PreenFM3 Headphone Output and power consumption question

[isoa]

First hello everyone as i recently made a PFM3 here : ) I'm still getting in touch with the new unit but as i'm finishing the enclosure design i have some questions:

-First: Headphone output. The info in the github is a bit weak. I did what Xavier said (bridge 12 to Aux . both jumpers, bridge VCC Aux, and connect AUX 1.2.G to my 3.5mm jack output) I do have headphone output and the quality with a 32 Ohm drivers is reasonable. What i would want to know is why Xavier specifies it would be better to connect a headphone amp rather than the direct headphones? It's because quality and power output restrictions? I would also want to know if its feasible to solder a stereo potentiometer to 1.2.G Aux outputs to be able to control the volume.

-Second: About the power consumption. I want to install inside the case an ESP8266 Wifi board with WLED software that would be able to power up lets say around 12 leds of WS28212b programable diodes. A nice colour touch to the milky white acrylic base i'm thinking. Will the RF wifi transmission of the ESP8266 affect the sound quality of the synth? And also, what is the power consumption of the PFM3? Where can i safely tap a 5V/GND line to power the ESP+LEDS setup? I'm powering my unit from the USB port, but i would likely tap this 5V source from anywhere in the board that feeds 5V independently if i power via USB or 9VDC barrel adaptor. The ESP8266+Led array should draw around 400-500ma so i don't know if i'm overdoing with this idea.

Thanks for this nice project. Happy user here

[Xavier]

Hi isoa,

- First : The aux output is a copy of the 1-2 output.
A simple op amp follower is wired to allow to add an aditional output without altering the main 1-2 output level.
The level is not very high so it's not ideal for headset. But if it works for you, that's fine.
Yes, you should be able to add a potentiometer to turn down the volume.
The idea was to put an headset amplifer there but finding one that works from GND/5V is not easy.

- Pfm3 consumption is  between 220ma and 280ma depending of your TFT.
The 9v->5v converter is done with 2 diodes + 7805.
So if you draw 500mA more from the 7805 it will get too hot.
In addition, Usb2 specification allow it to give 500mA of current.

A solution would be to use the 9V DcIn and to use a separate 9v->5v converter for your ESP8266+Led.
If you take the power from the DcIn Jumper, the current already went through a diode so it should be at 8V.
That can be a solution for you?

[isoa]

Thanks for that Xavier, that was all perfectly explained.

I've just ordered a stepdown converter for providing 5V to the ESP as you suggested. After all it is the safest option. One last question, the DCIN barrel input, it must be 9V straight? Is it possible to feed a different voltage and let the 7805 do the 5V conversion? I don't have 9V power supplies but i do have a lot of 12V ones.

Once my unit is fully finished i will post a video and pictures in the forum : )

Isoa

[lokki]

With 12v you will generate a lot of extra heat, which could be a problem without a heatsink...I am not even sure passive cooling will be enough at 12v