Gina

Been out to the observatory and playing with the motorised opening and closing of roof and window. The chain was tending to ride up on the outer cheek of the small pulley. Cured with a nail that limited the sideways movement of the chain. I can replace this with a 3D printed guide for a more free-running chain. The limit switch for the closed position will need to be quite accurate. There is very little between not closed enough and motor stalling. The open position is much less critical - it doesn't matter if the roof is a few millimetres short of fully open. It does matter if the roof is a few mm from fully closed as the weather strip will have a gap and not work. One possible solution to this is an extension spring on the end of the chain.

Before deciding on where the rain sensor will go I need to check that the rain here is sufficiently polluted to trigger the rain sensor - I expect it is.

I shall put the control box on the wall in the warm room. That will keep it free from the dew that often descends in the scope room. The RPi will probably go in a separate box high up in the warm room to get the best WiFi signal. The optocouplers can go on an RPi HAT together with a buck converter to provide the 5v supply for the RPi. That will keep all RPi stuff separate from the Arduino.

Thank you Julian, I will take it easy.

I'm definitely feeling better today and hoping to do some more on my observatory.

Feeling better this morning so hoping I can co a bit more to this project today.

How was it last night Dave?

Thanks Dave.

Good luck Dave - I'm off to bed now.

This screenshot shows the connections of the dual motor driver when not used as an Arduino Shield. I only have one motor so will be using the top half only. M1EN/DIAG and M1PWM will be connected to +5v. Arduino outputs will connect to M1INA and M1INB to control motor power and direction. M1CS will go to an analog input to sense motor current. Here is a diagram of the Arduino Nano pin connections. Analog pins except for A6 and A7 can be used as digital, adding up to 6 extra digital I/O lines on top of the 12 standard digital pins.

Just had a look outside, at the sky. Probably dark enough for NB imaging, a few stars showing and the odd planet or two but there's also cloud. CO shows this as the best that can be expected with more cloud in the next hours. No, I wasn't thinking of doing any imaging, just thought I'd have a look at the sky before I go to bed. I only ventured just outside the door.

Yep - still lots to do and only 5 months left this year to do it in! BUT I want it ready long before the end of the year.

The chain is now attached to the blocks on the ROR framework and both roof and window now open and close from the motor drive though ATM the window needs pushing open at first before its weight takes over. There is still the motor control unit to design and build.

Left to do on this project :- Sort out limit switches Position rain sensor Design circuit board layout for the electronics Design and print case for the electronics and local control push buttons Build electronics unit Sort out how to start the window opening when it's upright and balanced closed

I probably won't be doing any imaging for several weeks at least. There isn't really enough dark time to make it worth staying up for, at least not until I'm 100% fit. I shall just slowly work on my ROR chain and motor drive during the daytime.

Arduino analog input :- 0-1023 corresponds to 0-5v so 1A = 140mv = 1023x140/5000 = 28 and 4A = 112.

Test completed and that will probably all I do today regarding physical effort. Opening roof/window between 1.2A and 2A, closing up to around 3A. Fully open or closed stall current 4.8A. Motor drive with chain and pulleys etc. produced a certain of grumbling and groaning but operated fine. I think the chain may want lubricating - some of it is quite rusty. Motor current ranges and conclusions :- > 1A - OFF or clutch disengaged 1-4A - Normal operation > 4A - motor stalled - roof fully open or closed or obstructed.

I won't! It's only my medium sized bench PSU at just 30v 5A jobby and not heavy - 4-5Kg.

That galvanised clothes line pulley wasn't good enough - the cord rode up over one of the cheeks. Replaced with a 3D printed one which works fine.

Next will be to check the motor again with bench PSU and measure the current.

Now the photos. Firstly, the new pulley block for the window control. And then the ROR chain drive.

Been out to the observatory and done a bit more. Connected the chain ends to the brackets on the ROR framework using the 40mm diameter SS penny washers.

Thank you very much, Tom. I have had tests and awaiting the results when I see my doctor in a few day's time but I think if it was anything serious the surgery would have got back to me.

Thanks for that Wim, when I get round to my weather station that could be very useful.

I was still light when I went to bed (just) and a lot of the clouds had gone but with dark cloud on the horizon to the south and west anything could happen.