Arduino based LDR volume and source selection controller

Instead of MOSFETs you can always use a diffamp as the current source. A part like the LT1990, INA154 (dual)

Silonex has an equation for fitting the response, or you can derive your own. In practice, you only need 3 points for a reasonable fit. You do have to measure, however, because the parts vary from piece to piece.
 
... the two first boards...

I will use the EA ASSEMBLY eDIP128B-6LWTP (touch, wake-up on I2C).
 

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Hello Vincent,

I´ve only one objection in your design: the use of the chinese display; it is not really long term availability and for some people really hard to purchase.

My idea is to modify your design by adding a LCD touchscreen display over the I2C interface (A4 and A5 pins from Arduino): one board with µC, LDR, IO´s interconnected with a 1mm ZIF connector, or other type, to a second board with supplies and LCD (the encoder is superfluous).

The candidate for this display would be from ELECTRONIC ASSEMBLY. I´ve used successfully this type of LCD with touchscreen in military application, but sorry, I´m not programmer!

They provide also OLED displays but in this case only over SPI.

ELECTRONIC ASSEMBLY - root LCD Module

Ok, you have to do some firmware modification to implement the LCD.

I know that a lot of people will then positivelly interested in a GB...

Regards,
Jean-Paul

Hello Jean-Paul,

The i2C 2004 LCD display is really easy to get and cheap - there are hundreds for sale on eBay or in Arduino-related online shops (LCD Display Blue 2004 (20x4) IIC, I2C, TWI )

But of course, any i2C display can be used, if you adapt the software.

You have a cool project going on, keep us updated!
 
There is an even better way to see the PCBs: you go to 3D Gerber Viewer | Mayhew Labs and you drag and drop the GERBER files in the viewer there (extract them from the .ZIP first). Then you can see a 3D rendering of the board!

Thanks Vincent. Looking over your design in more detail today this is a very generous contribution indeed to the DIY community! Excellent work!
 
... work in progress...

eDIP128B-6LWTP (with touchscreen); main power EMC filter and main power ON/OFF.

Fourth board in braining: RTC, elapsed time counter (super caps with charger), temperature sensor.

Missing something? I think about a current sensor? Anyone a schematics or tested circuit?
 

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... work in progress...

eDIP128B-6LWTP (with touchscreen); main power EMC filter and main power ON/OFF.

Fourth board in braining: RTC, elapsed time counter (super caps with charger), temperature sensor.

Missing something? I think about a current sensor? Anyone a schematics or tested circuit?

Is this the display you are intending to use JP? It looks very nice but about 90 USD is quite expensive?

EA EDIP128B-6LWTP Electronic Assembly GmbH | 1481-1106-ND | DigiKey
 

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Jean-Paul asked how the I/O relay contacts are wired - see the attached examples.

The schematics are the same for input and for output channels (only the labels change, from "out" to "in".

For 2 inputs (or outputs), only one relay is used for both.
For 3 or more I/O, one relay is used for each input or output.
 

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  • IO relay wiring 2ch.pdf
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... finished!

Can you check the schematics? I want to order PCB' s (without fourth board: needs from customers more options and features!)...
 

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  • LDR_LCD2004_REAR.png
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