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Parts Challenges

Building organ consoles for use with Hauptwerk, adding MIDI to existing consoles, obtaining parts, ...
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jkinkennon

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Parts Challenges

PostMon Mar 07, 2022 12:44 pm

I suspect that any of us building more than a handful of MIDI Encoders and related hardware are having issues obtaining ordinary but essential ICs like the 74HC589A shift register. Even huge quantities are delayed until October. I would be interested in other's experiences and solutions. The equivalent output shift registers like the 595 are readily available.

The latest surprise has been the unavailability of the PJRC Teensy 3.5 and 3.6 boards where the Teensy 3.5 is a great choice for a matrix encoder as it is reasonably fast and is the last of the Teensys to run at 5v which is helpful for intermittent key contacts. In this case I am designing a PCB for the Teensy 4.1 and have a lot of Texas Instruments level shifters on order that feature a strong drive capability. This is the TXU0104 which is a newer improvement over the TXB variety. I'll certainly let people know the results in mid-April as these chips are delayed a little like everything else. Hopefully a matrix encoder is possible without going back to painfully slow devices.

I'm thinking of dropping one of my favorite Microchip 32-bit MCUs onto I/O boards as they have enough pins to do 64 inputs or outputs and would be relatively affordable. Other thoughts? While I'm now a "vendor" I remain interested in sharing a lot of my work. A bit of give and take regarding parts shortages could help all of us.
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larason2

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Re: Parts Challenges

PostMon Mar 07, 2022 10:19 pm

Why don’t you reprogram your boards to use the 595’s? They are both 16 DIP’s, and the pin outs look compatible.
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Doug S.

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Re: Parts Challenges

PostTue Mar 08, 2022 1:09 am

An electronics wizard friend has scored salvaged chips on eBay.
Doug
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jkinkennon

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Re: Parts Challenges

PostTue Mar 08, 2022 1:12 am

larason2 wrote:Why don’t you reprogram your boards to use the 595’s?


The 74HC595A is serial in and out, parallel outputs while the 74HC589A is parallel load (inputs) and the same serial in and out. I do use both IC's where needed.

I'm also experimenting with LVDT which if memory serves is Low Voltage Differential Transport which keeps SPI signals more immune to noise in longer runs. This makes it easy to run 10Mhz SPI reliably from one end of a console to the other instead of just a few inches to a foot or two. Another advantage is that it lends itself to the use of FFC (flex) cables which saves a lot of wire stripping and crimping making cables. Sure wish it were easier to post a photo here.
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ldeutsch

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Re: Parts Challenges

PostTue Mar 08, 2022 12:58 pm

This just goes to show that eventually everything will show up on the Hauptwerk forum!

I had to go to my cache of old college textbooks and retrieve the"TTL Data Book" to fully understand this post. It brought back memories of the days when I did digital logic design myself. I eventually moved on to custom microelectronics design and eventually more esoteric things like radiation hardening for microelectronics.

These days, I purchase such subsystems and restrict myself to software - at least for organs!

In any case, thanks for the entertaining change-of-pace topic!

Les

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