Published by Joey Joe Joe Jr on

The Jeffrey 2.0


Welcome to my iSpindel landing page. The official iSpindel home page is also a great resource for everything iSpindel.

What is an iSpindel?

An iSpindel is a digital hydrometer for measuring the specific gravity (or degrees Plato) of something you are fermenting. It connects to web services and uploads statistical information. The web service you connect the iSpindel to can graph the temperature and fermentation statistics without you having to physically disturb the fermenter. The iSpindel can work from inside a fridge or even a stainless steel fermenter.

The Printed Circut Board (PCB)

The Jeffrey 2.0
The Jeffrey 2.0

I suggest that you purchase The Jeffrey PCB version 2.1. Please use this link to register with to get a $5 discount and give me a referral. You can check out my blog post about the development of the PCB for more information on its features.

PCB from=From pcbway

Gerber files can be found on my GitHub page.

The schematic can be viewed in detail by clicking on the image below.

The schematic for the iSpindel / Jeffrey 2.0

Parts and Assembly

If you are using The Jeffrey PCB by Open Source Distilling you can use the below “Shopping List.”

The Assembly video for The Jeffery is found by clicking this link. This video can be used to assemble any version of The Jeffrey PCB.

Please note that in my build, The Jeffrey did NOT need additional weights added in order to get to 25° in pure water when the battery was installed at the lowest position. That being said, the ability to add weights and move the battery is still available if needed to fine turn the tilt in pure water. To see how to balance the iSpindel check out my video 25° angle in pure water.

If you are using iSpindel PCB 4.0 by CherryPhilip you can find use my assembly video and parts list from my blog post. Please make sure you remove the diode from the D1 mini as this step is missing from the “iSpindel PCB 4.0 by CherryPhilip” video but should be considered a required step.

Shopping List


Follow my video on how to load the iSpindel firmware.


There are different calibrations that need to happen in a specified order.

  1. Offset calibration
  2. 25° angle in pure water
  3. iSpindel formula calibration
  4. Battery voltage calibration (scroll down)

Connecting the iSpindel to a Service for Data Logging and Reporting

There are different options around this. Ubidots is a popular choice. I’ll also be exploring the TCP/IP Server for the Raspberry Pi.

Joey Joe Joe Jr

I was born on a pirate ship off the coast of Peru where I was given a traditional Aztec upbringing, during which I excelled in the arts of sciences. At age seven my parents accidentally murdered each other in a freak fencing accident. Heartbroken I joined the tribe of Omaha, where I trained under the legendary Vin Diesel. At age eighteen, after a failed Fear Factor audition, I set out for a berry plantation roughly four kilometers south of Albuquerque. I currently reside at Ram Ranch which really rocks!


jimdkc · February 16, 2020 at 11:14 PM

Yeeee! Haaaawwww! Been waiting for this board to become available. I have most of the parts in hand and I’m itchin’ to build!

    Joey Joe Joe Jr · February 18, 2020 at 9:40 AM


      Geep · March 31, 2020 at 5:29 PM

      I’ve been sheltered in place so long I might be missing something but I don’t see a shopping list, just a link to the PCB (and is the price show there per qty ordered? Ie $20 for 5 pcBs?)

        Joey Joe Joe Jr · April 2, 2020 at 10:23 AM

        Something happened to it. I think WordPress updated and I lost my ‘reusable blocks’. Anyways, I have rebuilt the shopping list and it should now be available again. I will review the list in detail later but I had to restore from a backed-up version. If any links are broken or you run into any issues let me know and I will respond.

        Thanks for bringing this to my attention, Geep!

Chris Denney · February 17, 2020 at 1:28 PM

Great work man. I’ve been learning about the iSpindel myself and trying my best to get one working. Finally got one working last night and only JUST discovered your work today. I’m curious though, why is the 25° tilt in pure water important? Mine is tilting like 50° in pure water but it’s giving me accurate measurements after I calibrated it.

    Joey Joe Joe Jr · February 18, 2020 at 9:32 AM

    I can’t say why, but the creator of the iSpindel, universam1, has stated multiple times that 20 to 30 degrees in pure water is a requirement, not a suggestion. I’ve seen him tell someone whos’ iSpindel floats in water at about 70 degrees that he would never get accurate results until he balanced his iSpindel in pure water. It’s awesome that you are getting accurate results! I haven’t done much testing around gravity readings yet as my original iSpindel had the firmware bug where offset calibration never saved, so my readings never made sense. I will do a second round of gravity calibrations in the future testing out the easy vs actualy fermentation methods. Thanks for your reply! How close does your iSpindel tie into a traditional hydrometer?

