Here is one, and another one is below that one. It is a pressure sensor whose output is converted to a digital form. These boxes all seem to use the same 1970s design which uses a then-popular digital voltmeter chip to do the A-D conversion, and then they use an EPROM lookup table to convert the straight binary into gray code binary. The connection to avionics is historically using gray code (see e.g. here) which is 10 or 11 wires, or using ARINC429 which is a serial connection (2 wires, shielded) but very few things support that.
I think all the normal GA-market altitude encoders are same or similar. @wigglyamp will know.
alioth wrote:
In quite a lot of instances, these type of aircraft don’t have electrical systems or ancient electrical systems powered by a dynamo. I don’t know when this photo was taken or in what country, but it’s only a recently that portable EC devices have been available and they are only approved at the moment in the UK.
Photograph was taken 3rd January 2018, in Spain…..
The mix of helicopters and fixed wing in the same circuit is very bad. A couple of years ago we had a local helicopter, in initial climb after take-off swap paint with a twin Partenavia also on initial climb. This is about as close as you can get without being hurt. Only the paint to show the contact, no other damage. Rotor against elevator.
Is that do do with mixing the types, or with having two circuits very close together?
Or, to put it another way, had the helicopter lined up on the runway and taken off, would the collision have happened?
Steve6443 wrote:
Photograph was taken 3rd January 2018, in Spain…..
Please tell me the pilot wasn’t Scottish (a pilot who occasionally visits my home airfield is a Scot usually based in Spain and owns a Bucker).
Update: a bit of Google searching shows it was him (Don Milne) :-( I only flew with him a couple of times (he flew with me in the Auster, and also he took me flying in one of his helicopters) and didn’t know him that well but it always hits you when it’s someone you knew.
Although I didn’t know Don all that well, judging by the helicopter I flew with him in, he wasn’t the “anti transponder” type. Of course I don’t know what he had in the Bucker.
Very sad to hear of your friend, Alioth.
Timothy,
The helicopter was using the grass, the Partenavia the runway. The CAA then decided that both Heli and Fixed Wing must use the same circuit and altitude, even worse than before; last November this was changed again with the helis having the circuit on the opposite side now.
The ascent of FLARM in the gliding community shows that lack of an electrical system is no obstacle.
The Mode S Trig we have has an in-built encoder, and just needed a T-piece in the static air feed to link with a tube from the aquarium section of the local pet shop.
Timothy wrote:
Really, I didn’t know that. Sorry for the thread drift, but how does an encoder inform the transponder of the altitude then – is it digital? Has it always been digital? I assumed that in the early days of Mode C it would have been a simple voltage.It has always been digital. The old style is 10 or 11 parallell wires, the new style is serial transmission.
And are all encoders cross compatible, or do you need the right one for your transponder?AFAIU they are all compatible as long as they both accept either serial or parallell input.
