• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Get free circuit help 24/7

  • +1000 Circuits
  • Hobby Circuits
  • Basic Circuits
  • Learn Arduino
  • Logic IC Pinouts
  • Disclaimer
You are here: Home / Audio Projects / Laughter Sound Simulator Circuit

Laughter Sound Simulator Circuit

Last Updated on October 8, 2019 by Swagatam Leave a Comment

As the name suggests, this device generates electronic sound, resembling human laughter.

BASIC DESIGN

To enable the circuit start the proposed operations, it must have a fundamental sound input or frequency for processing.

This basic frequency is established through a simple oscillator operating at 1 kHz frequency. The next, requirement would be to process this basic frequency through additional stages so that it imitates a human laughter sound. Please see the block diagram below for the details:

Due to the fact that, there's no "particular laughing sound" that may be followed in our electronic imitation circuit, hence the decision had to be an overall replica of most commonly heard laughter types.

Upon investigation, it was found that the majority of laughter sound felt like beginning at a specific stage within the sound range, which drops pretty fast to a frequency level approximately an octave lower. It can be compared to a soccer cheering heard in the reverse tone.

This sort of noise identified as a glissando) may be easily generated through the output voltage that comes from a basic integrator powered by a low frequency square wave oscillator which alters the voice generator frequency.

Also, the circuit must have the ability to make and break this characteristic in quite short bursts.

Each of these burst is supposed to cause a kind of warbling impact on the existing frequency with a declining frequency. To accomplish this an extra oscillator, named as the "giggle generator" has been included.

This stage continuously toggles the frequency of the basic "voice generator" from a single set position within the voice range to a new one. Once powered, the voltage from the integrator part of the "reversed cheer" generator is going to increase and decrease, creating a proportionate increase and decrease in the amplitude of the tone of voice.

However in case desired, the rising section of the tone may be prevented through a blanking gate network, as indicated in the above schematic block diagram.

How the Circuit Works

The Electronic Laugh simulator circuit works with three square wave astable oscillators. Except the part values of the individual astables which are adjusted with specific frequencies, the operating principle is simply identical. However the flip-flop (multivibrator) has a different functioning and we will learn more about it in the below given description.

Parts List

Please refer to the oscillator section in the "reversed cheer" generator stage of the above figure. As soon as power is switched ON, we could imagine TR1 switching ON and causing C1 junction at TR1 collector to be pulled at almost ground level.

Because of this, C1 that may have by now charged to nearly + supply potential, starts to discharge. During this period C2 swiftly charges up to the supply potential. When C1 has discharged to around 0.6V (i.e., the Vbe of TR2) TR2 begin to turn ON. Because of the feedback between the two sides of the circuit, a fast changeover takes place causing TR2 to turn ON intensely and TR1 to switch OFF.

This operation then goes on and on repeatedly with C2 discharging and C1 charging, until the time TR1 activates again and TR2 gets deactivated. This carries on infinitely, or until the circuit is powered off.

The C1, C2 discharge rates are primarily established with the values of R2 and R3, while the average time constant (1.4CR) decides the operating frequency. The charging intervals for C1 and C2 are dependent around the values of R1 and R4, that normally tend to be quite small and therefore may be simply ignored.

During the time when TR1 is cut off, the positive potential from its collector is allowed to freely charge the capacitor C5. This causes the voltage across C5 to rise towards the supply level while TR1 continues to be in the non-conducting state.

However, when TR1 gets the opportunity to turn ON, it causes D1 to get reverse-biased. Due to this C5 slowly discharges via R10, R11, R12, and the bases of TR5 and TR6.

This process in which C5 is charged and a discharged slowly, results in a constant variation of the voltage levels where C6 and C7 start discharging in the voice generator stage.

This impacts the average time constant of the frequency and consequently the output signal results also get affected.

This implies that the increase in the charging voltage across C5 does not cause a rising effect on the pitch of the signal.

The purpose of the "giggle generator" output is to momentarily force a quick switching of frequency of the "voice generator" while the "reversed cheer" is in action. This is successfully implemented by linking the collector of TR4, to the base of TR6 through R13.

BLANKING GATE

If you are interested to get a different kind of laughter simulation, this could be obtained by integrating a blanking gate network as shown in the above figure.

