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.


For those that are reading this blog, thank you.  I suspect that I have about 15 actual views each month, the rest of the traffic to this site is probably attempts to advertise in the comment system. Please let me know if you find this blog useful or entertaining.

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