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Light Meter

March 4, 2012

Light MeterI was given a Yashica Mat-124G camera and you cannot get batteries for the light meter, so I decided to make one.

I already had the analog meter and the small box, so the two were a natural fit.

I also used Adobe Illustrator to make a new paper template and scale for the meter.

This needs some work and I realize this is not actual lux levels.  The trick here is to come up with a scale useful to the camera I will be using it with.

The sketch I used is fairly simple.  Basically I’m reading 10 values from the photocell and getting an average.  This gives me a value from 0 – 1024.  Then I map the values from 0 to 255 and write it to the meter.  I am now the proud owner of probably the world’s biggest and simplest light meter.

Here are the parts I used:

1. Proto board from Adafruit

2. 1k resistor, 10k resistor 10k & 100k resistor

3. Analog meter from Adafruit.

3. Battery pack with on/off switch

4. Photo cell

5. Wooden box (old cigar boxes work great.)

6. Wire and heat shrink

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2 comments

  1. [...] Light Meter @ Electric Projects. I was given a Yashica Mat-124G camera and you cannot get batteries for the light meter, so I decided to make one. I already had the analog meter and the small box, so the two were a natural fit. I also used Adobe Illustrator to make a new paper template and scale for the meter. This needs some work and I realize this is not actual lux levels.  The trick here is to come up with a scale useful to the camera I will be using it with. [...]


  2. [...] the previous post about the light meter for full details Share this:FacebookTwitterRedditStumbleUponLike this:LikeBe the first to like this [...]



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