Cost review

Newest SDK:

Espressif has moved the SDK to GitHub.  At this point, It is version 2.1.  I have no indication that they have done anything with the ADC Feature I requested.  I have not updated to this newest SDK yet. I will do that before I spend any time working on firmware.

New component costing:

The 74LVC2T45 level shifter chips are US $0.32 each in low quantities.  The PCA9306 I2C level shifter are about US $0.60 each in low quantities.  This results in the costs of the level shift components arount $1.50.  The original single part costs around US $1.25 each in low quantities.  This is not a big difference in cost but it does affect board space.

Design review:

I spent a significant amount of time this week studying the high voltage circuit with an eye to getting a more linear response curve to the sigma delta output.  I didn’t find a way to make it better so it stays as is.  I am thinking I want to control the voltage input to the voltage circuit so that I can reduce current when not being used.  Since I have the serial shift register, I can use one of it’s parallel outputs to control voltage to the high voltage generation circuit.

Side Projects:

I have a Heathkit SB-104-A that I bought many years ago with the Idea that I could fix it.  It has been sitting in my garage for all those years. I did a little research this week to see what I could do to go get it running.  To begin with, it needs four final transistors which are expensive and require some modifications of the system.

First thought is I should power it up without the Power Amplifier and test the rest of the system replacing any parts that have failed due to age. I could connect to the driver circuit to a dummy load to test the rest of the system.

I am a little “stumped” on the Arduino compass toy project.  I can’t get the display to work, not even light up in test mode.  I’ve had a few ideas about how to make a simple test jig so I could change displays quickly without damaging the solder connections.  I am taking an Autodesk Eagle class currently and this might become my project for the class.


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