symmetal

Hi Pete, Your setup using the Anker USB3 hub looks fine. 🙂 I use the reputable brand power supplies as mentioned as they have a full data sheet giving full specifications which includes over voltage, short circuit and overload protection. The brick type supplies have less information available and often don't mention such features. The LED supply you mentioned does say it has those features but how reliable are those features. For led displays low noise and ripple is not a priority for the supply so it may be higher compared to others. An advantage of the open frame types is that the output voltage is adjustable over a small range, and at maximum setting is 13.8V for the 12V supplies which is useful. The open frame ones have a thick metal base plate which is meant to be mounted onto a metal surface to aid in heat dissapation when used near its maximum output. Although the brick type ones are generally smaller and in sealed plastic boxes which do run hot at full current, so for your usage where the current will be modest, using the box you mentioned should be OK. I have mounted mine in metal boxes like this one with the power supply screwed to the bottom plate and a panel meter along with fuses and connectors on the front plate. They also have ventilation holes. They aren't waterproof of course, though the one on my fixed pier is under a little roof on a wood frame screwed to the concrete pier, so has no direct water getting to it and the normal heat from operation prevents any dew forming. If used in the open with another mount I put it in a large Really Useful strong plastic box with the lid just resting on top to let the cables out along with a 4 way mains splitter and laptop PSU for polar aligning if needed. The PSW30 isn't waterproof either of course, so would need to be in a plastic box or similar anyway. Alan

Hi Pete, The Nevada PS-08 can supply 6A continuous, so as long as the total current of that supplied via banana plugs, added to that supplied via the cigar socket, is less than 6A you're fine. The two outputs are most likely wired in parallel internally anyway. There may be an internal 5A fuse just for the cigar socket but probably not. The 5A specified is just because these cigar connectors have a small contact area, so potentially a higher contact resistance on the centre pin, so are not suitable for higher currents. This would cause a voltage drop on the cigar output and possible burning of the centre contact if the current is significantly above 5A. I'm assuming you're hoping to power the 5V dew heaters from the powered USB hub. You really need the hub to have dedicated 'charging' outputs if you're expecting to supply 2A from a USB socket. A standard single USB2 outlet can only theoretically supply 0.5A, while a single USB3 outlet can supply 1.0A. If it's a USB hub with 5V power in rather than 12V, then the power adapter supplying it also needs to supply up to 4A for the dew straps plus whatever else is plugged into the hub. If it's a 12V power input hub with dedicated charging outputs specified at at least 2A, then you're fine. If you didn't already have the 5V dew straps, I would have recommended getting 12V ones as it saves all that hassle, and they take only half the current to deliver the same power. It's not recommended to run power supplies continuously near their specified rated output power and the Nevada PS-08 does run quite hot at 6A too, being a linear design. The supply that 7170 recommended gives you a better overhead margin on the current, and isn't expensive, so is worth considering. It's a switch mode supply off course, but having a 3 pin mains input with a connected earth means you're safe from the 'tingles'. 😉 I personally use open frame switch mode supplies like this from Meanwell, a known reputable company, and mount them in a metal enclosure so can't give personal advice on the brick style supplies, though other forum members can give their recommendations. It's always worth considering the Nevada PSW-30 or similar if you think you'll be expanding operations in the future, and you can afford it, as it future proofs you, and you don't need to worry about such things. 😀 Alan

Here's a very good and easy to understand explanation for the reasoning. It's written by a member on this forum and is is Dutch, but selecting 'translate to English' in google works perfectly. His conclusion for the optimal focal ratio is f# = 3 x pixel size in microns for a mono camera f# = 6 x pixel size in microns for a colour camera Alan

That's very impressive. I've made a couple of attempts at M45 but was never happy with them as the background looked like a smeary mess. I can see I needed a lot more integration time even though the subject itself is bright. The stars look small enough to me. 😀 Alan

Hi Adam, X would go to one of the 2 motor terminals, while Y would go to the other terminal. The snubber polarity isn't important, but you could connect X to motor +ve along with the +ve motor wire from your PCB, while Y would then connect to motor -ve along with the -ve motor wire from your PCB. Alan

