AstroLink 4 mini device is a direct successor of AstroHub 3.0. Both AstroHub and AstroLink have its origins in my first project – JoloFocuser. Then after second version it become much more than just a focuser, that’s why I decided to change its name to AstroHub. AstroHub device has many capabilities, but it is pretty large. Plus name AstroHub turned out to be reserved. That’s why I decided first to do fourth generation in two sizes – mini and standard. And also change its name – that’s why AstroLink 4.
Version mini was developed in the first place. It is in relatively small casing (143x92x28 mm), lightweight (150g) and most of components are surface mounted. That’s why despite its modest dimensions it can still provide quite a lot of functions:
- can control focuser stepper motors in absolute way. Both unipolar (Robofocus, Moonlite, compatible) and bipolar and also microstepping resolution with additional module
- can control DC focuser motor
- has three switchable power outputs to supply any receiver like camera, mount or flatbox (up to 5A each)
- there are two regulated PWM outputs for dewcap heaters or peltier cooling (up to 40W each)
- two sensors can be connected to monitor temperature, humidity and dewpoint and also to regulate PWM outputs
- there is one regulated 3-10V voltage output
- plus device can monitor voltage and current drawn and also energy consumed (for battery powered setups)
- there are many alerts to define (temperature change, low/high voltage and power) plus fast overcurrent and overvoltage protection
- and five buttons hand controller is also available
Device requires DC power supply with voltage between 11 and 14V DC. Plus USB cable connection to computer, where dedicated AstroLink panel software can operate all device functions. Also ASCOM focuser driver is available. Focusing can be automated using any 3rd party ASCOM compatible software (like MaxIm, FocusMax, APT, SGP or any other). Both AstroLink panel and ASCOM focuser driver can work with the device in the same time – AstroLink ASCOM Local Server is responsible for this feature. INDI driver is also available, so all AstroLink 4 mini can operate under Linux environment.
Inside of AstroLink
Heart of AstroLink 4 mini S is well known Atmega328 chip. Communication to computer is provided with FTDI converter. All power outputs and motor controllers are based on modern LD MOS and MOSFET components. Switchable DC outputs can be loaded with 5A. PWM outputs can handle 3A current and motor outputs 1.2A maximum. Total current drawn from AstroLink 4 mini device cannot exceed 10A. Good quality power supply is recommended. There are several additional modules available for AstroLink 4 mini:
- five buttons hand controller – this one can move both connected motors in either direction plus motor speed can be changed
- microstepping motor controller – just needs to be connected to AstroLink 4 stepper output and can control bipolar steppers with resolution up to 1/32 steps
- power switch module – if 5A (or 3A for PWM) is to low value and you need more, you can use this module to switch more power loads. You need to connect it directly to power supply (can be the same power supply as AstroLink is connected to, or another one)
All these things are to make astroimagers’ life easier, limit the number of cables and control boxes in the astrophotography setup, so it will be more reliable as well. And AstroLink 4 mini version is really compact which makes it suitable for portable setups – when you power all setup with battery in the field, then it is good to know how much energy you already consumed and automate work of large energy loads like dewcap heaters.
There are more to come with full AstroLink 4 version – but it is too early to say exact specifications. But you are more than welcome to comment here with your wishes 🙂