I can't figure out how to properly switch on the power on my GPD2846a decoder board with help of an Arduino Nano V3.
My project is a little box, that when unwrapped from wrapping paper, plays a sound file from the GPD2846a and lights up 1 yellow 5mm LED and 5 red 3mm LEDs in a blinking sequence. A Photoresistor is used as the trigger for the unwrapping.
The GPD2846a is powered with a 3,7V LiPo which works well if no switch is in between
The Nano is powered by 6V batteries (2xCR2025)
The LED-sequence just works fine
I tried following switches for connecting the LiPo to the MP3-decoder triggered by digitaloutput of the arduino.
Mosfet IRF520N (doesnt work at all)
Tranistor BC547 (worked when testing with UNO but won't work for Nano V3)
Optocoupler LTV4N35 (can power the GPD2846a but only periodical clilcking sound appears)
I was wondering if all the switches draw too much current so the decoder can not be powered by the LiPo anymore.
Can you pelase help me out finding a way to get this working, as you may have noticed im new to electronics.
Thank you for your help. If you need further information please tell me.
PS: I have very little space available (see picture)
And one thing I noticed is, that both arduinos only supply 3,7V on the digital output pin when powered by batteries, but close to 5V when powered by USB power supply.
Not a schematic. Switch to "schematic view" instead of "breadboard view" in Fritzing for the next version. But it gives a clear enough picture of the circuit.
The 5V regulators on both boards need around 1.5~2V above 5V to give 5V out. That's why you are seeing a low voltage.
Not sure why you are using two separate batteries for this project. Why bother with the coin cells of you have that Li-ion battery?
Those 5 red leds in series. Do they light? They shouldn't, if you really have wired them in series. They would need 9~10V to light them.
All red LEDs have an individual resistor (error in picture). I just found out, that the LiPo is fine for itself, just like you said.
I tried using an optocoupler to switch the play/pause button and have the mp3 module permanently powered instead, but this wont work as well. I think, that the module draws more than 100mA to be switched on or toggle play/pause. (see attached new "schematic")
I need a switch method, that can be toggled with 2,9V from arudion pin and can forward more than 100mA of current.
I don't understand any more what you are trying to do. I thought at first you were trying to save power by cutting the supply to the MP3 player module. But now I'm not sure. Does the MP3 module draw 100mA all the time? I would be surprised if that was true. Have you measured it's consumption, during playback and standby?
What is this optocoupler for? Why can't you control the MP3 module directly with an Arduino pin? I have used these DFPlayer mini modules before and connected them directly to a Wemos Mini, which is a 3.3V board. Is it because the digital pin's voltage is too low? If so, I would say the answer is to bypass the Nano's regulator. Connect the battery to the 5V pin instead of Vin.
Actually I managed to get it to work now. I control the play/pause with the BC547.
The working sketch is attached.
If it is possible to control it directly with arudino I have to give that a try, but since it is working now i would rather not change it again.
I would have preferred to find a way cut off the power from the board with a switch, as you understood correctly.
I don't have a DF player module this is the GDP2846A, it's different i guess. The problem is, that the MP3 module needs 3,7V minimum and every switch I used has a voltage drop and this i why it didn't work I guess.
You were lucky. I would advise anyone finding this thread not to follow your steps, as you clearly have no idea what you are doing. For example, your last diagram. Now the 5 red leds share a single resistor. In the previous diagram they each had their own resistor, which is the correct way. So you are going backwards in your learning process.
