burning question - HSI?

[ruprecht]

Ok, Lets move the optical sensors to the opposite corner because the rotary encoders need to go where you have them now.

I kept the rotary encoders in mind when I positioned them, I thought the 7-segs needed more room than the encoders. I think there's enough room, it will depend on the dimensions of the encoders.

add the encoders and the 7 seg displays in the corners.

Next on the list

Can we get a detail shot of how you have the inner servo connected at this point?

Nothing connecting it at the moment, all in my head.

[ruprecht]

optos can be moved up to straddle the gears

If necessary that can be done. I'm concerned about separating the ring gears too far as it extends the length of the bug and RMI indicators which will give us grief in the end if they start to droop. Let's see if there's enough room as is, then revisit.

3mm is a nice thickness to work with but I've made gears successfully from thinner stuff.

Coincidentally, I have worked using 3mm gears right from the start

One more practical consideration, we'll be home building these, so try not to make the tolerances/clearances too tight. That makes them really hard to build.

Trying, but there is a limit to how hamfisted we'll be able to be This is quite a precision instrument! We could always scale up to a 4" model to give us more wiggle room, but that affects gearing and all sorts of things.

it's hard to go past the little brass tubes that you get in the hobby stores

picked up a selection of these yesterday at Mr Toys

I myself would prefer the BK style, but hopefully we'll be able to mod your mechanicals to suit the different style.

I think the hard part is in the mechanicals, the look of it can probably be easily modified to suit almost any model once we've got the basics down. I'm working on the F-16 HSI a) because it's what I know, and b) because I know there is a big community of people over at ViperPits just screaming for it!

[AndyT]

In milimeters to 3 decimal places? I'm going to have to find my calipers...

Here is an encoder.
http://www3.alps.com/WebObjects/cata...1E15244B2.html

[ruprecht]

We may not always achieve accuracy, but when we stop trying we guarantee it won't be accurate

[Michael Carter]

I sort of though this was going to be a 4" unit.

You'd have a lot more space to work with.

[ruprecht]

Here is an encoder.

Cheers mate - BSAI uses the Bourns 3315Y-1-006 - dimensions for that one would be awesome too.

[ruprecht]

first snag:



The rotary encoders work really well, but the 0.3" 7-segment displays are too big and occlude the compass ring. This is based on the DigiKey 67-1416-ND single digit module. Couple of options:

- Find a smaller commonly available 7-seg module, probably 0.2" or smaller, and preferably in a 3-digit block. Best option. There is a candidate here but they are $21.30 each!
- Redesign to 4" to make enough space. Not my favourite option due to the redesign work required.
- Dispense with the 7-segs altogether. Will piss off the F-16 community and leave you only analog displays of CRS and HDG BUG information. Workable option.

Whaddya think?

*EDIT*

OK I tried it with the Kingbright KCSA02-127 0.2" SMT single - and it JUST fits if I relocate the top mounting hardware. There's about 2mm or clearance to the opto flags with the relocated hardware, so it's all good.



So here's a challenge guys - find these or similar 0.2" 7 segs at a reasonable price for 6!

[AndyT]

Ask and you shall receive:

http://www.bourns.com/pdfs/3315.pdf

Can I have a 3/4 side view of that last shot?

Ok, Try this:
Since the LEDs are SMDs (Surface Mount Devices for you non-electronics types reading this) we can put them on the face of the front plate and cut holes for them in the final faceplate. They fit and if the faceplate is 3mm thick, they will be flush with it. AND they will not be interferring with the rings behind them at all.

[ruprecht]

Another update, I'll explain later:



*EDIT* OK I've dispensed with the optointerrupters and the flags, they're just too big. It was suggested above that magnetic reed switches or the like would be better, I think that's a great idea. Any suggested items, with dimensions and/or datasheets would be awesome.

I've added another large gear for the CDI assembly, and shown how it fits together. I decided to do it this way as it's more rigid and precise then the folded-metal approach, but it is heavier. There will be a brush contact shaft running through the middle of the gear which also mounts it on a 608 skate bearing or similar, again to aid rigidity and ensure it rotates precisely in the centre of the assembly. The CDI servo control board will be mounted on the rear of the CDI gear. There's about 20mm of space between the gear and the plate behind it for the board.

PS dimensions on commonly available steppers would be sensational.

[AndyT]

We can get the LEDs from mouser for $2 each which is about as cheap as we are going to find them I think.

I understand the 4th ring is the mount frame for the CDI Arrow plate. Nice. It will fit right thru the center of the others and is strong enough not to bounce around because it's ultimately held by the same mount gears. I might make it 5 or 6 mm in thickness though because it has to bear the weight of the servo along with all the rest of the hardware.

WOW! Steppers are costly. I'm looking...