pmlogg

Allan Yes, the 5V to go from powerbank via usb cable to the Pi then by usb cable to the VM110. The Powerbank has 2x 2.1A USB, 2x 1.0A USB, one x 2oV 3A and one 12V 2.5A. The 20 and 12V have 2.5mm male power sockets. There is no separate ground connector. So the clamp could be disconnected, but the 12V connections would otherwise be as drawn before with the addition of 12V+ going to the Hall switch. I could use one of the other USB sockets of the Powerbank to directly power the encoder but I had planned on the connections from the rotary encoder and the Hall Switch coming together in a DB9 cable outside the enclosure for the VM110 + Pi + relay board and entering it by that single cable. Similarly a single usb cable from the Powerbank, outside the enclosure (so I can take it indoors for charging), entering the enclosure going to the Pi. Using a second USB socket using a chopped usb cable, all inside the enclosure would minimise cables in and out. The final cables in and out would be the pair coming from the lead acid battery and the pair going to the motor. If not going to clamp the +12V from the lead acid battery would just be going to two contacts on the relay board and to the Hall switch. I've now drawn the whole system in less the indoor computer and the magnet to mark home position. It looks a lot more complicated now but that is because of the addition of the two DPDT switches that isolate the existing Pulsar circuit board. When the switches are thrown the other way it's the new system that is isolated and the 'manual' system is on. I was going I hope that it all makes electronic and Lesvedome sense. Thanks Peter

Alan The diagram shows 12V+ going to clamp but that same connection going to DC+ on the relay board and + on the Encoder - so that would be +12V into it from the Lead Acid battery - so that's wrong; either I need 5V from another source, or with the buck converter added to the 12V circuit - as Hugh said. The clamp is not an output but it is on the +12V line from the battery. The solution you suggest is neat but is another draw on the 7Ah 12V battery rather than on the powerbank. I could though wire the Hall switch, needing 6-36V, that way. I have to have the Raspberry Pi running as it performs the vital function of the wifi data link between the remote computer running Lesvedome to the VM110 through its usb cable. So the VM110 will be getting 5V from it. All along I had thought that the encoder, relay input signal, and Hall Effect switch would draw power from the powerbank, through the conduit of the Raspberry Pi and VM110, which I guess was wrong. The thinking was to leave the 7Ah 12V battery just to power the motor via the relays - the main power draw. The connections that I've shown for the encoder were provided to me by another Lesvedome user, but re-reading that now I see his 5V + signal was not coming from the VM110 clamp but via another cable, source un-specified. Reference was made to the Chris Harrow diagram showing a 560 Ohm resistor but that it might have been for a 12V supply. So an external source would seem to be needed for the Encoder and if the VM110 doesn't supply power to it The Raspberry Pi will have at least 2 spare usb sockets, even if I used 2 to power the VM110. Another solution would be to use one of those to provide 5V to the encoder, rather than adding the buck converter. Thanks Peter

Alan Thanks again. The 12V shown in my diagram is the 7Ah lead acid battery that has been powering the Pulsar/Rigel System. To supply power to the VM110 my intention was for it to draw 5V via the usb cable connecting it to the Raspberry Pi. The Pi has multiple usb so if necessary I could use two to increase the current available - but I had not expected that the VM110 and components connected to it would draw that much power. The power supply to it is to be the large-capacity power bank. It can simultaneously supply 5V and 12V. Although my original thinking had been that it would supply just the 5V it would not be hard to have two cables running from it rather than one. The Clamp certainly confuses me and I'm not certain what the voltage out from it would be. If it's 5V that would be OK for the EM14 but not the Hall Switch needing 6-36V, so an step-up e.g. Pololu U3V50F9? would be needed or a no power Reed Switch instead of the Hall Switch. If it's supplying 12V then the Hall Switch would get what it needs but the Buck Converter to the EM14 is needed. I don't know which is the sounder solution.

