1970s AVO Pocket Light Meter Model 3 LM3 In Original Green Leather Case

This lovely little piece of vintage tech is a 1970s AVO Pocket Light Meter Model 3 LM3 In Original Green Leather Case. It also comes with its original operating instructions!

Approximate Size (WHD):  5.6 x 7 x 2.6 cm

It would have been used by Lighting Engineers to measure the lighting source in different working environments e.g. office, classroom, factory floor e.t.c. It has a table on the back of the instrument, and in the operating booklet, giving a selected set of recommended illumination values for different types of work/working environment.  

It has two ranges of sensitivity, and is calibrated in both foot-candles (lumens per square feet) and lux units. You press the switch on the side to move from the lower (x1) to higher (x5 measuring up to 2500 lux) sensitivity range. For most lighting conditions, the light meter would be used in the lower range (the small aperture beneath the scale becomes white with x1 written in the middle: 0-500 lux).

1 lux = 0.093 lumen/ SQ FT )or 1 Ft.C

It is in very good working and cosmetic condition: with some superficial scuffs. I'm not sure how accurate it is!

Summary 

• AVO Light Meter LM3:  Avo Limited, Archcliffe Road, Dover, Kent. (Part of the Thorn Measurement Control and Automation Division). Manufactured by Avro Limited, Avocet House, London SW1
• Meter Type: Photo electric cell
• Body: Grey Metal with White face and black scale.
• British Patent No. 640117 
• Made in England 

A wonderful little scientific instrument, which can still be used today. There is even one in the collection at the Science Museum!

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