When this circuit stage is introduced, the voice generator functioning gets inhibited due to TR6 base being grounded, whenever TR7 is switched on. Meaning this allows, only the decreasing (discharging) action of the integrator on the "reversed -cheer" generator to perform at the output of the circuit.



SHARING IS CARING!



Previous: Photodiode, Phototransistor – Working and Application Circuits
Next: 10 Best Timer Circuits using IC 555

About Swagatam

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials.
If you have any circuit related query, you may interact through comments, I'll be most happy to help!

You'll also like:

  • 1.  Simple FM Radio Circuit Using a Single Transistor
  • 2.  How to Make a Telephone Amplifier Circuit
  • 3.  Arduino Musical Tune Generator Circuit
  • 4.  IC TDA 7560 Datasheet – 4 x 45W QUAD BRIDGE CAR RADIO AMPLIFIER PLUS HSD
  • 5.  How to Drive High Watt LEDs with Arduino
  • 6.  Balanced Microphone Preamplifier Circuit

Please Subscribe (Only if you are Genuinely Interested in our Newsletters)


 

Reader Interactions

Your Comments are too Valuable! But please see that they are related to the above article, and are not off-topic! Cancel reply

Your email address will not be published. Required fields are marked *

Primary Sidebar

Electronic Projects Categories

  • 3-Phase Power (15)
  • 324 IC Circuits (19)
  • 4017 IC Circuits (51)
  • 4060 IC Circuits (25)
  • 555 IC Circuits (94)
  • 741 IC Circuits (18)
  • Amplifiers (49)
  • Arduino Engineering Projects (82)
  • Audio Projects (85)
  • Battery Chargers (76)
  • Car and Motorcycle (88)
  • Datasheets (45)
  • Decorative Lighting (Diwali, Christmas) (32)
  • DIY LED Projects (82)
  • Electronic Components (97)
  • Electronic Devices and Circuit Theory (35)
  • Electronics Tutorial (100)
  • Fish Aquarium (5)
  • Free Energy (34)
  • Games (2)
  • GSM Projects (9)
  • Health Related (17)
  • Heater Controllers (24)
  • Home Electrical Circuits (98)
  • Incubator Related (6)
  • Industrial Electronics (27)
  • Infrared (IR) (39)
  • Inverter Circuits (94)
  • Laser Projects (10)
  • LM317/LM338 (21)
  • LM3915 IC (24)
  • Meters and Testers (55)
  • Mini Projects (153)
  • Motor Controller (65)
  • MPPT (7)
  • Oscillator Circuits (15)
  • PIR (Passive Infrared) (8)
  • Power Electronics (33)
  • Power Supply Circuits (65)
  • Radio Circuits (9)
  • Remote Control (46)
  • Security and Alarm (56)
  • Sensors and Detectors (116)
  • SG3525 IC (5)
  • Simple Circuits (72)
  • SMPS (29)
  • Solar Controllers (60)
  • Timer and Delay Relay (51)
  • TL494 IC (5)
  • Transformerless Power Supply (8)
  • Transmitter Circuits (39)
  • Ultrasonic Projects (12)
  • Water Level Controller (46)

Follow Homemade Circuits

Facebook
Twitter
YouTube
Instagram
My Facebook-Page
Quora

Feeds

Post RSS
Comment RSS

Circuit Calculators

  • AWG to Millimeter Converter
  • Battery Back up Time Calculator
  • Capacitance Reactance Calculator
  • IC 555 Astable Calculator
  • IC 555 Monostable Calculator
  • Inductance Calculator
  • LC Resonance Calculator
  • LM317, LM338, LM396 Calculator
  • Ohm’s Law Calculator
  • Phase Angle Phase Shift Calculator
  • Power Factor (PF) Calculator
  • Reactance Calculator
  • Small Signal Transistor(BJT) and Diode Quick Datasheet
  • Transistor Astable Calculator
  • Transistor base Resistor Calculator
  • Voltage Divider Calculator
  • Wire Current Calculator
  • Zener Diode Calculator
  • Privacy Policy
  • About Us
  • Contact
  • Disclaimer
  • Videos – Circuit Test Results

© 2021 · Swagatam Innovations