Gina

I have steel bearing balls that I used in my Marble Machine of about 12mm diameter. The current wind vane has a 5mm hole for an M5 bolt and I think I'll try the same with PLA bearings and bearing ball at the bottom with the bolt head resting on the ball and the ball resting on a flat plate (something hard preferably, or maybe PTFE). OTOH I think those balls are a bit big and they are not stainless. I think it may be worth buying some smaller stainless steel bearing balls - only a few quid. What size of bearing ball would you recommend please @Chriske

There are two sites I had in mind for the wind instruments but one I used in the past involves using a ladder to attach the mast to a shed. The second is on the SE corner of the sun lounge, on the south side of the bungalow, with the bottom of the mast on the ground. The disadvantage of the second site is that the wind will be partly obstructed by the bungalow from the north. OTOH wind from this direction is generally less and also less frequently in this quarter. Most storms come from the SW or SE. We are sheltered from the NW by rising ground and tall trees. Checked second position and it's out of sight of the imaging rig. Also, the mast height is about the same as the roof ridge on the bungalow.

I think I shall use something like that for the wind vane but I was hoping to have the anemometer underneath. That arrangement will only work for something on the top. I could have the units side by side rather that one above the other though as in my original design and like the ubiquitous Fine Offset WS.

I agree with that but it mustn't interfere with imaging - ie. be in the FoV available from the mount.

If I can get a reading with a Force 1 - light air, I shall be well satisfied. That's 1-3mph. Anything less is Calm anyway. I get that with nice new ball bearings. I'm thinking of reading wind speed in integer mph anyway. Accurate enough.

Do you mean a hole in a PLA part with a stainless steel bolt? We need very low friction. Could easily try it though.

Thanks Kev they look good.

I'm looking for anyone with experience of miniature low friction bearings? I am looking at bearings for the wind sensors for my weather station. Previously I have used miniature ball bearings but being in damp conditions (even though well shielded), these have corroded. Probably oil (which collects dust) could be washed out and replaced with dry PTFE lubricant but I would still need SS bearings and I can't find these in miniature sizes. I'm wondering about using PTFE tubing eg. Bowden tube 2mm ID and 4mm OD and either 2mm SS bolts or round rod. Any thoughts, please?

I'm wondering whether to put the 5m mast in a place where I can get at it relatively easily rather than where the wind would be clearest. ATM I have no weather station so almost anywhere would be better than nothing. I also need to consider that I'm not getting any younger.

One thing I've found in the past is problems with the miniature ball bearings with damp causing corrosion. I'm wondering about using PTFE and SS plain bearings.

One thing I've found with the reed switches is they have considerable hysteresis (distance between closing and opening). I might yet go back to optical sensing.

No, I don't have a laser printer.

16K isn't either but maybe 15K is near enough. OTOH some of the voltage values are very close!

But several of those resistors aren't preferred values. No problem if manufacturing the resistors but we amateurs have to use the resistors we can get.

Pretty much decided to go with the reed switches for a couple of reasons. I was going to use a cylindrical arrangement but magnet and reed switches need to be something like 8-10mm apart so I think the traditional radial arrangement is going to be better, may be easier to implement too. Makes it easier to adjust the distance between magnets and reed switches to get the right overlap in operation.

I have a MUX chip it's an ESP32! 🤣 I like the 1-wire circuit but replacing the 1-wire with ESP32 which does everything.

Nuts to that!! 🤣 Just a bit of fun anyway - may play again later. I'm sure the best option is the ESP32 and either 8 digital or 4 analog inputs and the 1-wire circuit.

I'm wondering if I can produce a resistor network with standard resistor values viz. 1, 2.2, 4.7, 10, 22, 47. Suppose we make inbetween values by adding another resistor in series, like this :- 1 1 + 0.22 1 + 0.47 = 1.47 2.2 + 0.47 = 2.67 2.2 +1 = 3.2 4.7 4.7 + 1 = 5.7 4.7 + 2.2 = 6.9 Then between those 8 values we have adjacent resistance values in parallel giving in ohms :- 1000 549.54 1000 + 220 = 1220 666.7 1000 +.470 = 1470 948 2200 + 047 = 2670 1456 2200 +1000 = 3200 1904 4700 2576 4700 + 1000 = 5700 3121 4700 + 2200 = 6900 873 Putting these in numerical gives 549 666.7 873 948 1000 1220 1456 1470 1904 2576 2670 3121 3200 4700 5700 6900 Some of these are quite close together. Maybe some primary values (8) could be adjusted to separate the secondary values (16) better. The resistance values would translate to voltage if the array were fed with a constant current but that would make the lower values very close together. Better would be to feed from a constant voltage through a resistor, then the lower switches would result in a higher current and tend to spread the lower values. All this is getting very complicated and probably not worth the trouble!

The reed switches have arrived and I've checked their operation. They're very sensitive one of my little 3mm cube magnets will operate one at 5 or 6mm.

Labelling the reed switches 1 to 8 from the bottom upwards... Assigning v to the voltage across each of the series resistors - 1/7th of 3.3v 1 - 0v 1&2 - 0.5v 2 - 1v 2&3 - 1.5v 3 - 2v 3&4 - 2.5v 4 - 3v 4&5 - 3.5v 5 - 4v 5&6 - 4.5v 6 - 5v 6&7 - 5.5v 7 - 6v 7&8 - 6.5v 8 - 7v Then we would have 16. 8&1 - 7/2 = 3.5v which is the same as 8. with 4&5. So no difference between positions 8 and 16. I though I'd cracked it but not so!!

Here is a resistor network using preferred values that gives a voltage proportional to angle in 16 steps. Except that it has a serious fault!! I think.

Yes, I have a circuit diagram for using 8 reed switches and a resistor network giving a single analogue signal to feed to the ESP or whatever. Trouble is the resistors are unusual values. OK, these could probably be produced by using preferred values is series or parallel but it's a lot of resistors whereas 8 wires from one side of the reed switches could go to the ESP with the other ends connected to Gnd - much simpler. OTOH the 1-wire circuit above with 4 analog signals could be fed to the ADC inputs of an ESP32 giving another (more complicated) possibility.

Here's a first revised block/circuit diagram.

I shall be using the ESP32 for the wind sensors then and may add the rain gauge and maybe light level sensor - photo-voltaic cell.

Just checked the observatory roof control thread and the requirements are 1 analog input, 6 digital inputs and 2 digital outputs. I think the NodeMCU Module ESP8266 ESP-12E could cope with this.