Now Enhanced!

Spending 10 hours in making enhancements to my SpeakJet Speech Synthesizer Development System... PRICELESS! Just four days ago, I soldered up my completely SpeakJet speech synthesizer system on stripboard, but I was not done...

The Enhancements...

Today, I have done the following enhancements to my original design:

  1. Ceramic Capacitors for RFI/EMI noise filtering
  2. Added electrolytic capacitor to LM386
  3. LM386 pin 6: Moved from Vcc (5VDC) to Vin (9VDC)
  4. Address reset circuit to TTS256
  5. Added on-board Level Converter for 3V3-based microcontrollers
  6. Added diagnostic LEDs for serial TxD and RxD

My Fritzing Diagrams

My Optimal Circuit


This Fritzing diagram is a symbolic representation of the actual built circuit. The major parts are:

  • BeagleBone BlackBeagleBone Black
  • SpeakJet microcontroller
  • TTS256 microcontroller
  • LM386N-1LM386N-1 audio amplifier
  • L78L05L78L05 voltage regulator
My On-Board Level Converter


In reality, the output voltage is 2.94VDC, which is basically safe for 3V3-based microcontrollers. The on-board L78L05 voltage regulator prevent any excess current drain beyond 100 mA. Click HERE if you need help with resistor color codes.

The Source Code

Thanks for Reading!

Today, my modifications allowed me to have a universal SpeakJet development system, that allows for both, phonemes-to-speech and text-to-speech conversions. This is a speech synthesis project and has nothing to do with voice recognition. The intent of this project, is to be fully tangible; a speech synthesizer that can be felt with the hands. If you would like to encourage me in making more technical blog posts, such as this one, please consider making an optional monetary donation into my PayPal account. Anyways, thanks for reading and have a nice day!


Marcos "Kuya Marc" Miranda