How often we receive a phone call and simply by listening our interlocutor … Or modify it even like a robot or a being from some another planet? The post explains a voice modulator circuit which will change or transform an individuals unique voice into a completely new form. Now the input flows to the output but with a 180° phase shift. For radical changes or special FX, you can use harmonizer / pitch changing, genre changer, pitch correction / autotune. The modulated audio from IC5 goes to power-amp IC6 via potentiometer R7, the volume control. So, to make a voice changer, all we need to do is take the signal from a microphone, alter its frequency spectrum, and put it out a loudspeaker. Required fields are marked *. The characteristic tone of every individuals voice is specifically unique in all circumstances. The Zenerdiode, LEDs and electrolytic capacitors are all installed correctly (so, not a polarity issue). D1 specially controls the supply voltage to a safe value HT8950 (below 2.8V) and R1 vibrato frequency fixed at 8 Hz, an estimated. In a voice-over circuit, the voice has a higher priority level than signal. Verify that the circuit is amplifying. The Circuit Concept. SPECIFICATIONS. While at first glance it looks like a bridge rectifier, closer scrutiny shows the diodes are not arranged to rectify. circuit design / schematics / tutorials / video. Using three-diode strings in the feedback path makes it a soft limiter, meaning that the corners of the wave tops are rounded. Note that the carrier current is a bipolar square wave (switches between +I and -I); you want those diodes to open and close quickly and cleanly. Here’s a top 5 of free VST effects for changing the voice : 1) Azurite multi voice chorus VST Speak into the microphone as you gradually increase the volume to a comfortable level. Specially, with every touch, move the speech spectrum S2 step up and S3 moves it a step down. Once I know the board design is okay, I solder the chips directly to the board. This can be done with a Wien-bridge circuit as shown in Figure SB4. In both situations, the series is constantly sustained, as proven in Figure 3. Copyright © 2021 T & L Publications. The HT8950 consists of, among other efficient blocks of an amplifier with internal polarization microphone, an A / D of 8 bits, a static RAM (SRAM) and a D / A converter 8 bits. Download now & discover the best modulator transformer for PC & Online Games. The voltage achieve of this amplifier, that may be an open loop is normally comparable to 2000, established R3 (feedback resistor) and R4 (input resistance), being of the order of 8.3 times. The power supply you use for this project should be well regulated. It is called as a Voice-over circuit. Recently, I came across a talking Dalek toy for sale on-line. It’s perfect for ASMR or video calls! This is a very versatile voice modulator circuit using IC HT8950A from Holtek Semiconductors. Make your voice sound like a robot or other odd beast. Make this Quadraphonic Sound System Circuit. The animated mouth comes from a VU circuit made from the transistors, diodes, and resistors, etc, which is also wired to an output of the voice changer. We can see some sort of pattern in Figure SB1, but how do we get our hands on it? Price may vary by color. There’s your ground bus. IC2 is a CD4027 dual JK flip-flop which divides the 555 output by four to produce a square wave. The planned digital voice changer circuit is merely created to make this happen for you, and quite much more. Such ICs are inexpensive, and no transformers are required. With the diode switches open, the output is Vout = [ RL / (RL + RS) ] x Vin » Vin. IC1 is a CMOS 555 timer chip running as an astable. Just like the rainbow of colors in white light, that collection of sine waves is the frequency spectrum of the signal. Rather, the diodes are used as switches. The circuit is taken from the datasheet of the IC, so it cannot be wrong, Your email address will not be published. Its output contains sum and difference frequencies only, which it achieves by multiplying the audio with a fixed frequency carrier. Great for parties, recordings, bands, and even prank phone calls, this voice changer makes your voice sound like a robot and can also add a vibrato effect to your voice. AV Voice Changer Software Diamond does not simply change your voice in real time. Some fun things you can do with this project are to put “LEAVE A MESSAGE OR YOU WILL BE EXTERMINATED!” on your answering machine or tell the neighbor “GET YOUR DOG OFF MY LAWN OR YOU WILL BE EXTERMINATED!” The possibilities are endless. Look for the usual suspects: Once you’re sure there are no obvious problems, measure the resistance from +V to ground. To mount the project in an enclosure, they must be replaced with panel-mounted types and connected back to the PCB with short lengths of hook-up wire. The 633 is relatively expensive ($8), but luckily, there are other ways to do it.    