Skywatcher AZ-EQ6 stalls during Go-To – Power supply issues

Earlier this year I got a lucky owner of a 10 inch carbon fiber newtonian telescope. The scope weighs in around 13kg. So I thought, this would fit perfectly within the capabilities of my AZ-EQ6 mount. Well, yes, by numbers (the AZ-EQ6 payload is 20kg), but not in my setup.
First of all, I had to add a third counter weight on the extension bar. So an overall counter weight of 15kg has to be added for these big scopes. Second, the mount became unreliable, as in Go-To movements, the mount stalled at some instances with a squeaking noise.
The noise is easily identified as the stepper motors skipping steps and not being able to drive the mount to the desired position. The mount won’t be harmed in any way. But the alignment will be gone for good. So you have to reset the mount and align with the sky again. Or, if this happens during alignment, you won’t be able to tell or teach the mount the actual sky model.

Additional information: Why do stepper motors skip steps?
A stepper motor, as built into the AZ-EQ6, consists of 2 static coils and a geared permanent magnet on the rotor. When the coils are powered in the right pattern, the generated magnetic field causes the rotor to move (in most cases 1.8° per full step). These coils are loaded in forward and reverse alternately. During the loading phase of a coil, the coil poses a resistance. This resistance limits the current. The possible current combined with a given voltage (supply voltage) defines the available power to load the coil and generate the magnetic field to move the rotor. How strong the magnetic field has to be is set by the inertia of the motor itself, the desired speed and the attached load. Loading the coil takes a bit of time (in the range of 100 microseconds to a few milliseconds). To achieve the desired movement (mechanical work in given time), a certain minimum of voltage, current and load time has to be provided.
If at least one of the parameters does not meet the requirements, the motor will not be able to fulfill the movement. So the stepper motor will not fully move to the next step “position”. When the motor controller begins to change the supply pattern of the coils before the rotor reaches a sufficient angle towards the next step position, the rotor might be pulled back towards the previous matching position. So the rotor will be trapped in a narrow range of steps, jumping back and forth.

I was driving the mount with a 12V 20A power supply at home. When on the mountain top, I used a 12V sealed lead acid gel battery. All was fine, using scopes with less than 10kg (and only 2 counter weigth discs). But with the 13kg scope and extra 5kg counter weight, I added too much inertia to the drive system. So, as I want to use the 10 inch scope with the AZ-EQ6, and the AZ-EQ6 has no option to reduce Go-To speed, there is only one option to improve the setup: increase the voltage!
The manual says, Input Voltage: 11-16V DC, 4A. I tested the mount with a lab power supply at 15V. The mount was happy with the provided power. Further more, all Go-To movements completed without and problem! Sollution found!
For home use, I could find a quite cheap 15V 4A supply (15V supplies are easier to find than 16V supplies). For mobile use, there is no reasonable power pack, providing 15V. So I purchased a powerful 120W DC-DC boost converter from 12V up to 15V, which will run from car- or other 12V battery. (This is a temporary setup, until my mobile lithium battery based astro power supply is ready to use)
Both supplies got their GX12-2 connector to be plugged in to the AZ-EQ6 supply terminal…

Combined charger and trigger cable for Sony mirrorless cameras like A6400

I often capture time lapse image sequences and do astrophotography. In both applications, a trigger cable and a proper means of powering the camera are essential. Keep in mind, that a fully charged battery usually lasts for no more than 3 hours.
At the moment, the only way to power a Sony mirrorless camera for a whole night or several hours is a dummy battery attached to a power supply (be it a mains power supply or a 7.2V battery driven sollution). With the release of the new models recently, like the A7III or A6400, the camera may also be powered through USB charger during image acquisition. (It may still be possible, that the battery drains, but far far less.)

This is really good news, as a USB power bank will provide the juice to run a whole night or even longer! But there arises one new problem: The external trigger remotes use the same USB port as it is used for charging.
This is possible, as Sony has created the so called Multiport some time back for use with their video cameras. The Multiport is an extended Micro-USB port with a second row of contacts. These contacts provide access to some control as well as audio and video output.

I did some research and came across Multiport connectors with solder pads for all 15 pins. See the pinout in the images at the end of the post.

Sony Multiport Adapter

With such connectors I was able to tailor a dual cable adapter, to charge and trigger the camera at the same time! I took a USB cable with male type A connector and a headphone extender cable with male 3.5mm plug. I chose both cables around 1m in length. This should be long enough in most use cases, but not too long to reduce charging performance.

