I'm not a electronics engineer/student, so please escuse me if my query sounds a bit naieve.

I have a Mp3+FM module (link) which I can power with a regular micro USB charger(or desktop USB). As the module cannot power a speaker I have attached a PAM8403 Class D Amp module (link) (i think it can take from 3.5 to 5.5 V).

To make this setup mobile I added a 18650 rechargable 3.7V 2200mAH battery (link) and a TP4056 1.2A 5V charging module(link). Now when I run the circuit with 5V external power attached to TP4056 it works well (thoe the volume is low and it takes few power cycles to start). But when I run it using only the battery, the module just keeps cycling the power (On/off..). Initial Setup (Diagram 1)

I thought as my battery is a bit underpowered and TP4056 only provides 4.2V power I can add a step-up converter. So I added MT3608 DC-DC Step Up Converter (link) and adjusted it to 5V, 7V & 8V but none of it seem to work. Can you please let me know if I had missed anything ? Circuit with StepUp converter

Unfortunately as I don't have any electronics background, I am not aware of how do debug (sorry for the software lingo) this issue. I do have a multimeter so I would really appreciate if anyone can point me in a right direction or jolt down some steps to do more investigation.

Update: As requested these are the power specs of the various modules:

  • MP3

Input Supply: 5V;
S/N: 65dB;
Distortion: 0.2%;
Output: 550 mV;

  • PAM 8403

3W Output at 10% THD with a 4Ω Load and 5V Power Supply;
Speaker With: 4~8ohms, recommended: 4ohms Speaker Power: 2~8W

  • TP 4056 Battery Charger

Based on TP4056 1A Standalone Linear Li-lon Battery Charger with Thermal Regulation chip;
Preset 4.2V Charge Voltage with 1.5% Accuracy;
2.9V Trickle Charge Threshold (TP4056);

  • MT3608 StepUp

Integrated 80mΩ Power MOSFET;
2V to 24V Input Voltage;
1.2MHz Fixed Switching Frequency;
Internal 4A Switch Current Limit;
Maximum Output Current: 2A;

  • \$\begingroup\$ 5V should be 5V – use a multimeter to verify your step up converter is actually supplying a stable 5V. \$\endgroup\$ – Marcus Müller Jan 5 at 18:56
  • \$\begingroup\$ Hi Marcus, thanks for the feedback. I checked the step-up by removing other modules (MP3 and amp) and it was providing steady 5V. I even tried to add the modules in series but the MP3 module just did not power on. \$\endgroup\$ – user3395453 Jan 5 at 19:06
  • \$\begingroup\$ adding the modules in series will not work. That's not how boost converters work. You even stand a good change of damaging things that way. \$\endgroup\$ – Marcus Müller Jan 5 at 21:15
  • \$\begingroup\$ You don't show your power connections for the amplifier or the rated output power of your step up converter, or the input power requirements of your MP3 and amplifier modules. Add all information for their power requirements. Your boost converter must be able to provide a solid 5V at full load so when you disconnect the load to measure, you confirmed only it's no load output. \$\endgroup\$ – K H Jan 6 at 1:08
  • \$\begingroup\$ If you have difficulties finding a sufficiently powerful boost converter with decent efficiency, consider adding a second 18650 and using a buck converter instead. \$\endgroup\$ – K H Jan 6 at 1:10

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