Minimal components to build a cheapo sound toy, based off of vague observations looking inside a real sound toy.
- 1 x Super-cheap chip-on-board (COB) microcontroller (MCU)
- 1 x Ceramic capacitor for MCU power delocalized coupling
- 1 x Zener diode for MCU power
- 2 x Resistors for MCU power and low-pass filter
- 1 x Electrolytic capacitor for low-pass filter
- 1 x BJT transistor for speaker amplifier
- Possibly a few more resistors depending on specifics
And that’s all there is to it!
No need for low-pass filter circuits… since this is a toy, it can be designed so that all stored sounds are low-pass filtered before manufacturing, thereby eliminating the need for such circuitry. Not to mention, when the toy is designed only to drive a built-in speaker and not an external speaker, the only speaker at risk of being damaged by low-frequency sounds is the cheap internal toy’s speaker itself.