laser receiver project, is there anyone who would help put together for fee please?

[jarvouk]

See the main problem I have is that most of the words you just typed I don't understand lol I get the parallel part where I could just adjust the dial thing to tweak the sensitivity to compensate for all the trickling sensors.

I looked at that circuit and it's probably the most basic thing but it's like another language to me.

My Arduino kit arrived though so hopefully in a while some of this will start to sink in! :0)

 

[DrG]

You can make a working target with your Arduino experimenter kit. I see from the pictures that it includes two CdS light-dependent resistors.

Those will change their resistance with light. Hopefully, you have, or will invest in, a volt-ohm meter as it will be helpful.

If you read about what a resistor divider is (see link in my previous post or a bazzilion other links), you can set this up on the breadboard...

The Arduino analog input pin (A0) is capable of reading the voltage at the junction of the divider. It will return a number between 1023 and 0, depending upon the voltage at that pin. The voltage will depend on the resistor values and the resistor value for the CdS LDR will change significantly when it is hit by your laser pointer. The resistance of R1, which is fixed, will not change. So, by monitoring the value of the analog input, you can tell when the target has been hit and when that happens, you can sound a buzzer (you have one of those in the kit as well).

You could also incorporate a potentiometer, which is a variable resistor, in place of, or in addition to, R1 (you have one 10K ohm potentiometer in the kit) - you turn the knob and the resistance changes. This might come in handy when you think about changing ambient light levels.

There is much that I am leaving out, but that is the basic idea, and yes, you could put several CdS cells on the bottom and increase the target area.

So, you have lots of fun experiments to do.

The approach that I am describing is different than using a comparator IC, as described by rjenkinsgb, but once you set up the scheme above and learn how to do some coding, and exploring, it should help you with using comparators ICs, if you wanted to go in that direction.

Hope this helps.

 

[jarvouk]

That's really kind of you thanks! I will persist and get stuck into this Arduino cheers

 

[jarvouk]

Hi I'm not sure if anyone has time or the willpower to respond but I did hire someone to help me design a circuit and list the parts needed.

I am not entirely sure if it's correct as I have very limited knowledge of electronics. If someone could kindly take a look at these and see if it makes sense I would appreciate it!

Just to reiterate I wanted a simple circuit that when a laser pointer hits a cluster of target LDRs the solenoid would trigger and strike a bell. I wanted it to run off a 12v battery. I think the author of the circuit here confused bell with solenoid but I'm guessing it will work the same.

Edit: I can't open the docx file on my mobile to upload it but it's just a parts list

 

[dr pepper]

Yes it kinda makes sense, its a little clunky but it'll probably work.
The design triggers a relay, and then the relays controls the bell, one important addition would be to connect a diode across the relay coil, anode to pin 1 and cathode (stripe end) to pin2.

 

[jarvouk]

The bell was I think supposed to be the solenoid. I hope that works the same way just firing instantaneously and resetting again after.

Thanks so much for taking a look at it for me I'll go ahead and order the parts and see what happens

What would the purpose of the diode be across the relay coil?

 

[dr pepper]

The diode across the coil absorbs the voltage spike that the coil creates when its switched off.
A 1n4001 will be Ok.

 

[jarvouk]

Nice ok that's really cool thanks. I think I can see where it goes I might try drawing it on this weekend and post a picture to see if it's correct if that's ok.

I saw that other conversation link you sent thanks I'm at work at the moment but will definitely check it out cheers!