Originally Posted by RVadmirer
I would love one of these to go with my pitch trim.
I have looked into it. They work "kind-of-sort-a. As an altitude hold its no where near a rock solid like what we now have available with the TruTrak or Trio EZ1. It only moves the trim. The true altitude holds have a dedicated pitch servo that moves the elevator.
If you are a hobby electronic guy you can build one. Even if you are learning electronics, its not impossible but its not simple either. You pretty much are on your own if you can't get it to work.
There was a used one on eBay a few weeks ago. I was going to bid on it for fun, but the bid got to hundred and half, which more than what the raw materials would cost to make one. The main thing to get is the PCB.
These guys in Europe offer PCB and parts kits and pre-built units ($410 euro) $554.
Be aware there have been improvements; known errors in the original design have been corrected. The big thing is getting a PCB (etched circuit board). The other parts are very standard. The europe guys sell just the PCB for $70 euro, but you could have one made locally for less. Ideally you would have a batch made to get cost down.
The EZ trim is not a set and forget altitude hold.
I would not say its a waste of your time, but I would say its more for fun, for learning how to make a little microprocessor controlled device and make it work as best as you can in a RV. Don't count on it to being a rock solid altitude hold.
Personally I have flow RV's long cross country coast to coast with out any autopilot and don't find it hard. Usually my knees do a pretty good job of pointing it. With a wing leveler and trimmed in smooth air the X-C work load is even lower.
If you want true altitude hold get a commercial units ($1,800). People are very happy with their commercial altitude holds. I never heard of one being removed, but I have heard people that took their EZ trims out. Check out the canard Forums. Those guys are more likely to know about the EZ trim.