So in addition to AGC, we can add a little “fuzz” to our voice by clipping the peaks of the sine waves by using a limiter. Voice Changer … View In Digital Edition, One day back in the 1970s, I tuned to a public television station to see an oddly dressed man fighting off a swarm of evil looking robots. The consequence could be compared to that gained a playback speed of a vocal information recorded on a tape is increased or decreased, except that it does without influencing or distorting the sped of the speech, in addition on top of that it contributes two specific sound effects: vibrato and robot to a sample speech. After being caught by the microphone, the voice signal is employed on the internal amplifier HT8950 by way of R4 C2 network. It can also create what they call a “robot voice.” The schematic in Figure SB6 is adapted from the HT8590 datasheet. NV. Voice Changer project can be used to transpose or distort one’s voice by encoding the sound appearing at the Microphone input. It can provide an 8 Hz vibrato. Assuming you used sockets, pull the chips out one at a time. The simplest circuit I’ve seen for this vioce effect uses a 555 and an opto-isolator to chop the voice and give the robotic effect. Frequency Spectrum User can use 3 volts to 9 volts to drive this circuit. Tag: voice changer. Its output contains sum and difference frequencies only, which it achieves by multiplying the audio with a fixed frequency carrier. Voice changer is accomplished by sampling the input audio signals into … Soldering joints are all good. How can we do that? The carrier input supplies the diode current. This nifty minikit has a built-in microphone and a power amplifier with volume control. Power MOSFETs, VI Improves Experimentation, Synchronized Light Displays, USB Keyboard Input, Power MOSFETs, DIY Biotech, Pocket-Sized Altair Computer, High Voltage Halloween. A balanced modulator can be built in several ways. One answer is summed up by the word spectrum. Well, another diode switch type of circuit is a balanced bridge modulatoras shown in Figure 3. Daleks have a bizarre voice, and I thought it would be fun to build a voice-changer circuit to make me sound like one (see the sidebar on voice changer circuits). This project is built around AP8072 IC. The mixing done by a modulator is a non-linear process of multiplication. REMALL Recording Microphone with Voice Changer, Pop Filter, Tripod Stand, Studio Recording Mic Compatible with Computer Android Phone iPhone iPad Tablet Type C for YouTube Singing Live Streaming. A microphone converts voice into AC signals that we can observe with an oscilloscope. Resistors R5 and R7, as well as the capacitor C4, the biasing circumstances render the electret element.An amplified and limited in bandwidth time, the injected HT8950 voice signal to the A / D bits where internal 8 is digitized at a nominal sampling rate of 8Khz. Figure 4 is a schematic of the voice changer. Assuming all the diodes are closely matched and assuming the transformer center-taps are exactly in the middle, then the current from the carrier input will flow equally both ways from the middle of the transformers. If the short goes away, you’ve located the problem area. In accordance with a voice modulator technology from HOLTEK, this voice changer chip digitally processes the fed voice signal all the time. The Voice Changer Kit is available in the Nuts & Volts webstore. It can also record Skype calls including your changed voice . Tag Cloud. Privacy Policy | IC4 needs both positive and negative supply rails. All Rights Reserved | It does this by shifting the frequency spectrum involved with the voice therewith, upwards or downwards in seven incremental actions as well as the accompanying output is discovered as comparatively much thinner or thicker in its frequency. Capacitor C6 decouples the audio ground by creating a low impedance AC path to actual ground. This project has many separate parts, and a misstep with any one of them can stop the whole system from working. Voice Changer project can be used to transpose or distort one’s voice by encoding the sound appearing at the Microphone input. I used 0.022 µF to get a carrier frequency of about 50 Hz. Just click the link below to review your options, then click SUBSCRIBE to make a selection and place your order. For widening/thickening, or making choir like voices, you can use : chorus, voice multiplier, voice doubler, stereo wideners. Requires 9V battery and speaker(not included). The jumper mounts on a two-pin header soldered to the board. It was Tom Baker as Dr. Who saving the universe from the Daleks. The new voice will be different to the original voice tone and unrecognizable. NAME FUNCTION1 OSC1 input of the oscillator2 VIB input mode selector vibrato3 TGU step input selector UP4 TGD input selector step DOWN5 ROB Input Selector mode step ROBOT6 VSS negative supply line (GND)7 NC Not connected8 A0 output internal amplifier9 AIN input of the internal amplifier10 VDD Positive Power Line11 LED LAMP Output for volume12 AUDIO Audio Output13 VREF Reference voltage internal amplifier14 TS chip test input15 FVIB control output