This does suggest the wiring from the board to the motor is giving problems and is worth replacing. It may be the connector on the board is also giving a poor connection on the two motor pins so it may be worth soldering the new motor wires direct to the PCB tracks, perhaps via a 2-way in-line connector if you need to have to disconnect the board in the future. If the motor connections are making and breaking repeatly before getting a good enough connection to move the motor, this would cause repeated current surges through the motor windings and the breaking connection in particular will give rise to a succession of voltage spikes on the motor terminals due to the sudden collapse of the magnetic field in the motor. The motor is really a big inductor. The snubber circuit, mentioned previously, across the motor terminals is there to suppress these voltage spikes by absorbing the energy from the collapsing magnetic field. Maybe your snubber has failed, and the repeated voltage spikes are causing your 7805 regulator to eventually blow, as well as the capacitor, so you could fit another one across the two motor terminals like this , or something like this from ebay. These should significantly reduce any voltage spikes generated and probably save you having to add extra filtering in the 7805 supply. You want to install the snubber close to the motor itself not at the PCB end. So new motor wires and a snubber is your first step. 😀 Alan

No problem Adam. I'll look at the board layout and suggest where the components can be fitted, and get back to you. This suggests a motor problem or the wiring to the motor. The relays have been replaced so it's unlikely not them giving a poor connection on one of the contacts. It would be useful to measure the voltage on the 2 motor pins, MOT+ and MOT- on the exposed pins on the rear of connector J1. When the motor fails to move for a few seconds, see if 12V is still measured here. If it is still 12V then the motor or wiring to the motor is at fault. If it's significantly below 12V and there is still 12V measured on the BAT+ and BAT- pins on the same connector then there is a momentary high resistance path between the battery and that point, possibly a poor solder connection on the PCB. It's worth checking that, before proceeding with any other modifications. There would often be some blackening visible around the solder joint in that case due to localized heating. Alan

The 7805 doesn't look like it's heat stressed so I can only suggest voltage spikes from the motor are causing the failures. The 7805 failing on its own wouldn't have taken out the electrolytic. The 7805 should work up to 35V DC input. It's possible the suppression snubber on the motor itself has failed or become disconnected. If may be worth opening up the motor to have a look, if it's possible. Alternatively, to suppress voltage spikes, as well as the diode I mentioned, I suggest putting a LC filter in the 12V to the regulator like this. Ignore the horizontal line across the middle, I didn't move the mouse cursor off the diagram before grabbing it. 🤭 D2 should suppress any negative spikes being caused by the motor turning off. D1 should help anyway, but D2 will shunt it to ground. With C1 as 100uF the LC circuit starts suppressing AC voltage frequencies above 1000Hz. Using 1000uF it will start suppression above 250Hz. The danger in the voltage spikes will be the higher frequencies probably around 5kHz or more so the spike will be reduced to a gentle bump of maybe a volt or so at most rather than the 10s of volts which seem to be happening. I put 25V on the diagram, but a 35V or even 50V electroltic would be preferred. Here's a link to the inductor. Of course any inductor around this value capable of passing at least 1A will be fine. I normally use radial lead components but an axial one as shown may be better for you and this one looked suitable. Here's a link to a suitable ceramic capacitor. The circuit will work fine without it but it's an extra belt and braces. Ceramic capacitors are good at shunting high frequencies. Electrolytics have a built in self inductance, so are not so effective at high frequencies unless you pay more for special ones. If you use it put the ceramic as close to the regulator as you can. I tend to use Farnell or RS, but of course you can get components cheaper from other places if you wish. You could drill some holes in your PCB to mount the extra components if you have a dremel type drill with fine bits of 1mm or so. 🙂 As another thought, if you didn't want to add the extra components, you could disconnect the wire of D1 that's going to the PCB fuse and wire that disconnected end directly back to the battery with another wire and smaller fuse. The battery is actually a huge capacitor and any spikes on the motor 12V go back to the battery and then just the residual spike after the battery has suppressed it goes to your regulator. The possible drawback is that the ground on the board is also carrying voltage spikes so a separate ground path to the battery is also needed. This is not so easy to achieve as the ground is more interconnected on the board and is not so easy to isolate the motor ground from the electronics ground. Anyway, some food for thought Adam. 🙂 Alan

Your posted image is rather small so it's hard to be definate, but the other three corners look reasonable which implies more a possible tilt problem with the sensor. You can try altering the spacing distance to improve it in that corner, though it's likely the other corners will then start showing poor star shapes. Sensor tilt jigs have been widely talked about on the forum, and are fairly cheap to make, so it's worth checking the tilt is correct, ie no tilt, before making any other adjustments. Alan

I wouldn't think it caused any other harm. It's only there to help smooth the DC input to the regulator from any sudden changes on the 12V input due to the large current spikes when the motor turns on and off. I also notice there is no protection from the motor back emf visible in the circuit particularly from when the motor turns off. There may be an RC snubber (resistor and capacitor in series) across the motor terminals to reduce its effects. You can't put a diode across the motor terminals as the polarity changes when you change direction. You can put a reverse biased diode in the 12V going to the regulator, for example across the capacitor which has blown. It doesn't need to be a high power diode, a standard 1A rectifier diode will do. Also check the working voltage of the blown capacitor. It's safer to make this at least 25V and preferably 50V. It looks like a voltage spike may have caused the capacitor to break down and start to draw current leading to it overheating and blowing. Alan