Combined charger and trigger cable for Sony mirrorless cameras

The 3.5mm plug fits some of my trigger devices. All the others have 2.5mm plugs, for which I have adapter calbes in use. Most computer timer remotes with interchangeable camera plug sold, have a 2.5mm female audio jack. See attached image for the typical pinout.

Soldering the two cables to the tiny solder pads requires a steady hand and experience in soldering. The USB as well as the audio cables have quite thin wires (AWG26 to AWG28, which equals to 0.12 mm² to 0.08 mm²), except the USB power wires (AWG22 or AWG24 in quick charge cables, which equals to 0.32 mm² and 0.20 mm²). The wires are rather stiff. Therefore, aligning the wires to the solder pads may be tricky. It gets especially tricky, if the wires are exposed from the outer isolation for less than a centimeter.
Advice: Always check the finished cable for shorts and proper contact with a multimeter!

Soldered Multiport adapter with USB (bottom) and headphone (top) cables

To reduce wear, which may lead to wires breaking off the solder pads, I designed a connector housing / case. The housing holds the adapter as well as the cables in place. Furthermore, this is the only proper way to handle the connector upon pluggin to / unpluggin from the camera.
The connector case is 3D printed. I share the STL file on Thingiverse here:

Multiport adapter case – 3D model in 2 parts

This is a guide put together as reference for me. If you follow this description, you will do so on your own risk. I may not be held responsible for any damage or injury caused!

Battery replacement of Panasonic hair trimmer, Models ER1410 and similar with standard AA NiMH batteries

I own a Panasonic ER1410 hair trimmer. Unfortunately, after a few years of service, the batteries did no longer charge. I continued to use it in wired mode. But it is by far no comfort to have the cable dangling around. So after some time I decided to check for a battery replacement.
There are several offers for a set of replacement batteries available online. But these are quite expensive. Luckily the batteries are NiMH rechargable ones in AA / Mignon size. The only difference from the standard AA batteries is a pin like connector on both poles, which slide in a metal groove for contact. The design is replacement-friendly, as the batteries are not soldered to the PCB. Instead, there is a 2 slot battery carrier, designed for the pin like connectors.
When a standard AA rechargable battery is inserted to the battery carrier, the battery has not quite good contact. To fix this, use a set of pliers to bend the metal contacts a bit. The batteries will have sufficient contact and the hair trimmer will work well!

Here are the steps I had to follow:
1. remove trimmer cartrige
2. unscrew all 5 screws (see photo for positions)
3. remove black round part at charger connector
4. lift black bottom part
5. remove batteries and remember polarities!
6. bend metal contacts inwards with pliers until new batteries have firm contact
7. insert new 1.2V NiMH AA batteries (check polarity!)
8. close trimmer and fasten all 5 screws
9. test operation and charging

This is a guide put together as reference for me. If you follow this description, you will do so on your own risk. I will not be held responsible for any damage or injury caused by a DIY repair. Be aware, that using wrong batteries (i.e. non-rechargable, wrong type / Voltage, …) or batteries installed wrong may cause serious injuries and carry a high risk of fire!

Camera slider – night shot with inclined setup

After finishing the slider, I was eager to test the whole thing. To test the capabilities, I went for an inclined setup with 3,5m length and 1m height difference. Well, the footage proofs a good overall performance. But unfortunately the motor is not strong enough to drive the slider cart all too well uphill. OK. The motor is without reduction gear and the motor may drive the slider cart at up to 1,2m/s… So for inclined setups, I have to add a reduction gear / worm gear drive or counter-weight system…

Sequence 1: 10s exposures, going up. Slider stalls due to overload

Sequence 2: 1s exposures at high ISO (it was too late in the night 😉 ), going down

poor quality photo of the setup

Camera slider – build complete :-)

After several hours of designing, 3d printing, drilling, soldering and assembling, my camera slider is ready to use! All components are neatly packed within cases, so that the only wires visible are the power supply from the LiPo battery pack and the shutter release cable to the camera. I have several extensions in mind, like a pan-tilt unit. But for the moment, I will test and use the setup as is. The next improvements will be more on the firmware, for more features: non-linear movement, slow start, slow finish, pre-defined profiles, … for more impressive movies.