frequency vibrato16 OSC2 output of the oscillatorIn Figure 2, the schematic diagram of the digital voice changer proven. With a little research on the Internet (e.g., look up “Daleks” on Wikipedia), I found out that the Dalek voice is produced by mixing an actor’s voice with a fixed frequency sine wave in a ring modulator (also called a balanced modulator). That means there is no net flux in the transformers from the carrier, so it doesn’t couple to the output; the carrier is suppressed. To use a crystal type mic, IC4 would need to be reconfigured to supply some gain. Jim Stewart This project is built around AP8072 IC. After all, to make a voice changer we need to alter the pattern so it sounds like someone else spoke the words. This latest addition really cinches it! And why they are connected the way they are. Once changed to its analog form, the speech signal is carried out through C3 R8-network to a LM386 (IC2) amplifier, liable for helping the speaker (SPK1) which make it audible. Since we are using a single voltage to power the board, we need to create a separate audio ground at half the supply voltage. But back in 1807, a fellow named Joe Fourier wrote a paper showing that, mathematically, such complicated signals can be written as a sum of simple sine waves. Power is run separately to the input and power-amp sections to avoid feedback through the power rail. FREE Shipping by Amazon. With no current (Id = 0), rd is very high and the diode switch is open. The system is composed generally of a digital voice modulator and an audio amplifier, produced around respectively the chip IC1 (HT8950A) and IC2 (LM386I) the user's voice is grabbed by an electret microphone (MIC1) and reproduced generally or frequency offset in a dynamic speaker (SPK1). AGC circuits are commonly used in commercial two-way radio systems used by emergency person, Figure SB2 shows one way of making a compressor. It uses A/D conversion, digital delay, and then D/A conversion. How is it that we can recognize a person by their voice? 3.6 out of 5 stars 233. One of the cooler things you can do is changing a guy's voice to sound like a woman's. Ok, so i am at University and my projects is to design a voice effects circuit. Circuit Diagram and Description: This Voice Modulator Circuit is made by using LM358 op-amp and LM386 Audio Amplifier IC. (When used in a detector, it’s usually called a mixer.) Small Logic Gates — The building blocks of versatile digital circuits. From the latter, the speech signal goes to a D / A converter the 8-bit reset to its original analog form or shifted frequency spectrum. The output of IC4 goes to IC5, a CD4066 analog switch. There is a strip of copper near the edge of the board that connects to ground. 1,5 W) like the (not included). These multi-part series may be just what you need! Voicemod is a simple free voice changer for Windows to chat online. The layout of the component side is shown in Figure 7. Just completed a Velleman Voice Changer board, but it is not working. Daleks (shown here) are half-robot aliens that roll around saying things like “You will be exterminated!”. When assembling a newly designed PCB, I use sockets for the ICs in case I blow a chip due to a layout error. (I’ve learned the hard way that such protection is a good idea.) Soldering A Voice Changer Kit - The Learning Circuit - Duration: 10:13. element14 presents 13,090 views. The article clarifies a circuit which contains the potential to correct or transform an individuals unique voice into a whole new form. It’s also helpful to provide a convenient bus to connect the ground leads of multimeters and oscilloscopes. The input goes through a voltage divider formed by resistor R1 and rd, the dynamic resistance of the diode. When you subscribe to Nuts & Volts — Print Edition, unlike other magazines, you also get full access to our Digital Edition at no extra charge. TP1 allows you to connect a scope and look at the signal coming from a microphone. Adjusting the feedback sets the Q of the circuit, and that sets the bandwidth. Remember that the dynamic resistance (rd) of a diode is approximated by rd = 26 mV/Id. If the voice is present or the microphone is on, the other signal gets off immediately to provide the microphone audio to the speaker. Compression (This is a conceptual circuit; more is required to make it practical.). Enterprise . Potentiometer R1,R10_____10K 1/4W Resistors R2_____1K 1/4W Resistor R3_____50K 1/2W Trimmer Cermet or Carbon R4,R6,R7,R14___100K 1/4W Resistors R5_____47K 1/4W Resistor R8_____68K 1/4W Resistor R9_____2K2 1/2W Trimmer … Figure 3 is easier to build than Figure 2, but it still requires a transformer. You can use an IC such as the old LM1496 which was designed for this pu… By A DC supply is connected to tie-block TB1. With an automatic gain control (AGC) circuit, we can amplify a signal when it’s soft and attenuate it when it’s loud. The HT8950 “Voice Modulator” was designed to be used in voice changers. Clipping makes the sine waves look more like square waves, which adds high-frequency