Hi all
I am doing an add on for a home alarm system.
I bring power and signal with the same cable from the central unit to the Arduino Circuit. Basically I have an AI camera connected to the central unit that act as a sensor and I want to add an Arduino controlled speaker that say something before the alarm goes off.
Do you spot any major flaws in the design?
When the speaker is working the current draw doesn't exceed 0.2A and the speaker is supposed to work for several minutes just when the alarm goes off.
Thanks
p.s. I've used a trimmer in the voltage divider because I deal with alarm systems that give both 12V and 15V signal and power to my board.
p.p.s C1 and C2 should act as a filter against eventual noise picked up from the wires (some meters long) that connect the central unit to my board.
Unfortunately it doesn't work to magnify the schematics. Therefore I ask for what purpose and how You use that voltage divider. Too often V dividers are used wrongly.
I don't see the need for the 9volt supply.
Just use one 5volt supply,
and power the DFPlayer and the Nano with that, on the Nano's 5volt pin.
This is 2022.
78xx regulators belong in a museum. Buck converters are far more efficient.
Less heat, and current draw will be half of an 78xx, assuming your alarm uses a 12volt battery.
Leo..
Well, I thought that since there is a small current involved I could have used linear voltage regulators (moreover they are cheaper and smaller compared to buck regulator).
Ok so do you think I just can use 1 linear regulator (or buck) connected to the +5V pin, right?
If you ignore the big/expensive heatsink and the supply that has to deliver twice the current.
A 1Amp buck can be the same size as a TO-220 package.
With a classic Nano v3, yes.
Leo..
Rarely the case.
Only for really trivial currents. How much current does the DFplayer require?
Depending on the speaker impedance.
It has a class-AB bridge-mode amplifier that could draw 1Amp peak with a 4ohm speaker.
OP should mod the DFPlayer for reduced current draw when idle.
There are guides for that on the net.
Leo..
30 mA Stand-by, 40-50 mA playing, Using the internal DAC and further amplifying the L/R outputs, (without using the integrated amplifier).
I've opted for a buck module and a linear one to avoide switching noise and because I want to use this board with 12V and 15V input.
I have also used an opto to avoid a trimmer. It should work just fine...
I have an ERC error since I have connected 2 power output now. I think I can ignore it, right?
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