Alan Many thanks for checking the circuit. I've made those changes and also added in the optical encoder. Based on other users comments and diagrams I've put it's + terminal to clamp but if that is 12V, from what Hugh wrote I need to add a buck converter to drop that down to 5V. I've not drawn that it. I've still not drawn in the Hall switch, leaving for the moment the reed switch from the circuit I copied from. The Hall Effect switch I have is 3 wire - with the positive (brown) and signal (black) showing potential across them when the magnet is sensed. The resistor links black and brown, as I've not tried it attached to the Velleman board I don't know if the resistor is needed or not.. It needs power in 6-36V so in replacing the Reed Switch with it, should Black go to Digital Input 1, Blue to Ground and Brown to Clamp? DomeWiringDiag9.bmp

Steve That makes sense, I was confused by references to 220V with some - but I guess that was just the line voltage for the alarm system to which it was fitted. Silly me! Peter

Steve Thanks for that on the Hall Effect Switch. Yes, I have added a resistor to the circuit. When I tried without it I got no signal, with the resistor the LED lights up and the full 12V passes through. I do find it confusing that the circuit diagrams for the Reed switch don't show any power coming into the sensor, just showing connections to 12V negative and Digital Input 2. Thanks Peter

Alan Thanks for that advice on the relays and switch. I've modified my original posted image, replacing the ELK relays with the Ebay one (showing just the connections). Do you think I have got those connections to Relays 1, 3 and 4 on the board right? I've not yet drawn in the Hall Switch. Thanks Peter

Hugh I have not used the Charles Harrow diagram for a couple of reasons. First it doesn't give me, as someone unfamiliar with the components, enough detail e.g. it shows the relays but not how to wire them up. Secondly it includes AC components which again confuses me as mine has to be all DC. Finally, when at this stage I just want to wire up for the non-manual control circuit the inclusion of the shutter control, scope power and manual control again just serve to confuse me as I've not been able to figure out which components and connections I can leave out. The diagram I posted is an edited form of one posted at this link: https://github.com/tonygilkerson/astrobagel/wiki/Observatory-Automation-with-LesveDomeNet. That showed me the actual connections and it was easier for me to edit out the manual control. It does not show the azimuth sensor but others have posted or told me how they connect their EM14 encoders and it conform with the connections o the Harrow diagram - so I've not shown that on the diagram, trying to stick just to the parts where I was confused. Likewise I left out all the connections to the Pulsar system. Do you disagree with the connections shown in the diagram I posted i.e. would that circuit not work? Views seem to very on the Hall Switches as you can see from the responses. I went for one for a couple of reasons. The main one was that most Reed Switches seemed to be based on mains power rather 12V DC. But I already had a working Hall Switch and magnets so I thought it worth trying. I may need a buck converter for it as it's voltage range is 6-36V so too high to just take 5V from the VM110. I do have the option to take 12V from the powerbank simultaneously with 5V. If the sensor doesn't perform then I can try what you suggest. On the encoder I changed from the first one I thought to use as it's connections were non-standard. I checked the Lesvedome spreadsheet and because my dome rotation is quite slow, and the EM14 version I've bought is 8ppr so I think it should be OK. I do need to resolve at least one issue and that is keeping the encoder wheel in full contact with the dome wall - at the moment it comes off during part of one quadrant. But that's a mechanical issue I think I can deal with. I have an enclosure that I bought when Maplin was closing down. It seems big enough for the components but as you say once I have them all I will tinker and if necessary get something else. I too have been very wary of drilling the dome. Pulsar tells me just to use a good bit, suitable for steel. Thanks for your advice to date. Peter