harmonics to the voice signal. Or, you could use a multiplier IC, such as the AD633. We've taught this classic shield a new trick: a realtime voice changer! Make sure the loudspeaker is pointing away from the microphone. That has the effect of overriding the modulation from IC2 and forcing the analog switch to remain closed. That’s done with 1% resistors R4 and R5. If you're a user of digital editing software Audacity, you already know you can do a ton of cool things. I’ve been a fan ever since. This circuit has various voice effects like transposing voice (higher or lower) ,amplifying voice and robot voice . In a number of situations we can manage to understand the occurrence of an individual in a group or in a special event simply by hearing to his or her voice, without even observing the individual. Let’s look at a few techniques (there are more than these). What else is there? The complete assembly runs from a 9V battery (B1). It would be tricky to debug the point of failure among all the possibilities. The frequency of the latter, which is about 512Khz, would depend on R2.After digitized voice signal is stored in a static RAM (SRAM), also regulated by the time base generator, a control circuit pulls info from the RAM and transferred to a latching register. One aspect of voice that contributes to its spectrum is dynamic range: As we speak, our voice gets louder and softer. Other ICs The Q output of IC2 is the control signal for the analog switch, so it’s the “carrier” that modulates the audio by turning the switch on and off. Using an oscilloscope to actually look at the voice signal from my talking Dalek toy, I saw the typical double sideband suppressed carrier (DSB-SC) wave form produced by a balanced modulator. Other companies make similar devices. ElectroBOOM Recommended for you. I this video, rock band 30 seconds to Mars is made to sound like Avril Lavigne. Resonance DSB-SC is basically an AM signal, but without the carrier. Voice modulator circuit. 5% coupon applied at checkout Save 5% with coupon. The current through the diode (Id) is controlled by the amplitude of the output, and rd = k / Id. Parts : P1_____10K Log. Integrated CircuitsModulator voice IC1- HT8950A, Transducers MIC1- electret microphone, miniature. Specifications. Balanced modulators are used in RF work to generate and detect signals. Referring to Figure 2, if point X is positive with respect to point Y, diodes D1 and D2 conduct and connect points A to A’ and B to B’, thus allowing the input to flow to the output. So, YOU can choose how you want to read your issues! There is also two special variation effects namely Vibrato mode and Robot mode. If it doesn’t go away, look for shorted traces. Verify that the LED is lit. Some interesting effects are produced by inserting a resonant peak into the middle of the audio spectrum. Voice This is what is done at a mixing desk in a recording studio, where the term “mixing” refers to  a linear process of addition. The audio is multiplied by the carrier input. Likewise, each section has a separate connection to ground. For example, four spoken words might look something like Figure SB1. The voice changer circuit 36 is illustrated in detail in FIG. If it’s low or zero, there’s a problem. Change your voice and add effects such as pitch or echo in real-time as you talk into the microphone on your Windows PC. You could answer that each person’s voice has a distinctive pattern of qualities that we can hear. The first function along with the two converts your voice with more tremulous while the second has impact on it simulating a robot kind of voice. The Wave Shield has long been a staple among makers' Halloween projects. The LEDs light up when the battery is connected. Voice changer 22 includes a power source 42 which may be, for example, a 9-volt battery connected to the voice changer circuit 36 by on-off switch 44 and a lamp 46. The PCB (DLKV) is double sided and measures 2.5 by 3.2 inches. Sometimes I’ll keep a chip such as an op-amp in a socket so that I can swap in various types to see if there is any difference in performance. Figure 2 shows a classic four-diode ring modulator. For the uninitiated, Dr. Who is a sci-fi show produced by the BBC. But if point Y is positive with respect to point X, diodes D3 and D4 conduct and connect points A to B’ and B to A’. Since an electret mic produces a relatively large signal, IC4 is configured for unity gain. Since RD « RL, we have Vout » (RD / RS) x Vin » zero. This circuit effectively multiplies the voice signal by a unipolar square wave (switches between +I and 0): half the time Vout » Vin; and half the time Vout » 0. Terms & Conditions | But how would you quantify those qualities so that they could be measured objectively? DSB-SC is basically an AM signal, but without the carrier. Skype Voice Changer is a cute program for Skype users. The amplifier is set to a fixed gain. It relies on our old friend, the diode. Some readers prefer a paper copy they can hold in their hands or keep on their bench. This circuit