No it shouldn't matter. The pattern caused by the pixels may well rotate about a different axis to the camera body, but you're only interested in the reflection from the cover slip on the sensor front. The cover moving side to side while rotating won't matter as it just reflects off a different part of the cover. As long as the cover is orthogonal, the visual reflection from the cover won't move during rotation, which is all you're checking for. Alan

Another excellent image gorann. 😀 Do you route the camera cables in a specific curve over the front plate to avoid any diffraction spikes? Alan

It's common for the contacts on the display ribbon cable to corrode over the years, leading to a poor connection and display failure. You can remove the cable from the connector by sliding up the two locking tabs indicated by about 2 mm allowing the ribbon cable to be pulled out. Applying some contact cleaner on the ribbon contacts with a cotton bud, or maybe just some isopropanol would help. I always also apply a small drop of ACF-50 with a toothpick, to any contacts on equipment which is being used outdoors as it's anti-corrosion and water repellant properties work very well, preventing further issues. Using a toothpick allows you to apply it carefully down the connector contacts as well without it spraying everywhere, if you had used it directly from the can. When replacing the ribbon cable ensure the locking tabs are still up, and after the cable has been inserted fully, push the two tabs back down to hold it in place. This may not be the reason for your problem but is worth trying as it's cheaper than replacing it. 🙂 Alan

An alternative method using Copy/paste is Load RGB image as normal. Hit Ctrl+3 To display Red Channel. Or go via Channels tab and select Red channel. Hit Ctrl+A or Menu Select/All to select all the image. Hit Ctrl+C or Menu Edit/Copy to copy it to clipboard. Hit Ctrl+N or Menu option File/New. The clipboard should be highlighted so click Create, or hit Enter to create blank image of clipboard size. Hit Ctrl+V or Menu Edit/Paste to paste the clipboard to the new image. Hit Ctrl+E or Menu Layer/Merge Layers to merge the newly pasted image with the blank background. Save new image. When you get used to the keyboard shortcuts it's very quick. 😀 Alan

The quickest way to extract channels is to Load the RGB image as normal. Click on 'Channels' tab. Click on the 4 horiz bars icon to the right of the Channels tab label and select 'Split Channels' from the drop down menu. Your image will be split into 3 separate images on screen. Then just save the Red titled image. This will be a greyscale image of just the red channel. As to why Photoshop is freezing suggests insufficient RAM and/or Disk Swap space. If you have more than one hard disk, in Edit/Preferences/Scratch Disks tick any unticked disks so Photoshop can use them too. You'll need to restart PS after doing this. Alan

Objects with Declinations higher than your latitude are always towards your North and cross the Northern Meridian twice a day. The Northern transit mentioned is the transit in which it's highest in the sky, but it's still North of you. NGC7129 has a Dec of 66 deg so from the UK falls into this catagory. 🙂 Alan

Tilt means the camera sensor is not square on to optical axis of the scope, and so all the edges of the image can't be in focus at the same time with one focuser position. The larger the sensor the more critical eliminating tilt becomes. For smaller sensors it may not be an issue. This topic shows a simple method of indicating any tilt, much easier than the trial and error method analysing star images. If the camera doesn't have tilt adjustment screws on the front plate of the camera, to alter the angle of the camera to the optical axis, then an external tilt adjuster can be inserted in the imaging train to do the same thing. If buying one make sure you get one with the right side threads to match your setup. Your 183 doesn't have built in tilt adjustment so either an M48 to M48 tilt aduster to fit on the rear of the Redcat, along with the M48 to M42 adapter supplied with the ZWO camera to fit it to the camera, or a M48 to M42 tilt adjuster where it can fit directly to the camera. With the Redcat a specified distance is required between the scope and camera to enable infinity focus to be reached so I would use an M48 to M48 tilt adjuster and M48 spacers as required reducing to M42 at the camera. If you need one and can afford it, the Gerd Neumann M48 tilt adjuster is worth getting as it's much easier to adjust when fitted in the imaging train, than the cheaper push/pull types. Alan

