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Forum Index : Microcontroller and PC projects : PicoMiteVGA - sound out

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PEnthymeme

Regular Member

Joined: 27/12/2023
Location: United Kingdom
Posts: 42
Posted: 03:43pm 15 May 2024
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Afternoon all

In my attempt to build a countdown timer (LEDs sorted) - I am moving onto the audio aspect.   The plan is for it to "tick" as it counts down and then play an "alarm".  

I am working using a 1second wav file of the "tick-toc" which is played as the LEDs countdown.  And likewise an "alarm.wav" to play at the end.  This part seems ok.

Where I'm at is the PWM > Audio out.

Two questions emerge:

(1) What is the simplest filter to use - fidelity doesn't really matter
(2) I want this to feed into powered speakers - will I be able to drive them directly or will I need an amplifier - have a few LM386 amp modules so could tinker with those.

The other route is one of those "MP3" boards I see on my fav Chineese site - but that seems like overkill for my use case.

The bigger plan is to hard code some default buttons - 1m, 2m, 5m, 15m on the countdown and bundle into a project box.

Whilst I mention PicoMiteVGA - will probably be plain old PicoMite it the final version.

Any pointers?

Px
 
hitsware2

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Joined: 03/08/2019
Location: United States
Posts: 713
Posted: 04:32pm 15 May 2024
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Simple R.C. should do .......

Will not need amp with powered speakers ..
my site
 
PEnthymeme

Regular Member

Joined: 27/12/2023
Location: United Kingdom
Posts: 42
Posted: 04:35pm 15 May 2024
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  hitsware2 said  Simple R.C. should do .......

Will not need amp with powered speakers ..


Thanks for the sanity check!

Px
 
Mixtel90

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Joined: 05/10/2019
Location: United Kingdom
Posts: 6783
Posted: 05:00pm 15 May 2024
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Whatever you do, don't connect a low impedance load directly to an IO pin. I would suggest a resistor of 270R minimum to protect the pin.

The simplest RC filter would probably be 1K series followed by 47nF to GND. Any load after that should total 1K or higher.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
stanleyella

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Joined: 25/06/2022
Location: United Kingdom
Posts: 2127
Posted: 05:23pm 15 May 2024
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https://europe1.discourse-cdn.com/arduino/original/4X/c/8/3/c832b7cb1cea80815e33fc2eec0b67de3f37f8d2.jpeg
 
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