µC generates musical sounds:  04/15/99 EDN-Design Ideas / (Circuit / schematic design added 6/06) [Note:  File contains multiple circuits.  Scroll to find this one]  Many modern devices send audible signals to their operators to indicate some of the predetermined conditions or states of the system under control. To avoid annoying human sensibilities, these sounds should match the musical scale. Several chips on the market provide such sound capabilities; for example, a programmable sound generator or an ISD1016 voice messager. The circuit in Figure 1 does not use a dedicated sound generator but rather generates sounds using software routines. The circuit uses an inexpensive MC68H705J1A µC and saves additional expense by eliminating the need for a sound chip. In Figure 2a, a note represents the pitch of each musical tone; Figure 2b shows the duration of the tone....

2-Input Mixer:  As simple as it gets. The mixer consists of two transistor-based preAmplifiers. The first one (designated "Mike in") offers higher gain. it works well with a regular dynamic microphone. The second one can be used to control audio input from a tape recorder/CD player.  (Circuit / schematic design added 6/06)

2m   20m Transverter:  (Circuit / schematic design added 6/06)

9-Pin PC Serial Port to MIDI Synthesizer Interface Cable:  (Circuit / schematic design added 6/06)

Add Speech Encoding/Decoding to Your Design:  02/04/99 EDN-Design Ideas  / (Circuit / schematic design added 6/06)   Adding speech capabilities to a design can sometimes lead to complex algorithms and expensive DSPs or specialized audio chips. However, with the completion of a simplified adaptive differential pulse-code-modulation (ADPCM) algorithm, you can now implement these audio capabilities in low-cost 8-bit µCs, which typically have lower power consumption and cost than their DSP or audio-chip counterparts. A two-chip design is feasible by offloading the encoding and decoding tasks onto the µC as if it were a peripheral. Since 1991, the Interactive Multimedia Association (IMA) Digital Audio Technical Working Group (DATWG) has been working to define a cross-platform digital-audio exchange format. An inherent problem exists with the exchange of audio data...

Amiga MIDI Interface:  (Circuit / schematic design added 6/06)

AN-663: Sound Effects for the COP800 Family:  National Semiconductor - Application Note   (added 2/06)

Analog MIDI Synthesizer:  (Electronic circuit added 4/05)

AN-H43: HV857 EL Lamp Driver Circuits for Low Audible Noise Or:  Supertex Semiconductors (Circuit / schematic design added 6/06)

Apple Mac to MIDI Synthesizer Interface Cable:  (Circuit / schematic design added 6/06)

ASM 1 Analog Synthesizer Module:  (Electronic Schematic / circuit added 4/02)

Audible Train Approach Warning:  (Circuit / schematic design added 6/06)

Automatic School Bell:  (Electronic circuit design added 02/05)

Birdie Doorbell Ringer:  (Circuit / schematic design added 6/06)

Canary Sound Effect:  Reverse engineered circuit diagram of a commercial Electronic Bird. This one was built into a plastic christmas ornament and runs off a 9V battery. Note that L1 is actually just an audio transformer with an unused secondary winding.  (Electronic Circuit / Schematic added 10/04)

Car Back-up Alarm:  The brake lights of the automobile trigger this circuit on and off.  This save the annoyance of the alarm when it is not needed.  This is an older circuit which was published in Popular Electronics Magazine, but still a good circuit today. (Circuit / schematic design added 6/06)

Cuckoo sound Generator #2:  Agreeable, very close sound imitation - Suitable for sound effects, door-bells etc. (Circuit added 9/04)

Dog Whistle:  (added 3/-3)

Electronic Canary (Doorbell):  This circuit is a modified "Hartley Oscillator" with a couple extra parts.  T1, the LT700 (or equivalent, is a small center tapped (ct) audio transformer with an impedance of 1000 ohms at 1000 hertz.  The secondary of this transformer has an impedance of 8 ohms.  Usually noted as 1K:8 ct.  I tried a couple other models like the red and green types (taken out of a $5 made-in-china am pocket radio) and they both work good.  You may have to adjust the caps to get the sound... (Circuit / schematic design added 6/06)

Electronic Canary Sound Effect:  Reverse engineered circuit diagram of a commercial Electronic Bird. This one was built into a plastic christmas ornament and runs off a 9V battery. Note that L1 is actually just an audio transformer with an unused secondary winding.  (added 2/05)

Half rate speech coder (hr) multi-channel implementation on the ST122 DSP-mcu:  AN1998 ABS TRACT The purpose of This AppNote is to provide a detailed description of porting and an optimized implementation of a low bit rate speech coder based on the ETSI GSM-Half Rate (HR) vocoder implementation for the ST122 DSP-MCU architecture based... (Circuit / schematic design added 6/06)

Happy Birthday Singer solar engine:  Time-Controlled Solar Engine: The original Type 2 Solar Engine was based around the "Happy Birthday Singer" (HBS) chip that was pulled from the original Hallmark singing greeting cards. .   (Circuit / schematic design added 6/06)

HV857 EL Lamp Driver Circuits for Low Audible Noise Or:  Supertex Semiconductors (Circuit / schematic design added 6/06)

Is - 127 enhanced variable rate speech coder (evrc) multi-channel implementation on the ST122 DSP-mcu:  AN1997 ABS TRACT The purpose of This AppNote is to provide a detailed description of the Enhanced Variable Rate Coding (EVRC) vocoder, Speech Service Option 3. This AppNote also provides a detailed description of the EVRC vocoder multi-channel... (Circuit / schematic design added 6/06)

MIDI Drum Machine Analog Input Schematic:  (Electronic circuit added 4/05)

MIDI Drum machine project:  (Electronic circuit added 4/05)

Model Train Diesel and Horn Sound Module:  (Electronic Schematic / circuit added 4/02)

Noisemaking Circuits:  police siren (added 8/03)

Paradoxical sound synthesiser:  (Electronic Circuit / Schematic added 10/04)

Paradoxical Sound Synthesizer:  The main property of paradoxical sounds is that their frequency do not change when you go an octave higher   (Electronic circuit added 5/02)

Scanmate Audio Activated Recorded:  (Circuit / schematic design added 6/06)

Simple module gives voice to PC :  05/26/94 EDN Design Ideas /  (Circuit / schematic design added 6/06)

Sound Effects for the COP800 Family:  National Semiconductor - Application Note   (added 2/06)

Sound Effects Generator #1:  (Electronic Schematic / circuit added 4/02)

Sound Effects Generator #2:  (Electronic Schematic / circuit added 4/02)

Speech and dialler l3914A/16A and ST3917A/B:  (Circuit / schematic design added 6/06)

Speech Recognition using HM2007:  (Circuit / schematic design added 6/06)

Talking Phone Dial Monitor:  (Electronic circuit added 4/05)

Talking PIC   Based on SP0256:  (Electronic circuit added 4/05)

Talking YODProject (PIC16C84):  (Electronic circuit added 4/05)

Ultrasonic Dog Whistle:  (Electronic circuit design added 02/05)

Wave Multiplier for music Synthesizers:  (Electronic circuit added 4/05)