Henrik · February 18, 2020 at 4:12 AM

Great! Good job with the pcb, I’ll make an order soon 🙂
With my last iSpindel I used an app called BrewSpy and it worked for me. Could be an option if your to compare different data services.

    Joey Joe Joe Jr · February 18, 2020 at 9:40 AM

    Thanks for sharing. Do I plan on trying different data services! I’ve seen a similar phone app before. Can’t wait to try these out 🙂

Mat from Biarritz · March 6, 2020 at 1:30 PM


I was nearly pushing the order in pcbway until I see that the pcb is Size : 133 x 34 mm

The pcb is bigger than the geocatching pet 123 x d33 that you link. It’s the one I have already.

The size of philippo is Size : 123.24 x 30.7 mm

    Joey Joe Joe Jr · March 7, 2020 at 1:54 PM

    My PCB is designed not to fit in the pelting. It has ‘tabs’ that need to be filed down in order to get a snug fit.

    Please note too that I geocaching pet dimensions, 123 x d33, I posted are straight from the vendor. When I actually measure the opening with calipers, I get slightly different values. Use this link to get the right pelting for my project.

mat · March 7, 2020 at 4:29 AM


I was nearly pushing the order button on pcbway until I see the pcb size compare to the pet container.
The pcb Size is 133 x 34 mm
The ispindel_4.0 size 123.24 x 30.7 mm
And the geocatching you list are (internal), mm
~123 x d33
Did I miss something?

Thanks for your help.

    Joey Joe Joe Jr · March 7, 2020 at 1:49 PM

    My PCB is designed not to fit in the pelting. It has ‘tabs’ that need to be filed down in order to get a snug fit.

Mat · March 8, 2020 at 8:29 AM

Thanks a lot Joey.
I will order them.

Dannys · March 10, 2020 at 4:55 AM

Can you give me scematic board ispindel?

    Joey Joe Joe Jr · March 15, 2020 at 9:05 PM

    The schematic has been added to the page 🙂 Please check it out and let me know if you have any questions.

      jaisoh · March 20, 2020 at 3:40 AM

      Any possibility to get gerbers for the board or at least outline as dxf?

      I happen to have bunch of ESP-12F modules for which I was planning to do a board design. I’m intrigued about the snug fit of the PCB inside the tube and would like to leverage the outline you have done 🙂

        Joey Joe Joe Jr · March 30, 2020 at 10:54 PM

        Hi, sorry for the late reply. Things have been crazy with the virus, this and that. I dragged my feet getting the files out but here they are. It’s my first post in Github so let me know how it goes.

      jaisoh · March 26, 2020 at 1:36 AM

      Any possibility to get the outline of the board for example in dxf? Or the board gerbers?

        Joey Joe Joe Jr · March 30, 2020 at 10:57 PM

        Hey Jaisoh,

        Yeah man, here you go. Sorry for taking so long to reply to your other comment. Let me know if you need anything else. I put up the gerbers on Github but I’m unsure about dxf file format.

Jay · March 18, 2020 at 5:46 PM

Hi, I have ordered the boards and parts. I notice the 10K resistor is no longer listed on your parts list. Is it not really needed?

Thanks for putting all this together! I bet it was some work, especially from a pirate ship.


    Joey Joe Joe Jr · March 18, 2020 at 6:06 PM

    Yes, it’s not needed. 220k is the correct resistor, the official iSpindel documentation has a typo in it stating that it should be 230k, but in reality, it should be 220k.

    That being said, you can use 220k to 230k resistor and things will be fine. Resistors usually have a 1 to 5% accuracy anyways. The resistor is used to measure the battery voltage and there is a calibration method you can do to dial the iSpindel voltage into a reading from a multimeter. I will release a video on that calibration eventually but there is a link to it was well on this page.

      Jay · April 16, 2020 at 5:57 PM

      Hey Joey,

      I finally got the boards and all the parts! I assembled three of them so far, the first two had different troubles but the third is working out pretty well. I even have it fermenting in sugar water and updating ubidots! It is really nice.
      However it seems the temperature sensor is high by 2 degrees. I didn’t see a calibration procedure for temperature can you tell me how to calibrate the temperature sensor?
      Also, by the way, I am a little saddened that it don’t work in my fermentation chamber, an old freezer with temperature control. I really should have thought of that before I started. iSpindel is surrounded by a metal enclosure, silly me.
      Anyway it is a nice device on a nice board. Thanks for your hard work.


