====== Quad Delta-Sigma Board ======
2016-02-22

4x AD7190 + Arduino Nano \\
See also [[:ad7190|The ultra low noise 24-bit ADC: AD7190]]

This board implements a 4 channel, ultra low noise, simultaneous sampling, 24 bit ADC. It has a dedicated oscillator and the sync line is conneted to all 4 ADCs. Its indended use is to read out 4 strain gauge weighing cells in a 6-wire configuration.

With an external reference voltage it can be used for direct voltage measurements too.

The digital part is supplied by the USB-port, and the analog part must be supplied seperately from a low noise 5V power supply ([[:uln-power-supply|see Ultra Low Noise Linear Power Supply, using LT3042]]).

On each ADC only one out of two differential channels is used. See also [[:multi-delta-sigma|Mehrkanal Delta-Sigma ADCs und das Abtasttheorem]].
===== Top View =====

{{ :ad7190:quad-board-top.png?direct&600 |}}

===== Bottom View =====

{{ :ad7190:quad-board-bot.png?direct&600 |}}

===== Configuration =====
{{ :ad7190:2016-02-22_002.png?direct&600 |}}

===== Assembled Board =====
Here the blue wire was needed to supply the Arduino with 5V, because the USB-connector had an up-bent leg before soldering, and therefore the V+ pin was not connected to the Arduino-PCB. When I fixed this, I removed the blue wire. 
{{ :ad7190:dsc_1080.jpg?direct&300 |}}

R-Core transformer, 230V to 2x 9V. This type of transformer has the least capacitive coupling. It's good to avoid common mode currents. 
{{ :ad7190:dsc_1082.jpg?direct&300 |}}

Here a close up of the board:
{{ :ad7190:dsc_1084.jpg?direct&300 |}}

Between the transformer and the ADC-board there is the [[:uln-power-supply|Ultra Low Noise Linear Power Supply, using LT3042]]
{{ :ad7190:dsc_1085.jpg?direct&300 |}}

===== Downloads =====
  * {{:ad7190:kicad-quad-delta-sigma-1.0.7z|KiCad Project, V1.0}}
  * {{:ad7190:quad-delta-sigma-board-v1.0.pdf|Schematic, V1.0}}