An exploration of your house in close-up
This month we look at computer & TV screens
and the 'hi-fi' system

Welcome to this new monthly series which encourages you to explore in close-up the everyday things around your home, garden and garage.

What do you need? - each subject covered in this series will have an icon to show what you will need to study an object.

can be viewed with a 10X hand lens or similar magnifying glass.

use a low power stereo microscope 10X-40X for a clearer look

requires a compound microscope with magnifications 30X up to 200X

Who is the series designed for? We've tried to make it of interest to both the novice and more experienced microscopist. Each topic will have a brief description with images to illustrate the fascinating things you can find to look at. But there will be a click here prompt for many topics which will provide more background information and suggestions for further study.

This can be an exploratory journey together, because the author admits he rarely looks at everyday things under a microscope .... so why not join me to explore the fascinating world in close-up around your home!

Each month we will cover one particular theme and will include tours around each room to look at the TV, computer, hi-fi as well as food, clothes, printing and any plants or insects found along the way. It's amazing how household items we all take for granted become fascinating when examined more closely.

Each image shows a scale bar in fractions of a millimetre to make it easier to judge the scale at which an image is viewed.

This month we look at computer & TV screens and the 'hi-fi' system

Computer monitor and TV screen
So, where do we start? What better place than the computer monitor screen you are probably looking at. Go on take a closer look, if you get really close you should see the coarse detail of the phosphor stripes (or dots) applied to the back of the screen which generates the colours when electrons strike them. But to really appreciate how the colours are generated look at this red, blue and green text with a 10X lens to see how the coloured stripes change in relative intensity as you move from the coloured text to the white background.

The image on the right is my best attempt to photograph my monitor screen with a 35mm camera using macro facilities. But because most monitors have a fine 'dot pitch' of 0.26-0.28mm it doesn't show the phosphor detail well.

To really understand how the phosphor builds up colours, have a look at a TV screen with the 10X lens (turn the TV on but turn down the brightness to reduce glare). An image of the screen is shown on the left. It is immediately apparent even with the naked eye that the phosphor stripes are much coarser.

Compact discs and LP records - 'looking' at analogue and digital information
How many times have you played a music CD or loaded one on your computer CD drive, but have you ever looked at the digital information? You can actually see the digital information on a CD disc with a microscope. The digital information is encoded on the disc in the form of a spiral track of pits which are 'read' by the laser which scans the disc. The pits can be seen under a 20X objective on a compound microscope if you shine an intense beam of light on the CD below the objective. They are just visible in the image right but will be easier to see if you try looking at them yourself with the 20X objective and 10X eyepiece.

Records - remember them ?
If you have an LP or 'singles' record, try viewing the record under a stereo microscope to see how the musical information is stored in an analogue form rather than the digital form on a CD. You will need an intense source of light to reflect light off the record to see the record grooves. Try shining the light at different angles to get the best effect. If like me, you were able to find a transparent record, you could also try using transmitted light. The image left below is taken by reflected light and the one on the right by transmitted light.

Unlike the digital information on a CD, you can gain some idea of the type of music being played by looking at the analogue information. In louder passages of music the left and right walls of the groove wave side to side more intensely than on a quieter track, and the 'frequency' of the wave provides an indication of whether a predominantly low or high note is being played.

Record stylus
While on the subject of LP records, it is also worth looking at the record stylus or 'needle'. In most modern record players the stylus is part of a module that is designed to be safely removed from the cartridge attached to the playing arm. (If you're a young reader, check with your parents about removing the stylus module as they are easy to damage!)

Use either the 10X hand lens or stereo microscope to study the structure of the stylus. The one on the right above is from a relatively cheap cartridge because the needle is large and has a simple cone shape. Compare this with the more expensive stylus shown on the left taken at the same magnification. The needle is smaller and more precisely made, and is probably made from industrial diamond. Notice that it is elliptical at the point, ie it is wider viewed from behind than when viewed from the side. The long axis of the ellipse sits at right angles to the direction of the groove.

Cassette player record/playback head
The record/playback head in a cassette recorder is usually difficult to get a good look at because it is hard to access and should not be removed or touched with a metal object. Although shining a torch on the playback head while the cassette loader is open should give you a reasonable view.

My brother was replacing the cassette head on his cassette player so I took the opportunity to have a closer look at it. I was also able to compare a high quality and lower quality cassette head to see if there were noticeable differences. Compare these two shown left and right, which are at the same magnification and are views of the part of the head that contacts the tape as it moves past. Which one do you think is the higher quality component.

Important note to younger readers
The author is not encouraging you to dismantle electrical or other equipment in this series as it is potentially dangerous and could also damage the equipment. But if something is being repaired or being taken apart by experienced people why not ask if it is safe to take a closer look and also ask how it works.

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Comments to the author Dave Walker welcomed.

Disclaimer: all the information in this series is given in good faith. However, no responsibility is accepted for damage to property or injury to persons as a result of readers investigating the subjects described. It is up to the reader to judge whether the subjects can be safely viewed in their own home. Younger readers should consult their parents or teacher as appropriate before examining either their own or somebody else's property.

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