Hugh My original model of Pulsar 2.7m dome is already motorised, but not automated, with an original Pulsar-source 'Rigel' system, battery powered and fitted to the rotating part of the dome. It uses a 12V battery, which has a charging socket for solar powered charging. I really only use that for maintenance/trickle charging and instead charge from the mains in the dome after each session. The motor is a Parvalux PM4-LMS but I cannot at the moment find the specifics of its gearing and output speed. I suspect that it will be one of the lower speed models (e.g. 1500 rpm motor speed) as that draws less amps (5.4 full load) so more suitable for battery operation than the higher motor speed versions (16.5 amps full load for the 4000rpm version). The 4 relays on the Pulsar/Rigel Dome Controller board are Omron G5LE-1 1159W8. My intention is to retain that system as the 'manual rotation' vs. computer controlled system but to add Lesvedome control for slaving to the mount. My thinking is to use a pair of switches to isolate the Pulsar/Rigel controller board and switch the battery power and access to the motor to the Lesvedome system. One of the main issues was wireless communications to link the static computer with components on the dome. The solution I'm attempting for that is to add a Raspberry Pi 3B, powered by a 50,000mAh power bank, running VirtualHereCloudHub. That, with VirtualHere Client installed on the indoor computer provides wireless access to the usb port on the Raspberry Pi 3B and to the VM10 attached to it. So Lesvedome runs on the indoor and sees the remote, dome-mounted VM110 (same as K8055) as if it was directly attached by a usb cable. The Raspberry Pi needs no operating system nor ancillaries - it just runs the one program and performs a single function. That link has been tested and works. What that allows is a 'conventional' connection of the VM110 to the motor relays, optical encoder (Bourns EM14) and home position switch. If I decide to move on to shutter motorising and automation the dome mounted components for that could also be direct connected to the VM110 for Lesvedome control. I'm suffering somewhat from my deviations from the Lesvedome standard set up. I'd bought a cheap PCB mounted pair of relays that provide separate cable pair connections for CW and CCW commands - but the normal Lesvedome arrangement instead seems to use an SPDT relay (e.g. the ELK -912) and then a DPDT relay (e.g. the ELK-924) so it seems to me that I need to accept that I have the wrong relays and change either to the ELK ones, or similar, hence my question. Thanks for confirming the same relay board that Mike did. Could it replace both the dual relay ELK -924 (designate as a DPDT relay) and the ELK-912 SPDT relay? I'm also planning to use a Hall Effect Switch rather than Reed Switch. It's complication is that there are 3-wires rather than the two shown in most Lesvedome wiring diagrams. My presumption is that the negative, non-signal line could be connected to ground. Thanks Peter

Thanks for all that advice. A board solution was what I had in mind to minimise extra circuitry but I will look at those options. Peter

Mike I could call them but the stock is shown as being in the U.S. with the standard charge being applied. I agree the cost, for such small components is ridiculous. I have searched the RS site and can't see anything like the ESK components. It does surprise me given that they come up straight away on Ebay, from China of course. I'm still hoping someone may be know of a suitable equivalent to be had off the shelf in the UK. We'll see. Thanks, Peter

Mike Just went through as far as the Checkout - final cost with the shipping would be £46.97.

Mike Thanks for that. I see though that they would have to come from the US with a £15.95 shipping cost. My most recent attempt to buy from the US had mixed results. The parcel was rushed by FedEx Priority from Texas through other states, Paris and finally to Scotland but I missed the delivery, having only been told arriving by 6pm when I was already at work. It went back to the depot 40 miles away which then promptly shut not just for the 3-day bank holiday but added an extra day for good measure. So, if I could get an equivalent in the UK I would prefer it. I see relays listed on ebay that might do the job but my electronic knowledge is not good enough to differentiate which are good quality.

As part of my long-running project to automate my dome's rotation I think I may need to change plans again to bring the design more in line with what others have done, and in particular to use the relay arrangement set out in many of the circuit diagrams, a single relay board e.g. ELK 912 linked to a double relay board, e.g. ELK 924. However these two components only seem to be available from the U.S. Could anyone suggest equivalents for each that might be stocked by UK suppliers? Attached is a modified circuit diagram showing the relays, attached to a Velleman board, but with the manual rotation system left off.

Nigella Your dome looks similar to mine - a first generation Pulsar one. Another alternative to dome mounting the motor etc. is to emulate what Michael O'Connell did with his. If you haven't seen it already check this link: https://www.irishastronomy.org/kunena?view=topic&catid=22&id=95329#96208. He used off-the-shelf equipment sourced from Exploradome in the U.S. but the motors they supply are very expensive (but are also supposed to be very good). However the Exploradome track is not very expensive - and some have done DIY versions; same goes for the 'acorn' gear. So, a DIY combination using bought track and acorn gear with locally purchased motors would come in a lot cheaper. If you don't want to automate you could stop at that, just have a toggle switch to sent clockwise or counter clockwise. My motor system (an original Pulsar 'Rigel' one, for a 2.2m dome) is not as quick as just moving the dome by hand, but it is semi-automated so it will nudge itself around during an imaging session. That was primarily what I wanted to achieve but the aim I continue to work towards is slaving the dome to the mount. Seeing what others have done is getting me closer to that. Motorising or automating the shutter is even more taxing due to the two-part shutter but Michael O'Connell's system includes that too. Again a DIY version of that would be a lot less costly than buying from Exploradome. For it to be worthwhile to me it would need to be automated to shut in bad weather and that means weather sensors etc. plus confidence in its reliability. Michael has told me that despite incorporating all those features he still doesn't trust it to react quickly enough.