Your latest image Richard is a lot better as far as spacing goes. The centre is much more in focus. Here's the CCDI results. I didn't notice on your first post that you were at the recommended 55mm for the flattener. I assume you're using autofocus. If so it was offsetting the focus to try and get an overall 'best' focus and was including stars at the frame edge which are outside the corrected field. Increasing the FF spacing has seemingly made the autofocuser concentrate on the more central stars to your advantage. The improved range in FWHM figures reflect this. If your autofocus routine has an option to use the more central stars and ignore the edges then setting it at 55mm spacing may work OK. If not, increasing the spacing by another couple of mm may give a more optimum central area out to around APSC size. As others more familiar with this scope have said, the 0.7x reducer/flattener is only intended for APSC size sensors at most. If you crop your latest image to APSC size it looks fairly good. As mentioned, a flattener with less reduction will likely give better corner results than a 0.7x one. The bottom corners of the image are showing less coma than the top corners, indicating some tilt is present so gettting that right may improve things overall but as it stands you're stuck with coma in the corners. Alan

I think you have a combination of tilt, spacing and coma. The centre stars are significantly out of focus compared to the edges indicating a spacing error, along with the corner stars pointing towards the centre. The best shape/focus stars are at top centre. The corner star shapes are showing a lot of coma which is the main cause of their bad shape. With my 6200 I couldn't get good edge stars until I made the tilt test jig which worked wonders. With my FLT98 I now have good star shapes overall apart from the far right edge which shows some coma. Depending on how the camera is fitted to the filter wheel it may be impractical to use the tilt adjustment on the camera so a tilt adjuster before the filter wheel may be better and you can test the whole image train behind the flattener on the jig then as my post shows on the above thread. I spent a long time beforehand trying to adjust tilt looking at stars but with little success. 5 mins on the jig fixed it. Setting the FF distance to the recommended figure plus about 1.5mm for the glass in the way was all that was needed for correct spacing adjustment. I would have thought your scope design/price would not show as much coma as it does. With the tilt and spacing correct the coma should hopefully be at a minimum though it may have to sent off for an alignment check if you're still unhappy with it. Looking at the CCDI plots it's implying the tilt isn't bad and it's mainly a spacing issue. CCDI seems to ignore coma and reports on the star main FWHM figure. The pink areas are bad with black and dark blue the best stars, although the FWHM figures are high even for the 'best' stars. For some reason it doesn't give a Max FWHM on the 3D plot (lower image). Alan

No problem Adam. 😀 I didn't realize both images were taken at the same time on one mount. So it does look like there is some flexure between the scopes as the TAK stars are nicely round while the APM's oval stars are similar and all in the same direction. Things are never easy are they. 😦 Alan

Here they are Adam and I think you'll be happy. 😊 Compared to your original postings they're a big improvement. Both showing a similar symmetrical minimum fall off towards the corners. Note the difference in the min/max FWHM figures (2.5" to 3.1") compared to the originals (8" to 18"). CCDI didn't know the image scale from the tifs and assumed 1.26"/pixel so the stated FWHM are using that figure. The 3D views are symmetrical and pretty flat too. The APM is showing a tiny amount of residual tilt in the Y axis but is really not worth worrying about. Your image shows a bit of tracking error as all the stars are a little oval all over. I would say the spacing is correct. The top left and bottom right corner stars are showing a very slight coma like spread which is not really a spacing issue. The TAK indicates that your focuser chose to focus near the top left corner rather than nearer the centre so the centre stars are showing as being more out of focus compared to the edges. The difference is only from 3.88" to 4.57" FWHM, so slight but just noticible on the image. As I've mentioned before I don't know what the percentage curvature figures refer to and the manual doesn't really say either. 🤔 The tilt jigs are certainly doing their stuff. 😀 Alan

Under Settings/Updates/Advanced Options, there is the 'Pause updates' option where you can delay any updates being applied for up to 35 days by setting a date where they will resume. I think this option is only available with Win 10 Pro and not Home, so that option should be there for you. Alan

If the 12V connects before the ground then it's possible the device will find a temporary ground via a USB cable or maybe other metalwork in contact before it gets its proper XLR ground. While not desireable, as a USB cable or similar route will be higher resistance so leading to a momentary low 12V on the device just connected, I can't see this in itself causing fuses to blow. What value fuses have you used for the ones blowing, and powering what? Car blade fuses under 20A from the usual sources are almost certainly quick blow types so it may just be the initial power surge on connection eventually blowing them if they're too low. I use a 5A fuse for the mount and 3A fuses for the other items. Re-wiring the XLRs with conventional pin numbering is a good move though, if you have the inclination to do so. 🙂 Alan

What price for peace of mind though. 😉 Alan

The 071 has 4.78um pixels and the 6200 and 1600 are similar at 3.76 and 3.8um. The 178 had a similar pixel spacing to the 1600 but has 2.4um pixels. Although the 178 seemed to display a faint dot midway between the pixels too. All very interesting, particularly the central spots behaviours between cameras. No sign of clear weather for the moment so can't confirm whether my assumption for the cover slip location on the 1600 is correct. Alan