design project is very simple and require few external electronic parts . Description. Pitch buttons make your voice sound lower or higher. Figure 1 shows a simplified version. R6 references the input of IC4 to the audio ground. The VU circuit (see photos) comes from this page I found on the internet. Changing a Voice Obviously, the signal in Figure SB1 is some complicated function of time. Of course, I had to get one. The voice signal from the microphone is coupled via C5 to buffer op-amp IC4. Electrocution in Water - Duration: 6:41. This board has two test points. Get your team aligned with all the tools you need on one secure, reliable video platform. This circuit has uses 2 IC chips, LM386N op-amp, and an HT8950, voice modulator chip. As you decrease negative feedback, the effects become greater. Do you think you would be interested to change the timbre of a person's voice at will and make it tend to be unique to other people? On the other hand under both the outputs the voice is fed to the IC by way of a typical electret microphone and the dimensioned output is reproduced by way of a dynamic speaker. But if that’s not you, then get the Online Only Edition and save a few trees and some cash. Need to brush up on your electronics principles? Take a bare piece of solid wire, make a 90° bend in both ends, and solder it to the holes so that the wire is spaced about 1/4 inch above the board. I used a 741 for IC4 because they’re inexpensive, easily obtainable, and I had a bunch. Voxal is free voice changer software for Windows designed to enhance any game or application that uses a microphone. With the diode switches closed, a very low resistance (RD) is in parallel with RL. Anyone who has ever watched Doctor Who will be familiar with the peculiarly distorted voice of the Dalek. Supply input : 6 VDC @ 200 mA; Output : Speaker, 8 Ω / 0.5 W; Audio amplifier type LM386 with volume control preset; Jumper selectable tone frequency for encoding sound You would replace JP with a switch. The output of the voice changer goes to the speaker on the chest. The Voice Changer PCB is available in the Nuts & Volts webstore. Any hum on the DC from the AC mains will be amplified. Before applying power, clean the board with rubbing alcohol and an old tooth brush and give it a careful visual inspection. With the jumper out, R9 has no effect since IC2 and IC5 are CMOS chips. The lamp indicates that the voice changer 22 is on. Because of slight differences in our vocal systems, when I say the word “tomato” it will have a slightly different spectrum than when you say “tomato.” Our brains can distinguish those differences. The resistor R6 plays the role of a pull-down of the D / A HT8950 internal current mode and trimmer R9 as master volume control system. This signal can be acquired on the AUDIO output (pin 12).Depending on the speed with which the SRAM data to the D / A are supplied, the original signal is reproduced with or without offset frequency spectrum. Security Electronics Systems And Circuits, Restoration of a Vintage Telefunken Jubilate 5161W AM/SW/FM Receiver, Build an AM Transmitter for Use with Antique Radios, An Introduction to the Parallax Propeller 2, A Real-Time Operating System for the Arduino, REVIEW: Dr. Duino’s Starter Kit for the Arduino Uno, 25 kΩ, Single-Turn, PCB-Mounted Potentiometer, 0.1 µF, Monolithic Ceramic for Bypass (decoupling), Terminal Block, PCB Mounted, Two Contacts, RadioShack part 276-1388 (also Molex 39890-0302 or equivalent on 0.2 inch spacing), Shorted copper traces (especially IC pads), IC socket lead bent under and not in hole, Missing components (especially monolithic caps). Four 1/4” corner holes provide a way to mount the board. The amount and duration of the echo can be adjusted. However, if multiplying by a square wave will do the job, why not use an analog switch IC? The modulated audio output is capacitively connected to a loud speaker via terminal block TB2, and easily drives an 8W speaker. So, in a voice-over circuit, there are two inputs, one has a higher priority than the other one. Then remove the jumper as you continue to speak and verify that your voice is modulated. Nov 26, 2015 - This voice changer circuit electronic project is designed using the RTS0072B. Resistor R9 is required to isolate the output of IC2 when the jumper is in. (In real life, some carrier will leak through; but with good design, you could get 60 dB of carrier suppression.). In accordance with a voice modulator technology from HOLTEK, this voice changer chip digitally processes the fed voice signal all the time. Features a built-in microphone and power amplifier with volume control. Add a vibrato effect, use the 'pitch'-buttons and make your voice sound lower or higher. Gold $29.68 $ 29. Get it as soon as Fri, Jan 15. Selected questions from past Q&A columns. With respect to audio ground, actual ground looks like a negative voltage. Dalek & Cyberman Voice Changer With Arduino Uno: After building a full size Dalek in 2012, I wanted to make it talk and I didn't have the budget