        Joey Joe Joe Jr · May 6, 2020 at 11:38 AM

        Hey Jay, Sorry for the late reply. Just noticed your comment now. I’m not aware of any way to calibrate the temp on the iSpindel but you should be able to do that adjustment in Ubidots. As far as the chest freezer for a fermentation chamber I have heard that it should work but you may need a wifi repeater close. You can use a phone app like Wifi Analyzer to test signal strength. I also found this post in a foreign language (you can use google translate to read it, link below) about making a wifi/radio relay with a regular coax cable. If you give it a try let me know, as I find this interesting but don’t have the ability to ferment in my chest freezer.


        Joey Joe Joe Jr.

Rhaski · April 10, 2020 at 5:45 PM

Nice PCB, Joe. I’m torn between this and v4.0 ispindel PCB for a bulk build. Because i’m in Australia and getting hold of keystone style battery holders is nigh impossible, I have ordered a heap of those two pin battery holders that look like this:
I just noticed in your latest video that you said that type is no good for your design.
Am i better off going with the 4.0 PCB or I can i simply trim this battery holder to make it work with yours?

    Joey Joe Joe Jr · April 13, 2020 at 11:29 AM

    Hi Rhaski, I can’t recommend the battery holders you purchased. The pins are too big to fit in the 4.0 PCB and are the wrong ones for The Jeffrey. The pins aren’t standard size and are larger. You may be able to file them down thin enough to use them with the 4.0 PCB. Good luck!

Clemens · April 20, 2020 at 1:25 AM

Hi Joe,
it’d be great if we can find an aliexpress link for the battery holder.

These should all work, right (single versions of course)?

    Joey Joe Joe Jr · April 20, 2020 at 5:25 PM

    Thanks Clemens! Those look good to me. Mine have Blossom on the bottom as well 🙂 I’m sure there is a single factory in China pumping them out like crazy.

Undefined Brewing [Chris] · May 9, 2020 at 11:44 AM

Wow thanks for all your hard work you put into this! I just ordered 20 boards in hopes to make a few of my own and ‘give’ some away.

Just a few things, the Wemos D1 mini does not have to match the exact one from Amazon with the “deep sleep” pads. As long as D0 and Reset are connected it has the ability to use deep sleep. Just make sure it’s Wemos D1 compatible board.

Also, I found a good supply of US sourced PET containers that would seem to work just fine (instead of having to have them shipped from the EU). I’ll follow-up when I test them out 🙂 They are about $0.40 each, and the caps are $0.05. Seems, they should just fit the boards height wise. they use the 38mm cap. Plus they come in all different colors, so you can match the boards ink screen 🙂

    Joey Joe Joe Jr · May 9, 2020 at 11:57 AM

    He Chris,

    Thanks for the kind words!

    Have you tried the D1 mini with the USB on the bottom? I would assume that it should be okay but haven’t had a chance to try it. I bought a lot of D1 minis now I have a bag of leftovers and can’t justify buying more.

    Super interested in the US-sourced PET containers. I’ve been working with some guys in Montreal (regarding making an iSpindel kit) about sourcing petlings from North America and they’ve been talking to China and Mexico. If required, I was thinking of making a North American version of the PCB to fit in the longer petlings found in North America (should be a small mod to the PCB design). Drop me an email at as I’d be interested in grabbing a sample petling for design purposes.

    Joey Joe Joe Jr.

      Undefined Brewing [Chris] · May 9, 2020 at 12:01 PM

      I haven’t ordered the Mini’s just yet, but, as long as they match the pin-out as the ones you linked they should be OK 🙂

      I’ll send you the info on the PET containers via email. You’ll see why they may require some finessing.

      Thanks again for all your hard work!

Undefined Brewing - Chris · May 15, 2020 at 9:35 AM

Hey Joe! I was wondering what you use to do the editing of the gerber files?


    Joey Joe Joe Jr · May 15, 2020 at 11:09 AM

    I use KiCAD to design and view Gerber files. KiCAD is free and open source. If you are looking just to view and measure Gerber files you can use something like this online viewer (I selected the old viewer that doesn’t require login).

      Chris Denney · May 15, 2020 at 11:54 AM

      Hi Joe. Do you publish the KiCAD files for customizing?

        Joey Joe Joe Jr · May 16, 2020 at 3:51 AM

        Hi Chris,

        Sorry I will not be releasing the KiCAD files for customizing as they have my name on it and I personally test each board design before releasing it to the community. The Gerber files are available on my GitHub and the schematic is posted on this page. If you want changes to the PCB I am more than happy to work with you to improve the design if it makes sense to make the changes. If you are interested in PCB design it’s pretty easy to get started. I’ve linked below to the video series that I watched to learn KiCAD.

