Audio Video Home


One area that I've been interested in for a long time is Audio and Visual devices, namely sound, video and photography.
This section covers mainly the accessories that I'll be building.

Visual
For a few years I've had the idea of doing Aerial Photography and Video, I've played with several thoughts on how to achieve this on a limited budget, we all know that you can hire a plane or helicopter to either doi the photography or filming, but not all of us can afford that price tag.

So starting from the top end of a budget, here are the options available:

Radio control plane or helicopter -
A plane may work for video, but a helicopter would be more stable for photos, development of image stabilisation in small lightweight cameras is good and getting better.

Helium 'Blimp' -
Apparently you can buy these, mostly for advertising your business, you tie them somewhere so it floats above for all to see for miles, one problem is that it moves around in the breeze, one way to overcome this would be to have 3 or 4 guy ropes so when the blimp floats, the ropes form a giant tripod, you then suspend a camera below with remote pan and tilt control.
I'll be adding the basic design, but don't think I'll be building it any time soon.

Tower -
Some form of lightweight easily erectable tower with the pan/tilt on top, the base of the tower would have to be substantial, or you must be able to add guy ropes, so the limitation would be someone's garden.

Camera Crane or Boom -
A camera crane is like a boom except that the crane is usually extendible in use, so is a bit more complex as weight needs to be continuously adjustable too.
The boom is simpler as it's length is fixed, even if you are able to add extensions.
I'll be posting several designs that I made in this part of the site.

Mini Manual boom -
Not so much for aerial photography of houses, but useful in the studio or even outside for model photography.
This is basically a camera boom, but the pan and tilt are manual, you would use it like a tripod to steady the camera, but it's infinitely adjustable on the go, no playing about with the tripod between shots.

Audio
This will mostly be covering audio used with the videos, so basically microphones and mixing, and covering a small amount of music

Types of microphone:

Ribbon -
I still have an old ribbon microphone, though the ribbon is missing, I hope to make a new ribbon and get it working again.
It works by having a ribbon of electrically conductive foil suspended between magnets, when the ribbon moves, it generates a very small voltage.

This is the ribbon mic I have, it's a bit dilapidated, but i hope to restore it a bit


Moving coil -
Very much like a speaker, a coils of wire suspended in a magnetic field, and fixed to a diaphragm, again this would generate a small voltage, you can actually use a small speaker, but sound quality will be a bit too bass'y to be of any good.

Carbon -
Usually found in telephones, it's a container of carbon particles, the diaphragm has a small needle amongst the carbon, a voltage via a resistor or inductor is fed to the diaphragm needle and to common, the output is the needle and common. it's audio modulated DC voltage


Electret -
More and more these are used in any equipment that needs a microphone, telephones, mobile phones, computers, webcams.
A voltage via a resistor is applied across the element, this powers a small electronic circuit inside the element, the audio output is the same terminals (in most cases) as where the voltage is applied, again this is audio modulated DC voltage.


Fibre Optic -
Yes you read that right.
The 'cable' from the microphone is actually just 2 fibres, one is from a light source, this shines on a mirror within the microphone that is connected to the diaphragm, and is reflected down the other fibre.
This is very useful in places where an electrical connection would be dangerous, an example would be high voltage areas, not because you would be close enough to get an arc, but more because the equipment at the other end could get loads of interference or cause other damage.

There are a few others, but i covered the most popular.

Also there are several 'patterns' of response, it really depends on whether you want the sound from all around to be captured (omni-directional), or just the one with the mic (uni-directional), or something more directional that can listen to one source at great distance.






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