for the high end audio equipment that some people use and wanted to see if it would be possible to create a simple, low-cost voice changer using an Ardui… I understand resistors and capacitors are needed to minimise the current to the circuit, however i am unsure why each of the components are there. R3 connects the five volt bias to the microphone’s built-in amplifier (see symbol in Figure 5) and also sets its gain. 68. Capacitor C11 decouples audio from the power rail. You can use a better op-amp (e.g., LF411) if you have them. A very simple voice changer electronic circuit project can be designed using the RTS0072B single chip CMOS LSI designed for voice changer, which can transpose or distort one voice into another voice by encoding the input audio signals in normal speed and transmit the output audio signals with unusual speed. Holtek HT8950 IC S1,..., S4-push-button switches Miniature NAJ1- type connector for 9V battery snap. The planned digital voice changer circuit is merely created to make this happen for you, and quite much more. With the jumper in place, the voice changing effect is disabled and the board performs as a plain audio amplifier. RTS0072B voice changer circuit must be powered from a DC power supply circuit that will provide a fixed output voltage between 3 and 5 volts . Using band-pass filters, the audio spectrum can be divided into several subranges. The quality tone of every single individuals voice is especially one of a kind in all conditions. With the jumper in, set volume to minimum, plug an electret mic into J1, attach a loudspeaker (or headphones), and attach 12 volts to TB1. A balanced modulator can be built in several ways. How frequently we get a phone call and just by simply listening our interlocutor has the ability to realize right away who it is on the other side. The 1496 requires +12V, -8V, a fist full of resistors and capacitors, and a carefully adjusted trimpot. The sampling signal generator delivers a time base, in turn regulated by an oscillator. All you need to add is a speaker of 4 to 32Ohm (max. C7 is required since the input of IC6, an LM380, is referenced to actual ground. I found different values for the frequency of the sine wave in different sources; the range was 30 Hz to 100 Hz. 2. C11 is there to remove audio; it’s not big enough to remove AC mains hum. We can’t emphasize this one enough: work through the original Wave Shield tutorial before moving on to the voice changer! Notify me via e-mail if anyone answers my comment. If we never varied the loudness of our voice, it would sound mechanical. In effect, the input is multiplied by -1 and is inverted. This is done with pitch control, or autotune, and will like you modify the voice by a number of octaves. It creates a complete home audio workstation that provides all the tools you need to create your own great recordings. There is a hole at each end of the strip. Fuzz Figure SB3 shows a simple limiter circuit. Each of the component sine waves would have a specific amplitude and frequency. I didn’t want to just build a circuit with three audio transformers. This chip is found in several voice changer kits currently being sold. Which brings us back to spectrum. It can flexibly alternate your voice pitch between male and female in the Skype call, and send funny sound emotions to your contacts. Diode D1 protects against reverse polarity. Microphone jack J1, volume control R7, and jumper JP are all board-mounted. To use an unregulated wall-mount supply, you could use the circuit described in my upcoming article on switching regulators. (When used in a detector, it’s usually called a mixer.) She walks you through the instructions, reviewing symbols, components, and concepts learned in previous episodes. This voice changer circuit diagram electronic project is designed using the RTS0072B single chip CMOS LSI designed for voice changer applications , which can transpose or distort one voice into another voice by encoding the input audio signals in normal speed and transmit the output audio signals with unusual speed. But in a voice changer, a little distortion might be a good thing. If Id becomes, say, 10 mA then rd becomes 2.6 Ω and the diode switch is closed. That is accomplished by sampling the input audio signals into digital Mixing You can set the frequency that sounds best to you with C1. Copyright Statement, Virtual Instruments Improve Electronic Experimentation, DIY Biotech: Harnessing Bacteria for Fermentation, RADAR And Electronic Warfare Fundamentals, Understanding Digital Buffer, Gate And Logic IC Circuits, Smiley's Workshop: AVR C Programming Workshop, Smiley's Workshop: Serial Communications Between An Arduino And A PC. modification of a voice changer toy. I am looking for a pitch change and vibration distortion options. In this episode, Karen assembles as Velleman MK171 Voice Changer kit. Princeton Technology makes the PT2399 “echo audio processor” IC which (as you might guess) adds echo to an audio signal. TP2 allows you to look at the signal going into the power-amp.