Now, concluding the build, I have the following parts in the final setup:

  •  12 U-groove wheels, matching the carbon fiber tubes (3D printed plus ball bearings)
  • 4 wheel carriages, each holding 3 U-groove wheels (3D printed)
  • 1 case for the microcontroller and motor driver (3D printed)
  • 1 case for shutter release, power supply and connectors (3D printed)
  • 1 hand-controller case (3D printed)
  • 1 battery bracket (3D printed)
  • 2 end-assemblies (5 parts each, 3D printed)
  • 2 supports (3 parts each, 3D printed)
  • 1 NEMA17 stepper motor
  • 1 A4988 stepper motor driver
  • 1 Arduino Nano (Atmel 328 microcontroller)
  • 1 4×20 LCD
  • 1 Joystick module
  • 1 DC-DC converter
  • 2 micro switches with long lever as end switches
  • GT2 10mm timing belt with wire reinforcement
  • 1 GT2 10mm 20 teeth pulley wheel
  • 4 GT2 10mm idler wheels
  • A whole bunch of M3 to M6 screws and nuts
  • 40x3mm flat aluminium
  • 30x50x3mm L-shaped aluminium
  • carbon fiber tubes

The project was really a fun to make. Even more, the resulting slider provides flexibility and transportability! I may configure the slider in any length, depending on the available tubes. The tubes I use, are 37cm in length and have aluminium screw-in adapters to fit one to the other. I have a bag, which I used as personal item in air travel. The bag holds the complete setup for up to 5 meters (exkluding tripods). The bag weighs in at approximately 5kg – so it is a light weight setup for the length possible.

Damascus knife – building the handle

A few weeks ago, I built a damaskus knife blade (see Damascus knive workshop). Now I finally had time to build the handle. Part of the delay accounted for the decision in material and design of the handle. After some serious research and window shopping, I found the perfect combination I would love to have: desert iron wood and silver.
Desert iron wood is a very dense and hard wood. The core parts have a deep red color with wonderful dark texture. But it is not at all easy to find a piece at reasonable prices. Luckily I found an online store, offering a block of desert iron wood with matching size and texture to my likings.
The bolster shall be like a cap, continuing the shape of the handle. As a material I use sterling silver.

The shape of the handle should become rather minimalistic. Further more, I wanted to have some resemblance to traditional Japanese handles. Therefore I chose a prolongued octagonal shape, which gradually gains a bit in height from the bolster to the end.

To build the handle, I started with the wood. I drilled a hole at the exact position to center the blade. Then I used small files to match the hole with the tang, which has a rectangular shape and is a bit off-centered to the rest of the blade. This was really time consuming, as the desert iron wood clogged the files within a few strokes. But finally, after a few hours of work, I had a perfect fit for the tang. I let approximately 5mm of the tang still protruding the handle, to have more strength in the final assembly by hammering the handle on to the blade.
The next step was to make the recessed front, where the bolster will fit in. I cut a line at exactly 10mm from the front edge. Then I filed away 1mm of wood, as I will use 1mm sheet sterling silver. From a strip of 11mm width I formed a ring with an octagonal shape matching the handle, using parallel pliers. The ring is soldered with hard sterling silver solder. After filing and sanding the edges to have perfectly flat sides, I cut a sheet of silver with a bit of excess border. The ring is soldered to the sheet, again using hard solder. After cleaning and filing away the excess material, I could drill and file the hole for the tang. This again was a bit time consuming, to create a perfect fit…

Finally, I sanded and polished the silver bolster, gave the desert iron wood a last fine sanding. Then I mixed a bit of epoxy with desert iron wood file dust. I added glue to the bolster and into the hole for the tang. So I would have a really strong bonding betreen all the parts. I hammered the bolster to the handle (which was only necessary for the final 2mm). Following immediately I inserted the knifes tang to the handle. Using a rubber hammer, I pushed the tang into the final position within the handle.
Meanwhile I set an oven to approximately 70° Celsius for increased strentgh and faster hardening of the epoxy. After cleaning away any excess epoxy with acetone, I set the whole knife in the oven for curing.

Hint: If there is any epoxy pushed out of the joints during curing, you may use a small soldering iron to work the exopy off the surface. The remaining thin film of epoxy may be removed with acetone. If you are careful, you will most likely have a scratch free surface afterwards!

The last thing to do is a thin coating of hard oil.
After more than 20 hours of work (including forging the blade), the knife is ready 🙂 The final result is a perfectly balanced knife due to the heavy wood handle. The center of balance lies exatly in front of the bolster. The blade will hopefully last for a very long time and provide perfect cuts due to approximately 56-58 HRC.

