S@#t Happens. PHUT

I promised to post all the ups and downs… 2020 to 2022 were the worst years for sourcing components. The global chip shortage forced me to redesign some of Infinity’s modules. In particular, I had to replace the power op amps that drive the coils because I was unable to find the original components that were used in the Thor prototype.

The initial Thor prototype was thoroughly tested, with special attention paid to components that draw a lot of current. In one such test, I ran Thor continuously, sustain level at 10, for more than 24 hours while monitoring current draw and chip temperature. Everything is fine. The power op amps were operating at temperatures ranging from 40° C to 50° C, well below their rated limits. And it’s still holding up pretty well after more than two years of use.

This time, the replacement chip went up in smoke at power up, after a few cycles. At power up! The replacement chip was supposed to have the same power specifications as the original, but it failed spectacularly. Sigh.

For the tech-savvy: High efficiency class-D amplifiers would have been an obvious choice for driving the coils, but I try to avoid anything with high current, high-frequency switching components. The current flowing inside the guitar should be as clean as possible. Any noise can make its way back to the signal and can be audible after high gain stages further up the signal chain. I’m using class AB power op amps with hefty supply filtering in light of this.

Fortunately, after a quick search, I learned that the original chip I was using is once again available. Components that were previously unavailable are now back in stock. But now I must revert to my original design. This time, however, I’ll include heat sinks and a polyfuse for good measure. I am glad I made the Infinity system modular with 3 separate modules. 1. Infinity main board, 2. The MCU board, and 3. The Infinity coil driver board.

How difficult can it be, right? Just one more round of PCB assembly… Fingers crossed.

Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Inline Feedbacks
View all comments
Would love your thoughts, please comment.x