1
\$\begingroup\$

I'm still pretty new with electronics and am working on my first multi-voltage circuit.

My circuit is powered by two A23 12V batteries in parallel. From this circuit, I want to power a short section of 12V LED lights (about 4 inches of these cuttable strips).

It will also power, in a parallel branch, an adafruit audio assembly, after a 5V voltage regulator. Here are the adafruit parts I'm using for the audio:

5V voltage regulator
Audio FX Mini Sound Board
Mono 2.5W Class D Audio Amplifier
Mono Enclosed Speaker - 3W 4 Ohm

The below schematic is my circuit essentially...

schematic

simulate this circuit – Schematic created using CircuitLab

The 12V LEDs light up and work just fine.
The audio circuit powers up, illuminating the "power on" LED as expected.
However, when I close the trigger circuit on the sound board to actually play the sound, it makes a tiny scratch on the speaker and then the whole circuit just blinks out.

I know that the audio circuit itself is all configured properly. If I disconnect it from the 12V circuit and just connect it to three AA batteries, it plays perfectly.

https://youtu.be/VyevfLwVU6Q - this is a quick video of how the audio sounds (properly) on the simple 4.5V circuit
https://youtu.be/0y5xfyxhmo8 - this is what it is doing when connected (downstream from the voltage regulator) on the 12V circuit
(pardon the vertical video, my phone was horizontal, not sure why it recorded vertically)

The wiring diagrams I found online for hooking up voltage regulators all showed capacitors on each side of the regulator, but they all also said that the capacitors helped to normalize fluctuations in A/C current, which my circuit is D/C.

Any idea what I am doing wrong with the 12V circuit, and why triggering the sound effects blinks the whole circuit out?

If there's any other information needed to help, let me know and I'll do my best to answer.

\$\endgroup\$
1
  • 2
    \$\begingroup\$ You need capacitors - the "AC fluctuations" are changes in current drawn even though you think of your circuit as "DC". You have a low impedance output so you will draw significant t current as you drive the speakers. Your regulator probably locks up. Input and output capacitors are essential. \$\endgroup\$
    – Floris
    Commented Oct 15, 2017 at 3:20

2 Answers 2

Reset to default
2
\$\begingroup\$

Your battery does not supply the current needed, and it's high ESR cause a significant voltage drop when you try. The A23 is a poor choice for your design.

\$\endgroup\$
5
  • \$\begingroup\$ So ... assuming the same equipment, a third (or maybe even fourth) A23 in parallel should fix the circuit as is? \$\endgroup\$
    – eidylon
    Commented Oct 15, 2017 at 1:44
  • \$\begingroup\$ And if I were to replace the A23, would you recommend something specific? It needs to fit inside a medium sized toy blaster, which is why I chose these originally, as they are compact. \$\endgroup\$
    – eidylon
    Commented Oct 15, 2017 at 1:45
  • 1
    \$\begingroup\$ Lithium batteries come in various shapes and would provide the current needed. Also try replacing the leds with 5V led strips. Making it so you only need one voltage. \$\endgroup\$
    – Passerby
    Commented Oct 15, 2017 at 1:49
  • 1
    \$\begingroup\$ First add some nice big decoupling capacitors as Floris says, they will reduce the ESR for short duration pulses. I'd suggest about 1000uF as a start. \$\endgroup\$
    – user16324
    Commented Oct 15, 2017 at 10:50
  • 1
    \$\begingroup\$ This wound up being half the issue. As some people had mentioned in other areas, it seemed the regulator was also unable to handle the needed current and shut down protectively. I had to upgrade both the regulator, and the batteries (12V of Lithium; a 9V and two AAs in series). Neither fix alone was enough, and it still had static. So I went the other route and downgraded to a 5V LED strip. Now the whole thing runs fine stepped down from just the 9V. Thank you! \$\endgroup\$
    – eidylon
    Commented Oct 25, 2017 at 2:28
0
\$\begingroup\$

the led strip need to be removed first because it might have consumed alot of current,if it still not work,check the audio output without the pam8302 amplifier.If the audio output is ok,connect it to and transistor or an operational amplifier.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.