High voltage analog IO for Box0

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Surprise! We have something to show you 🙂

Recently, [Ferix] (one of our beta tester) shared hardware design of Box0 shield on his github Repository.

3D design

Schematic

[Ferix] writes:

A breakout board for the Box0 so the Box0 is able to handle higher analog voltages With this it can handle -33 to +33V on the input and output -33V to +33V as well.

The hardware is simple, 2 switching power supplies to boost the 5V in to +-33V, possible +-35V After that 2 +-50V 50mA output capable opamps with a gain of 10 and a divide by 10 voltage devider so the analog inputs can handle +-33V as well

An USB port is added to supply the board with 5V as the 5V pin of the Box0 is unable to deliver enough current. A small example:

10mA at 35V means that, at 100% efficiency, 70mA is needed at 5V, in practise this figure is closer to 90mA With 2 opamps being capable of delivering 50mA a total of 100mA at 35V is required, meaning 900mA at 5V as input.

Current limit is implemented by using a 1A polyfuse, minimal but better then nothing.

His design is lm2733 for generating +33V and -33V for Analog out OpAmp’s.
And using voltage divider for analog in.

He is using an USB micro for more power.

[Ferix] has used KiCAD (Free/Open source PCB designing software) for designing his PCB.

What is on your mind?
You can install KiCAD, download Ferix repo, tweak the design for your needs, get it manufactured and do something wonderful – let us know what you did 🙂
You will also need a Box0 for using [Ferix] shield, for which you can sign up for the crowdfunding campign or get a beta tester board by contacting us at contact@madresistor.com.

We will write a follow up post when [Ferix] get the design into reality and share what he is upto!

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