Mel, thanks. We want something which will hold it whenever someone takes their hand off the crank handle; if they let go it runs away as described above. The U bolt idea is good though for holding it; we use a rope at present which does something similar. But thank you.
Paul, that is a good idea. Our shutter is pretty heavy so it may need to be a chunky battery. How do you go about charging up that battery? We’d need someone to remember to connect it to the charging circuit unless we always parked the dome in azimuth in the same position and set up a positive and negative contacts at specific locations on the dome and the on the rim of the supporting wall. But an interesting idea.
James
The battery charges automatically from the solar panel. No human intervention required and there are no electrical contacts between the wall and the dome. All of the slit motor, battery and solar panel are attached to the rotating part of the dome so nothing moves relatively to anything else. The purpose of controlling them all through a small computer such as a Raspberry Pi, which is itself fixed in position relatively to the UPS and takes its power from it, is that WiFi works regardless of the position of the computer as it rotates with the dome.
As for the chunkiness of the battery, it only needs to be able to open and close the slit once or twice before it is recharged from the solar panel. The power drain of a Raspberry Pi is tiny and any reasonable UPS could keep it running for weeks if not days. For a reason which I hope is obvious, the panel should be on the south side of the dome when the latter is in its parked position. If the azimuth of the dome is also automated, as is the case with my dome, it can be parked automagically in the correct position. Assuming that the azimuth motor is fixed to the wall, powering and controlling it should be straightforward.
The size of the panel and the capacity of the UPS will need to be calculated from power of the motor used and for how long it needs power applying.
Of course, with all that in place the dome can be fully controlled over the interweb thingy given an connection to the TCS, which is the rationale behind my plans. It’s all I need to make my observatory fully automatic and available whenever the sky is clear, wherever I happen to be located at the time.
