Make laser gate to see fast objects

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ericgibbs said:
hi Simon,
Mirrors are a bad idea.

A lens at the emitter and detector should give a beam with a sufficient angle to cover the balls path.
Click to expand...

Why do you say the mirror is a bad idea?

How would the lense at the emitter and detector solve the problem of the ball jumping over the beam?
 
Hero999 said:
Why do you say the mirror is a bad idea?

How would the lense at the emitter and detector solve the problem of the ball jumping over the beam?
Click to expand...

Perhaps if you posted a sketch on how you see these mirrors are arranged, I will discuss it with you.

If the beam is set wide enough to cover the expected limits of the balls path thru the beam then how would it jump over the beam.?
 
But if the beam is larger than the ball then surely the ball won't completely obscure the beam?

Of course it would reduce the intensity slightly but will it be enough to detect?

If it clips the side of the beam it might not be enough to trigger it, so doesn't that mean the beam needs to be larger than the area you want to monitor?

Here's a sketch of my mirror idea.

I've not done this before so you could be right, it might be a bad idea.
 

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I can see where you are coming from with the mirrors, but I would think the alignment and quality of the mirrors would have to be first class.

Also the reflected angle would have to be less than the ball diameter in order to ensure that the ball didnt pass thru a gap.

We would have to know the working width between the two mirrors.
 
since jumping over the beam is not a problem then I see no use for any of the suggestions to fix that problem thanks though.

For the modulated and pulsed emitter I might need to ask for some other explanation. Sorry but I am still quite a nub and google wont help me to figure out what they do. I would guess that it means that the transmitter sends the signal in waves, but it allready does that, I saw it on my oscillator.
 
Umm... Just a suggestion here... The sun does NOT put out DC frequencies... The frequency component, is quiet active in the low frequency range. There is little to nothing you can do if the receiver itself will be directly in sunlight, between the massive DC offset of the sheer power of the light it's receiver compared to the transmitter and the frequency components that are present you'll be lucky to sense anything.
Acoustic methods?
 
Even though pulsed emission is the way to go here(as like a TV remote control), I'd find the LDR option is also practical as you told it works well at increased gain conf.
 
transistor495 said:
Even though pulsed emission is the way to go here(as like a TV remote control), I'd find the LDR option is also practical as you told it works well at increased gain conf.
View attachment 41637
Click to expand...

ah thanks Ill try look more into that. I have to figure out how to make the LDR give me 8v in shade and around 11,5v in direct sunlight. I do have some ideas for that.
 
Last week I told a guy to funnel the passageway down and let the ball run over a microswitch. If you can't narrow the passage, 8 inches is probably narrow enough to make a mechanical sensor.
 
If going with the LDR you are aware that it won't work when its cloudy.
Look at using a voltage comparator circuit for your LDR (cDs cell).
very simple to build.
 

Agreed, surely the bright light from the sun will saturate the receiver so it won't be able to detect anything?
 
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