Gina

I modify my 28BYJ-48 stepper motors to run off the A4988 driver modules, just like the Nema 17. I use these for remote focus for my astro imaging. These motors come with centre-tapped coils with the centre-taps connected internally. We need the full coils without the centre-taps and these need to be separate so the internal link needs breaking and center-taps ignored. This in turn effectively changes a 5v rated motor to one that works fine with 12v. These photos show the coils and connection PCB taken out of the motor, to explain the process. (Don't jump straight in and take the motor apart, it isn't necessary.) The yellow and blue wires are one coil (or winding) and the orange and pink wires are the other. The red wire is no longer used and cut short for safety. At first I opened the motor casing to get at the connection PCB but it was very difficult to get everything back in so I decided to try and cut the PCB track without taking the motor apart. I carefully drilled a hole through the blue plastic connection cover to access the PCB where the strip wanted cutting through. Then I was able to take a very small screwdriver and scrape through the track without disturbing anything else. This is shown in the close-up photo below. As before the coils are orange-pink and yellow-blue. Do not connect the red wire. Note :- Seems not all motors use the same colour wires but the outer two wires are one coil and the inner two are the other. The middle wire is not used and should be cut short and insulated for safety.

Hi Mandy. Sorry for the late reply - not been here for a while. The Raspberry Pi 4 is rather different and needs treating differently. I haven't looked into this as yet as I am content with RPi 3 so far.

Measure up, design and 3D print your own if you have the kit.

\\\\\\\\\\\not as good as it looked here but but I got an hour's reasonable subs out of a 4 hour session so success...

Heavy! 🤣

Yes indeed.

Sorting out back focus for the Esprit 80ED Pro field flattener and OAG. Components are ASI 1600MM-Cool camera, ZWO EFW, 10mm extension ring, OAG, T2 to M43 adapter, Field Flattener, adapter, scope focuser. This gives exactly correct back focus for the flattener. Guide camera focus should also be about the same as the imaging camera.

Thank you.

Yes indeed.

Not the postman but DPD from FLO. Heavyweight and very strong, this should do what I want. 😀

240v AC up to 40A SSRs are readily available and run directly off logic levels. Smaller sizes too. I use mains voltage SSRs to power my 3D printer bed heaters but nothing like that much power. 1.2KW (5A) is the biggest.

Quite amazing!! 😮

Amazing print

Wonderful image! I too am working on this object - also called Simeis 147 and the Spaghetti Nebula. I have decent Ha but no OIII as yet as I'm waiting for a clear night with little or no moon. I have the equipment but need the weather and moon to cooperate! 135mm f2.5 very good lens (Asahi Super Takumar), Astrodon 3nm filters and ASI 1600MM-Cool camera on EQ8 mount.

I've got an anglepoise light with 3x magnifier which I use for close-up jobs like soldering. An essential tool in addition to reading glasses.

Magnificent!!

Update. Case with camera assembly and thermal jacket. Lid with hole for lens and dew heater in position. The space on the left will take the RPi with HAT and buck converter for the 5v RPi power. Dome placed on lid. Bottom view with waterblock.

This is the location.

NGC 7380, Bubble, Cave & Lobster in Ha. 135mm f2.5 Asahi Super Takumar lens, 3nm Astrodon filters in ZWO EFW, ASI 1600MM-Cool camera. FoV 10° x 7.5°. EQ8 mount, no guiding. 32 subs with gain of 180, 240s exposure and binned 2x2. Total integration time of just over 2 hours. Processed in PixInsight. I have more lights but need to take matching darks. Meanwhile I thought this was worth posting.

Had some thoughts. There's more to this than the Astroberry Focuser and KStars/Ekos settings. I use a 28BYJ-48 5V Stepper Motor modified to work with an A4988 driver module which is driven from the RPi GPIO. The stepper drives the the focus sleeve with a quadrant gear and pinion on the motor. These are an earlier rig but the latest is similar with a different lens and dew shield. Different filter wheel too, as it happens.

I haven't used a B mask for years! Here 's a screenshot. Sometimes the auto-focus doesn't work right and then I use manual focussing, using ROI in the imaging section and exposures of a few seconds, moving large amounts at first and going smaller as I approach focus. I use the Absolute Position and enter the focus count in the control box and click on Set to change focus.

I have a DIY remote controlled stepper motor focuser to drive the focus sleeve on the lens. The stepper is run off the controlling and capturing Raspberry Pi with the Astroberry Focuser INDI driver (the author of this is a member here). On my main indoors desktop KStars/Ekos controls focus either manually or with an auto-focus routine. This takes images, selects a square with the best stars and measures the focus HFR then adjusts the focus, producing a V curve from which it finds the best focus. I get a focus HFR of around 1.2 to 1.3 pixels.

Thank you Olly, I really appreciate your comment. The 3nm Astrodons are quite something, Roger. Thanks for your comment.

Found a few more Simeis147 light subs, calibrated, aligned and added to the stack then re-processed. This is the result.

Simeis 147 in Ha slightly cropped and custom stretched. 45x3m + 21x7.5m = 292.5m which is just under 5 hours. Binned 3x3, gain 300. Processed in PixInsight. 135mm f2.5 Asahi Super Takumar lens, 3nm Astrodon filters in ZWO EFW, ASI 1600MM-Cool camera. FoV 10° x 7.5°. EQ8 mount, no guiding.