Is there a MFP2 version that is powered by 5v/Direct from USB?

[Samuel Tumlad]

Hello, is there a build of MFP2 that is powered directly via USB? I'm trying to build a focuser for my camer lens. I would like it to have as few wires/power bricks connected to mains as possible (added that a Pegasus Powerbox is out of the budget) thus the requirement.

I found this from Cloudy Nights but it was way back in 2014 and instead of a Nano it used a Teensy (https://www.cloudynights.com/topic/466453-super-compact-electronic-focuser/).

I'd be very happy if someone can point me to the right direction and/or proper documentation/PDF if the build has already been done. Thanks.

[brownrb]

Hi Samuel
Sorry, there is no design here that runs off 5V USB. The issue is the current needed to power the controller and the motor, and USB connections cannot provide enough current for most applications.

I know some haved running the ULN2003 with 28BYJ-46 5V motor running off 5V USB, and sometimes it works.

The idea of running the focuser off 12v is pretty simple really - increased torque etc. If you are already supplying power to a camera or filterwheel etc, just use a simple Y splitter cable from the 12v going to the camera and then to the focuser unit.

Cheers
Robert

[Samuel Tumlad]

Hello Robert, thanks for the comment. Very new to the whole thing (and DIY electronics really).

Another question does MFP support the TMC2225/2209? I found documentation in MFP2 but I haven't seen one in MFP even though it says on the homepage TMC2225/2209 are supported. I'd like to build one from stripboar/perfboard. Is there documentation for this that I can follow?

Clear skies,
Samuel

[brownrb]

Hi
The main pdf does outline the TNC2209/TMC2225 design and boards etc. The firmware zip file does have a folder that contains the code to make it go. The folders in the zip file are

myFP2_TMC2209SG-312
myFP2_TMC2225_312

In terms of complexity, there is
easy - uln2003, L298N, L293D, L9110S,
harder - drv8825, A4998, EASYDRIVER, RAPS128, ST6128
etc where current needs to be set correctly
then
hardest - tmcxxxx

The configuration and setup of the tmc22xxxx is more difficult when compared to other designs.

There are no stripboards for the tmcxxxx designs, only PCB versions, which are cheaper than you might think. If you are a member of an astronomy group in your area, you might be able to find someone in the group that can assist and share the costs.

IMHO, I do not think that the TMCxxx is worth the effort. It is more expensive, and a quiet motor really is not that of a big deal when one has an observatory and its running remotely.

I have a number of different controllers, the drv8825 ones are humming away years later and are still going without any adjustment over that time (since 2014 when I started this).

My personal favourite is the DRV8825 controller with touchscreen Nextion display.

I attach some documents etc for you.

regards
Robert

[David S Gamble]

You should be able to use the ULN2003 driver and a 28BYJ-48 stepper motor. Some Nano builds use a USB-C connection which provides plenty of power. This would be an extremely low cost build. I plan to give it a go!
Cheers

[David S Gamble]

I have built a focuser using a "Seeeduino Nano" USB3. It is attached to my SVBoney 106 using a toothed belt. The 28BYJ-48 has a 6 to 1 reduction buit in and the belt drive gives an additional reduction of 2.87. This equates to approximately 0.1 degrees per step. I initially hoped that the belt friction on the knurled helical focus would be sufficient but in the end I glued a strip of toothed belt onto the knob. I used a scrap of Vero board for the circuit , The wiring is very simple, 4 control wires from the Nano to the controler, plus ground and 5V to power the stepper. No additional components.

It works well. The stepper has plenty of torque and for less than $5 is easily relaced if it burns out. All up cost is less than $50

As discussed it does not require an additional power source and runs quite happily from the USB3 power supply

[David S Gamble]