        KiCAD Download:
        1st Video of Instructional Series:

        Yours Truly,

        Joey Joe Joe Jr.

          Chris Denney · May 16, 2020 at 6:19 AM

          Yeah, makes sense. I’m already quite familiar with KiCAD. In fact I was a guest speaker at the inaugural KiCon last year.

          I hadn’t realized you posted the schematic. That’s 90% of it. Sweet! Thanks Joe

          Joey Joe Joe Jr · May 16, 2020 at 10:49 AM

          My pleasure Chris. Keep me posted on your project as you make progress. I’m always interested to see what others are doing 🙂

Gregory · May 19, 2020 at 1:43 PM

Hi joey. Nice project you have done here.

Can you tell us a little more about your practical experience with it?
Does it really work like intended?
Are measurements precise and consistent in time?
How many hour do the ispindel works before a battery recharge is needed?

I would be very thankful if you could solve this concerns for me.

    Joey Joe Joe Jr · May 20, 2020 at 11:25 AM

    Hey Gregory,

    I have gone through the whole calibration process with a fermentation months ago only to realize that there was a bug in the firmware regarding offset calibration. I scrapped everything only to realized the 25 degree in pure water requirement. When I couldn’t get to 25 degrees in pure water with someone else’s PCB I started developing my own PCB. I have now fixed the 25 degree in pure water requirement with my PCB. Right now I have 4 iSpindels sitting in sugar wash and I’m going through the fermentation calibration process. It’s a slow process but we are getting there. Videos will follow. 25 degree video coming out this week.

    As far as accuracy goes, many people online say that the iSpindel gets within 1 to 2 specific gravity points. I will be doing my own accuracy tests in the future. Accuracy will be related to how well you calibrate the iSpindels. There are different methods of calibration that I will be testing as well.

    Battery life, I believe I did an update every 900 seconds (15 minutes) and the battery lasted longer than 3 weeks. The official iSpindel page states that you can get up to 3 months of battery life if you only update every 30 minutes. Really, how much resolution do you need on a fermentation process? Fermentation is usually done in less than 2 weeks.

    If you have any more questions let me know!


    Joey Joe Joe Jr.

Patrick McCarthy · May 24, 2020 at 11:03 AM

Hi Joey

I just want to ask if the circuit board ships to South africa?

Scott Sailor · May 28, 2020 at 8:38 PM

I received all the parts and look forward to assembly. Thanks for your great directions and video. I realize now that I purchased a IZOKEE D1 Mini. Looks similar but different layout a bit. Any suggestions figuring out which is the diode I need to remove? Thanks again.

    Joey Joe Joe Jr · May 28, 2020 at 9:08 PM

    Hey Scott,

    I have updated the assembly page. Link below. Go to the bottom and I believe that I have identified the diode. You follow the leftmost 5-volt trace on the USB to the diode. The pinout on that D1 mini is the same so it should work fine. I haven’t gotten around to getting this style of D1 mini as I originally bought an excess of the Wemos version. The USB is on the bottom instead of the top but I think it should work just fine. Please let me know how things go after your build as I want to promote this style of D1 mini but haven’t had a chance yet to try it for myself.

      Scott Sailor · May 30, 2020 at 8:48 AM

      Thank you so much. That is awesome.

    Joey Joe Joe Jr · May 28, 2020 at 10:59 PM

    You can also flash the firmware before removing the diode and before assembly.

Michael Deaves · May 30, 2020 at 2:50 PM

Amazing work Joey! I’m really stoked to get my build going.

I’m wondering if you have any info about sourcing the Petling containers in Canada. I’m in Toronto right now and can’t find them locally anywhere. Maybe we could import a bunch and provide a link for other Canadians to get them at a reasonable price?

Thanks again,


    Joey Joe Joe Jr · June 1, 2020 at 8:25 AM

    Hi Michael,

    I’ve had some back and forth with someone in Montreal regarding petlings. The lids aren’t right, and for The Jeffrey to fit in I may have to redesign the PCB. I’m looking for alternatives to what’s being currently used. I haven’t yet found anything that can be bought in small quantities at a reasonable price. I had centrifuge tubes on my radar but they come in packs of 50 and aren’t always cheap (and they are all different sizes). The search continues. The best bet is to buy the ones from the shopping list from Europe even though it’s not ideal for people in North America. If you happen to come across anything that you think would be a good fit let me know!

    Joey Joe Joe Jr.

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