I built a small desktop power supply, which has profiles, and can output constant-current, or constant-voltage - from 0 to 48V.

This means that I can use it to charge batteries as well! I am using the same DC-DC converter from this Dave Jones video

Hardware

1. Drok 0-55V DC-DC converter
2. Mean Well LRS-100-48 48V 2.3A 
3. 3-pin plug and wires
4. 4mm banana plug connectors
5. 3D printed  enclosure : I tweaked a bunch of things here, most importantly the length of the box that houses the Mean Well PSU.

• User manual for the DC-DC converter
• Edit - beriberikix on Twitter pointed out that I can run open source firmware on the Drok module! github.com/kanflo/opendps
• I am building 2 such supplies, one will operate from 0-24v using a Mean Well LRS-150-24, and the other using the specs mentioned above. Here are some photos of the build -

I have been meaning to do this for a while, but was waiting for Conf 2021.1 to get done. Now that it's 2 weeks since that, I think it's time to begin work on this!

Rules 

1. We should curate a list of books. This is to give people time to buy/borrow them - and also because some books have a higher impact if you've read some other books before it. See the suggestions so far here
2. If there are exercises in the book, we should create a GitHub repo and solve them, discuss them, review them - together. If there are variants to the exercises that we can come up with, we should document and do those as well.
3. Every book reading should have a known list of people who are participating.
4. It's not necessary that all members of the Book Club should participate in all the readings - obviously.
5. After each logical section of the book - could be chapters, or something else - we document what we learned from it. IMO the best way to do this would be as a GitHub repo (the same that has the exercise). That way we have a standard way of discussing, reviewing, making changes, and preserving history.
6. We should do 1 book per month.

Do the rules above make sense? What did I miss? What seems extra?

Hola all!

I am pleased to announce the schedule for the inaugural Makerville Conf!

The event will be streamed live on YouTube - so do follow the Makerville channel!

I am in the process of building a portable server for a friend. The plan is to have 

• multiple Raspberry Pis
• rugged, portable enclosure
• fast storage
• active cooling

I am going to document the build in this, and a couple more future blog posts

You can find the evolving BoM here. There are 2 options that I am trying to document - one with battery backup for data, and one without.

Microcontroller

A cheap ATTiny will be responsible for

• power button and safe shutdown
• I2C master for communication between the Pis
• and most importantly - for fan control

Active cooling & Power

Given that this is going to be a portable server rig, I decided on using an active cooling solution as part of the case instead of relying on environmental conditions. I am using a 120mm fan with a standard 4 pin connector w/ PWM for speed control. This has some concerns that I am still working around - for example this will run on 12V. Nothing else on my system works on that voltage - RPi, PoE, microcontroller.

I decided to use PoE to power the Raspberry Pis as that would make reduce cable clutter. This complicates things on the cooling front - as there's already a fan on the official RPi foundation PoE HAT. 

Storage

I am using Crucial SSDs with a USB-SATA converter w/ UASP support. USB Attached SCSI Protocol is something that will give you faster I/O on the disk which costs practically the same. I intend to use the USB3 ports on the Pi4 for storage so this will most definitely matter.

Enclosure

I am thinking of using a design similar to the Mac Pro (trash can version). So the Pi4 will be vertical with the fan positioned at the bottom.

Conclusion

I am super excited for this as I think there's going to be a lot of portable server builds in my life and I'd like to set a great foundation for them :D

Let me know if you have any more ideas that I should incorporate in this! 

For example I am hoping to have a small OLED screen that I drive over I2C that shows the system status and some stats.

I am personally very okay with makerville.io taking it's own sweet time to have users. But I realized that there's no way to request an invite. So if you are someone who would like to join makerville.io, just send me a mail at anuj at makerville.io. A small introduction to what you do would help!

I decided to get the Prusa Mini recently for my home lab. Here's the breakout of how much I had to pay  -

44% feels okay for importing a really good FDM printer like the Prusa Mini,  but if I was getting a SLA printer like Prusa SL1 which starts at 1400$ - it would mean I end up paying over 2000$ for it. 

1. Wisdom related to manufacturing, production, supply chain, and design for physical products is localized. That's why the "Indian" constraint
2. I have been doing hardware for a bit now, and there's just so much to learn it's overwhelming at times. Starting and moderating a community of makers is one of my ways to make the learning a bit more accessible.
3. Meeting people at meetups and conferences is one of my favorite things to do. Bouncing ideas off each other on twitter as well is a close second. Given the constraints of a post-2020 world, I think places like this forum can help with quality community-building
4. I'd love to have a place to document my projects. Personal blogs feel like Cathedrals. A forum is closer to a Bazaar - which makes a lot more sense to me.

What about you - what do you think this community should be about?