Telex: Teletype expanders


wonder about that actual amount of devices(i imagine different devices contribute differently too)…
would TT+2xTXO+TXI+JUSTFRIENDS+1-2(possible future devices for i2c) sound like over the limit?(if not, maybe what would be approximate latency from end-to-end thinking of “worst” devices in that chain ends?)

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latency isn’t the issue. it’s bus traffic. you can put a ton of devices on the line provided care is taken with cable lengths etc.

you of course can always have multiple i2c busses that are isolated.

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Milestone Update

All reflow work for the TELEX expander build is complete.

Lots still to do before shipping - but this is a significant point in production. All of the SMD components are affixed to the boards.

Whew; that was a lot of work.

Next, I’m going to take care of the last bit of prep work that I need to do prior to assembly. A little bit of business travel this week will slow me down - but I should be able to continue to maintain the beginning of next month shipping date.

Then, it is time to start putting these things together and testing them. I’ll keep updating as I progress through this process.

Thanks to everyone for their support and patience!

TELEX Microsite | Ordering Process Details
Crazy Verbose Status + Timeline | Printable Command Reference



Check out that pile of component-filled TELEX PCBs - weighing 5.73 lbs



So, I’m thinking about getting into eurorack, and I’ve put together something in modulargrid… :wink:



@GoneCaving - damn funny!! I burst out laughing on my plane. :wink:

So - if you’ve been following the other threads, you will most likely be aware that in order to reliably connect more than 3-4 devices to your Teletype, a mechanism is needed to provide more “pull-up” on the ii bus. This can be accomplished by modifying your Teletype or by using an external bus board that provides the additional needed pull-up. (You can also hack the firmware on one of the Teensy on your expanders, but this is not recommended as it may put too much strain on the devices on your bus.)

There are now two powered DIY bus board options for the Teletype ecosystem that @tehn has kindly designed for the ii expansionist. One is designed to sit in your case and one is designed to mount on the back of your Teletype. I’m calling them the iiBusboard and the iiBackpack to keep myself sane.



I’m assuming that many who have reserved the pending expanders might like one of these puppies. They are DIY and quite simple to build - only 3 SMD parts that should be trivial to affix even for novices. That said, I’m also assuming that there are plenty of folks on the list for whom DIY isn’t their thing.

So - we need to figure out how to get these out there. I’ve added a couple of columns to the list for these peripherals. PM me if you will need one and indicate your preference. I’ll share the numbers in a few days and then we can figure out how to get this taken care of without delaying the expanders. :slight_smile:


A user's guide to i2c
A user's guide to i2c

If I could “heart” this post again, I would.

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That’s fair amount of PCBs, my guess is that this whole project scale went up quite beyond the initial expectations :slight_smile:
Thanks for info on ii bus problems and possible solutions, keep up the good work!

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do u have grayscale panels for this plz???/

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Thank you for the plain English and extraordinarily thoughtful description. Now if someone would just define “pull up” :slight_smile:

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Whew, and here I was thinking it was something I was unfamiliar with.



Perhaps closer to the mark:

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I’d suggest moving the TXi’s to the top row so patch cables aren’t obstructing the knobs :wink:



with the iiBackpack on the back of the teletype, will it still fit in an isms?

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yes! still only 35mm or so.



cool. definitely in for an iiBackpack.

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Off to the races with assembly! Did the first 3 of each module this weekend to kick off the process. Here they are - QC tests passed with flying colors:

Used an extra PCB flipped backwards with female headers to help with positioning the male headers on the back:

That made a tricky part of the process much easier!

There are a lot more to build and I will not be shipping until I’m done with the assembly and testing process. Also - these first six took a lot longer to assemble that I was expecting. Could be due to context switching between the units. Let’s see tomorrow when I start working to hit my daily quota while still going to work. :expressionless:



I am just about to order the parts for both modules and noticed that when using the mouser BOM posted above I got some parts that look the same (as the 470R resistor or the 1uf caps) but I got different devices in the cart at a different cost.

Is there something I miss about those doubles or can I just merge the two lists, add quantities up to 10 and get the cheapest resistors and caps I find as long as package sizes and values do fit?

It will be my first SMD soldering project and I don’t want to mess it up of course…



Apologies - you found some competing parts from different dev runs. Those are in my original BOM - but when I did my big order I coalesced them into the following:

470R - Mouser # 660-RN731JTTD4700B25
1u - Mouser # 581-06033C105KAT2A

I’ve updated the BOMs accordingly.

Please let me know if you have additional questions.

TELEX Microsite | Ordering Process Details
Crazy Verbose Status + Timeline | Printable Command Reference

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