Motorized camera slider

For quite some time I would like to create night time movies in hyperlapses. For me, the most stunning results may be created by moving the camera along a linear path by the use of motorized sliders. Motorized sliders, which are more than 2 meters long, have an impressive price tag. Further more, these tools are bulky and heavy, especially when the setup attached to weighs in a few kilos.
Therefore I decided to build my own with a few goals in mind:

  • light weight
  • portable
  • variable length
  • suitable for a load of a few kilos
  • wider range of speeds
  • extendable for rotation axis
  • direct control for camera(s)

To achieve all or most of these goals, I came up with a design built around carbon fiber tubes with aluminum screw-in fixtures. Appropriate tubes may be built from scratch or are readily available for camera gimbals. I chose the camera gimbal extensions, as there is no big price difference to buying stock material. Further more, they come in a handy size of +/- 40cm in length.
The end supports will have to hold the tubes as well as a gear belt, along which the slider cart will be driven. For long setups, I created supports, to prevent bending and excessive stress to the tubes. Both types of support will have legs as well as tripod mount screw holes (3/8 UNC thread)
The slider cart consists of 4 blocks holding 3 pulley wheels each. The blocks are attached to a base plate (in test setup a plywood sheet). In the middle of the base plate lies the motor unit consisting of a steper motor and 4 guiding wheels to create enough tension for the gear belt to be driven by the motor.

All in all, the shopping list is really limited, as most parts were 3D-printed. What I had to purchase or use (most parts were already to be found in the workshop) was:

  • carbon fiber rods (at least 8)
  • 24 ball bearings type 626 2RS (6x19x6 mm)
  • GT2x10mm belt matching the desired length
  • GT2 20 tooth drive gear
  • 4 guide wheels without teeth for 10mm belt
  • 1 NEMA 14 stepper motor, <3V nominal voltage
  • several M5 and M6 screws, washers and nuts
  • 3/8 UNC thread taper
  • approximately 0.5m of 40x3mm Aluminum sheet
  • 25cm of 30x50x3mm Aluminum L shaped profile
  • Arduino, Stepper motor controller like A4988, 12-18V (lithium) battery
  • 1 can of rubber spray like Plasti-Dip (c)

Most of the time I spent was in CAD constructing the parts. Printing took about 3 days. The pulley wheels have to be sanded for a smooth surface before coating with rubber. The remaining time was spent in cutting, drilling and tapering the aluminum parts, before all parts could be attached together.

The first test run was more than pleasing. See for yourself:

The next thing to do is to create a control box with all the features implemented for every day use 🙂

Wooden tripod base for small telesope mounts


Picture 1 of 5

Several years ago I purchased my first telescope. The telescope had an EQ2 mount included. The EQ2 is an entry level mount, with an all in one mount and tripod base. The EQ2 served me for some time, until I got frustrated with the instability and bad and worn gears in my unit. So one day I replaced it with a goto mount. The last time I used it was for the 2006 solar eclipse in Turkey. Since then the whole thing had to sit and wait for a long time in the basement.
Several years passed until I added a Sky-Watcher Star Adventurer to my collection of gear (I am really happy with this little travel mount!). To use the Star Adventurer in its full extent, a sturdy tripod is required.
None of my photo tripods (neither aluminium nor carbon fiber) could provide a rigid platform to hold against the vibrations of wind or camera mirror flip. After reading several comments on tripods for the Star Adventurer, the direction was obvious to use a wooden tripod. I was already scanning the market for proper tripods, when I remembered the EQ2, which had quite a nice wooden tripod. The only problem to solve was, to replace the EQ2 head with a flat base. The base should provide a stable means to attach the Star Adventurer with one UNC 3/8 screw…

The design was straight forward: The construction exists of 2 parts. A 3-prongue base to attach to the tripod legs and a raised platform for the Star Adventurer. As I didn’t have a large enough piece of beech wood for the base, I used a 40mmx40mm beech wood block. The block was cut in 3 equal parts. These are mitered at 60°. On the other side, I rounded the top part (a rather aestetical finish) and drilled the hole for the bolt attaching the tripod leg.
The platform consists of one round disc of 40mm thick beech wood, which I cut out with a 100mm circular drill. The 4 parts were then glued together with 2 wooden pins joining each leg part, to enhance mechanical strength.
After drilling the required hole for the UNC 3/8 screw and the recessed hole for the screw head with washer, the whole part was sanded, cleaned and finished with hard oil. The platform top face received a rubber coating for a better hold of the Star Adventurer.

Parts used:
3x 40x40x100mm beech wood
1x 100x100x40mm beech wood (for platform)
6x 6mm wooden dowel