On flooring I used normal decking on a base of 2x4s. The flooring has gaps of around 5mm for ventilation which has only once resulted in me loosing anything but I have put a thin matt covering part, I can move it if doing anything where something might fall and be lost. The wood flooring always feels relatively warm, never cold like standing on concrete and I suspect better than rubber - but not as quiet. I have one decking board hinged so that I can easily get at the cabling underneath (another reason for raised flooring). My dehumidifier is controlled by an 'Inkbird' humidistat/thermostat (an recent upgrade from a simple timer). The dehumidifier has a pipe to drain outside. That normally works fine but sometimes the tank has filled, stopping the dehumidifier until it's cleared. I did once have a dim-witted slug think the pipe was a good place to hide - had to flush it out with water, so now I try to make sure the pipe end doesn't touch the ground. As the observatory is a dome there is natural ventilation between the fixed and rotating parts. In 7 years never had a serious damp problem. On wildlife I've not had anything trying to set up home other than a few spiders an occasional, lost slug. The door is a neat seal but not slug proof. The fiberglass walls are a bit slick for mice etc. to climb but slugs can manage that too! We do have bats in the area which I like to watch but I think they would favour a roost a lot higher than my dome. We get a lot of birds in our garden, with feeders right beside the dome. The wood pigeons like to perch on top and sometimes do what birds do; none have attempted to enter.

Ian It sounds as if you have put quite a lot thought into it already. When I was planning mine I read David Arditti's book 'Setting up a Small Observatory: From Concept to Construction'. It covers both dome and roll on roll off. I found several good pointers. One was to not make it too small - got to be able to get around the back of the telescope no matter what imagers etc. are fitted to it, without tripping over any features or items you might store in the observatory. Another was to have more power sockets than you think you will need. How to get power in has been discussed by a lot of threads but with your property being large it might be a limiting factor for you. One mistake I made was to not make the pier quite high enough so that the imager was at risk of striking the little top surface I'd built around it. That was made worse when I upgraded to a longer refractor. I've now made an extension but it's not as solid as the original pier - my next DIY task to resolve that!

Hugh Many thanks for that. I will think that through and either respond here or via a PM. Thanks Peter

Steve Thanks for your reply. I have Cat 5 from the PC indoors to inside the dome, along with cabling to a remote keyboard, mouse and monitor so that I can control the mount and cameras either locally or from indoors. The issue is that for observatory control the Velleman Card will need to be on the rotating part of the dome along with the rotation motor etc., all powered by the 12V battery. I need to establish a wireless link to its usb input and the options seemed to me to be either a dome mounted mini PC with low power consumption, e.g. a Compute Stick or a wireless usb hub. The 2nd alternative would remove the need for a 2nd PC but I've not been able to identify a currently available wireless hub that would work with a K8055/VM110. I don't know if the K8055/VM110 might alternatively be communicated with by an add-on Wifi card (but still powered by battery. Another, more complex solution, might perhaps be to add wireless relays, allowing the Velleman card to be on the non-rotating part of the dome, directly connected to the PC by usb. I know nothing about wireless relays but they seem to exist. Thanks, Peter

I've acquired a used Pulsar rotation system to provide the mechanical system but would like to modify it to allow computer control via Levesdome. I've read the interesting posts by others about power transfer to a motor on a rotating dome but instead I was minded to try to achieve it using the existing battery. From what I've read the Velleman board needs to be connected via its usb socket for communication as well as power. A wireless usb hub looked like a possibility but those currently available (please correct me if I'm wrong) seem to be very limited on what usb components they can be used with (printers and storage devices mainly). Another alternative would seem to be to have a compact dedicated computer equipped with wifi to act as the wireless usb hub. One of the Intel Compute Sticks, to connect via Windows Remote Desktop, seems like it might be an easier option for me than using a Raspberry Pi (but again correct me if I'm wrong) and compared with more capable mini-PCs be less power hungry. I've read that the early Compute Sticks were slow and Wifi not great but the Atom x5-z8300 version has two physical usb ports rather than just one plus more on the AC adapter on the m3/m5 versions, and it uses less power. My thoughts were that, if just using it for Levesdome and the connection to the main PC, it and the battery would be able to cope. Attached is a block diagram of what I mean. I would need to step down power from the battery's 12V DC to 5V. Any comments on that would be very welcome as I my electronic knowledge is very limited.