worlds, keeping rudder control simple and seamless from zero to full speed.
So how effective is this "dynamic" mixing? Well, at the Alfold show last year I demonstrated a prototype of this unit and after trying my tug in "dynamic" mixing mode on the water for himself a member of Swiss Cottage MBC was sufficiently impressed to buy 5 units to equip his fleet. After installing the first unit in his Drumbeat of Devon he took it to show his club members and they promptly ordered a further 8 units! Since the (enhanced) trial unit was announced they've taken 4 more.
I plan to be at Alfold again this year, plus Beale Park so any of you are similarly free to try it out for yourselves. Other show suggestions in the southern area are welcomed for consideration.
As explained above the mixer is not yet available from Technobots and is not to be confused with what was described as my "kit" for a very basic DIY V-Tail mixer that has been on Technobots site since 2010 or thereabouts - well spotted dem555. In fact the old unit not a kit but just a programmed microcontroller chip and the rest is up to you (parts list and build instructions on their website) - whereas today's offering is a ready built and tested production quality PCB (see attached photo and note the Technobots branding) and only differs from the final release in that you need to make your own access holes in the supplied box and you don't get a pretty label or a printed instruction leaflet - instead you download the aforementioned PDF file from the SRCMBC website.
I still have some of the 20 trial units left for which I'm asking £30, inclusive of 1st class signed for postage in the UK. Quite what Technobots will be asking for them later on I don't know.
I'll keep an eye on this thread from now on and contribute as necessary.