Telephone voice changer - DIY project

Change your voice over the phone in real time using a computer or digital processor. 

 

This black box allows routing effects through your phone system

This project converts an old desktop telephone into a versatile audio mixing station that lets you route your telephone calls through an effects processor in order to create a state of the art voice changer. By using a real time computer voice filter or a professional quality effect box, you can change your voice in ways that will make you sound like a completely different person. You can make a man sound like a woman, or a girl sound like a man, or a man sound like an elderly lady, or any possible combination imaginable with results that will fool anyone.

Unlike those "spy toy" voice changers that make you sound like a funny cartoon, a real vocal effects unit or computer vocal filter will alter a voice in a perfectly convincing manner, allowing fine control over both the formant (gender) and the pitch of your voice. Sure, you can have a lot of fun with evil and chipmunk voices as well, but if you really want to mask your voice identity in a convincing manner then this useful device will allow you to connect any microphone compatible audio processing unit into your phone so you can alter your voice in real time. 

There are many extremely powerful audio processing programs available for a computer that allow a person to alter his or her voice by talking into a microphone. Many of them are inexpensive or even free. Music stores also offer digital effect boxes that are designed for vocal processing, and these have the same functionality as the computer programs, but do their processing in a dedicated DSP (digital signal processor). I will be using both the computer software voice changer as well as the "effect box" version of the vocal processor to show how each one can be connected to the phone system using this project.

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Motion Activated Camera

A motion activation system that will control the digital camera shutter release button.

This rig will take a photo anytime it senses motion or heat changes

This project uses a heat sensing motion detector to trigger the shutter release button on a hacked digital camera so that high resolution images can be captured anytime a person or animal crosses in front of the motion sensing zone. By hacking into an old motion activated floodlight, the cost is kept to a minimal and based on a pre-existing system that is known to work well. This project converts the motion sensor for DC battery operation, allowing it to become portable and safe from high voltages.

This project also makes use of a circuit from a previous project called "Camera Trigger Hack", which is a pair of relays and drivers fed into the shutter release switch on a digital camera in order to mimic the original functionality of the switch. You could probably feed the output from this circuit directly into the camera shutter switch, but to be safe, the relay adds a level of isolation from the camera circuit board. Some cameras also have an external remote control jack. This could also be used.

Figure 1 - Any common outdoor motion sensor light can be used for this project

Motion sensing lights like the one shown in Figure 1 use a special heat sensor to detect movement of warm bodied creatures. This sensor detects the body heat of the subject as it passes across a pair of small sensing elements inside the heat sensor. This heat sensor is also known as a PIR (Passive InfraRed) sensor and is the magic behind every one of those inexpensive outdoor security lights as well as most indoor motion sensing units. 

Because these devices are mass manufactured, they are easy to find as surplus or even new for very low cost. Many security lights are tossed out when the plastic degrades or when the relay that controls the AC lights fail, so you can probably salvage the needed parts even from one that is deemed to be non functional. 

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Sound Activated Camera - DIY electronics project

A sound activation circuit that will control the digital camera shutter release button.

Figure 1 - This is the relay interface that controls the camera shutter switch

The small board shown in the left of Figure 1 is a previous project called "Camera Trigger Hack", and it allows any electronic device to issue a focus and shoot command to the camera. I call this a hack because it requires removal of the original switch from the camera in order to hack into the two functions that control the focus and shoot signals on the cameras circuit board.

You "may" be able to build this project without the previous project as long as your camera board will accept the 5 volt digital signals from the 74121 one-shot into the cameras board, but to be safe, this previous project adds a level of safety to ensure your camera will not be damaged by any external device or voltages.

The small circuit board shown in the right of Figure 1 is the board that will be presented here, and it consists of a small microphone, an op-amp preamplifier (LM358), and a digital one-shot switch (74121), which controls the pulse time to the relay board that will trigger the shutter release switch. The one-shot is needed as the camera expects the shutter release to be pressed down by a human, and the pulses sent from the microphone preamplifier will be much too short to be taken seriously by the camera. The one-shot takes this millisecond input pulse and then sends out a digital pulse for a duration that is long enough for the camera to respond.

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Repeating Camera Timer - DIY electronics project

An adjustable timer that will continually focus and shoot images on a digital camera.   

      

This system will focus and shoot a photo at some repeating interval This project will extend the "Hacked Camera Trigger" project, allowing a timer to control both the focus and shutter release functions on a digital camera at an adjustable rate. This method of repeating time delayed image taking is also referred to as a "time lapse photography", and can be used to speed up time by piecing together hundreds of photos taken over the span of hours or even days. By first focusing the camera before the shot, the camera will be able to acquire moving targets with far fewer missed or blurry exposures. In this project, a timer feeds a 10 stage counter, allowing up to 10 individual control points, although only two are needed in order to control the camera relay interface. By using the other eight digital output pins on the decade counter, several more cameras can be controlled, or more relays can be added to allow the controlling of various other electrical devices such as solenoids, alarms, lights, or even AC operated appliances. The rate of photo taking can be controlled by a variable resistor, and by altering the value of the timer capacitor, rates of several photos per second all the way down to single photos every hour can be set. This project assumes that you have previously built the "Hacked Camera Trigger" project, although you could certainly interface it to some other hardware as well. Figure 1 - This is the relay interface that controls the camera shutter switch The small board shown in Figure 1 is a previous project called "Camera Trigger Hack", and it allows any electronic device to issue a focus and shoot command to the camera. I call this a hack because it requires removal of the original switch from the camera in order to hack into the two functions that control the focus and shoot signals on the cameras circuit board. You "may" be able to build this project without the previous project as long as your camera board will accept the 5 volt digital signals from the 4017 decade counter into the cameras board, but to be safe, this previous project adds a level of safety to ensure your camera will not be damaged by any external device or voltages.

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