PCB DESIGN - All In One v2.5 - 32 inputs with 74HC4851

[gastric]

With this version, if you do not use USB you have to provide external 5 volts power on the USB header

I thought the external power was 9V? Or is that just for the V2.7 board?

[Synthex]

With this version, if you do not use USB you have to provide external 5 volts power on the USB header

I thought the external power was 9V? Or is that just for the V2.7 board?

On V2.7 board, there is a 7805 IC (a 5 volts regulator).

[japi]

Synthex, now that the firmware handles the lcd brightness, is the 10k trimpot obsoleted? Or it has another function besides that?

[Synthex]

Synthex, now that the firmware handles the lcd brightness, is the 10k trimpot obsoleted? Or it has another function besides that?

You can replace the 10k trimpot by a 100nF capacitor and a 1.5k resistor to use the firmware lcd brightness control.

[japi]

Synthex, now that the firmware handles the lcd brightness, is the 10k trimpot obsoleted? Or it has another function besides that?

You can replace the 10k trimpot by a 100nF capacitor and a 1.5k resistor to use the firmware lcd brightness control.

Good
Can you elaborate on this? that may help making this work ?
How's the wiring / polarity / etc

Thanks!

[Synthex]

You must remove the trimpot.
Connect a capacitor of 100nF between 1 and 2.
Connect a resistor of 10k between 1 and 2 (optional).
Connect a resistor of 1k between 2 and 3.
You can mount this last resistor directly on the LCD display (pin 3 and pin 14).

Contrast_Modif.gif

[japi]

Thanks a lot!
What's the result of using or not the resistor you mention as optional?

[Synthex]

Thanks a lot!
What's the result of using or not the resistor you mention as optional?

It's "electronically" better to use it, but it's the same result.

[japi]

I see
Thanksssss!

[japi]

Sorry to bother, is the schematics for this board posted anywhere? i couldn't find it, there is for the 2.7 but it has differences with this. I have a short in my 2.5 build and would be nice to have the schematics for that board