Make laser gate to see fast objects

Hello Electro tech

I am making something for a miniature golf to register the ball passing. It should turn on blinking lights for few seconds.
The blinking lights are working and the gate to register the ball is also working BUT.. I am using infared and they are at the absolute maximum length from each others using kamera lenses in front of the infrareds etc etc I done everything I can and it works when there is no sun. The sun interrupt the signal.
Since I worked so hard with these stupid infared I wanted to know if I could do it easier with some kinda lasers? It should just give me a signal when the ball pass through. Take in mind that the ball is small and it runs fast. Anyone have any idea how I could make this?

AC coupling will block the DC of the sun. it does not matter what you do if your sensor is non directional though.

drive your emitter with an oscillator and put a capacitor in the receiver analog electronics. a tube on the receiving end will make sure the receiver is in the shade and might be enough for your system to work as it stands since you say it is working when the sun is not out.

while you do not need a laser it could make it easier if you are looking at long distances and certainly a visible pointer for a source makes it easy to set up

dan

Ubergeek63 said:

AC coupling will block the DC of the sun. it does not matter what you do if your sensor is non directional though.

drive your emitter with an oscillator and put a capacitor in the receiver analog electronics. a tube on the receiving end will make sure the receiver is in the shade and might be enough for your system to work as it stands since you say it is working when the sun is not out.

while you do not need a laser it could make it easier if you are looking at long distances and certainly a visible pointer for a source makes it easy to set up

dan

Click to expand...

The transmitter and receiver are allready at maximum length from each others and they are both being protected with a tube for as less sun as possible. The sun that is coming in now cannot be reduced in any way. I am looking for a new way to build this kinda system or some way to improve my current one.
Without sun it works perfectly, in sun it wont recieve a powerful enough signal. I can gain voltage on my transmitter side and make it recieve a working signal in sunlight, but when it then gets dark the signal is too powerful to "see" the ball passing. I could actually make it work in sun but then it wont work in shade. There must be some kinda circuit that is able to do this and register fast moving objects.

Another solution I have thought about, was to add an LDR in series with transmitter circuit. The LDR will be less resistant in sunlight tus giving higher volt to the transmitter during sunlight. I just think this is a very weird solution, especially because we have had a company making a working solution years ago, but it cost alot of money and now I study my self (1 year only though).

I dont quite understand what you want me to do, but ofcourse it aint easy while I cant provide any schematic for the circuit.

As he said, modulate the IR, and AC couple the receiver - you then need to detect the lack of modulation frequency, not just a lack of signal.

You need to pulse the emitter. Most if not all tv remotes use I think 30khz pulse.
here is a IR transmitter
https://www.electro-tech-online.com/custompdfs/2010/04/tsop382.pdf
do a search about IR remote control.

Try adding a dark red filter in front of the detector to block most of the ambient light.

crutschow said:

Try adding a dark red filter in front of the detector to block most of the ambient light.

Click to expand...

that was easy to try, Ill start with that

MrDEB said:

You need to pulse the emitter. Most if not all tv remotes use I think 30khz pulse.
here is a IR transmitter
https://www.electro-tech-online.com/custompdfs/2010/04/tsop382-1.pdf
do a search about IR remote control.

Click to expand...

do you have any idea if these are fast enough to register a ball? Miniature golf. It goes quite fast

I am using similar in an air cannon I am building. A chronograph to measure how fast projectile is traveling.
Aproximatly 500fps+
Don't think a golf ball will travel that fast.

SimonTHK said:

do you have any idea if these are fast enough to register a ball? Miniature golf. It goes quite fast

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A golf ball typically leaves the tee at perhaps 70m/s. A 30kHz signal has a period of 33.3µs during which time the ball travels 0.23cm. This give you 18 cycles of the 30kHz for a typical 4.27cm golf ball to move past a single point. Thus, even for a golf ball hit off a tee, you should be able to detect it with a 30kHz modulated signal.

Have I missed something here?

Over what area do you need to detect the ball?

If it's fairly large, how are you going to ensure the golf ball interrupts the laser beam?

Hero999 said:

Over what area do you need to detect the ball?

If it's fairly large, how are you going to ensure the golf ball interrupts the laser beam?

Click to expand...

thats easy... i would be more worried with the ball bouncing over the beam

Ubergeek63 said:

thats easy...

Click to expand...

Is it? Really?

Ubergeek63 said:

thats easy... i would be more worried with the ball bouncing over the beam

Click to expand...

That's what I mean, if there's a single beam you can't be sure that the ball is going to interrupt it.

Hero999 said:

Over what area do you need to detect the ball?

If it's fairly large, how are you going to ensure the golf ball interrupts the laser beam?

Click to expand...

20cm wide. The transmitter and reciever are placed 20 cm from each other.
The ball is running up a hill before it reach the gate and that will make it quite unlikely to jump.

Take in mind that my circuit is perfectly working in shade not in sunlight. I could easily see on my oscilloscope that my signal recieved, was getting worse when sunlight reached the gate.

How about using two mirrors and angling the beam so it bounces off both mirrors zigzagging the area where the ball needs to be detected before hitting the sensor?

Hero999 said:

How about using two mirrors and angling the beam so it bounces off both mirrors zigzagging the area where the ball needs to be detected before hitting the sensor?

Click to expand...

would that fix the sun problem?

SimonTHK said:

would that fix the sun problem?

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hi Simon,
As Nigel has pointed out, the only sure way to 'reduce' ambient light effecting the detector is to use a modulated or pulsed emitter.
The emitter can be pulsed fast enough to ensure that if the ball breaks the beam it will be registered by the detector.

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.

ericgibbs said:

hi Simon,
As Nigel has pointed out, the only sure way to 'reduce' ambient light effecting the detector is to use a modulated or pulsed emitter.
The emitter can be pulsed fast enough to ensure that if the ball breaks the beam it will be registered by the detector.

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...

actually i said it first in msg #2 ... kinda difficult to beat out the first reply!

Ubergeek63 said:

actually i said it first in msg #2 ... kinda difficult to beat out the first reply!

Click to expand...

hi D,
Sorry about that.
I'll get it right next time.. I do try to get the Credits right.

I was temporarily blinded by the flash from that cracked multi mirrors suggestion.

Regards
Eric.