• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

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

jarvouk

New Member
Hi there I have a relatively simple project to construct but have no experience myself, I don't think it would be that hard for someone who has had the time to educate themselves on the topic. I don't have a lot of free time to research it myself hence the fee attached.

I wanted to design a small circuit that triggers a solenoid when an IR laser is detected. Ideally I wanted several IR diodes grouped together (probably in parallel) to make a larger catchment area. I am guessing the solenoid could be a cheap 5v one as I only wanted it to instantaneously hit out and strike a small bell when activated and reset immediately.

The laser is a 5mw red laser like the pointers you get, I think the IR diode receivers would work but you would know a lot more about that than me.

If anyone is interested and thinks this is something they might be able to help with could you let me know please? I am in the UK.

Many thanks,

Si
 

rjenkinsgb

Well-Known Member
Most Helpful Member
I'd suggest a modification to the concept.
A simple on-off detector would be sensitive to bright light or reflected sunlight as well as a laser pointer.

Using a modulated beam gets around that; the light source is switched on and off at a high frequency (or even using a code, like a remote control) and the IR sensor ignores random brightness variations unless they switch at the right frequency or are sending the correct code.
 

jarvouk

New Member
Thanks for replying! I'm not adding or taking away from the source which would be a 5mw pointer, I understand it would be far more beneficial and effective as you suggest however it would be impractical to redesign the laser housing for my project. If I was building everything from the ground up it sounds like an excellent suggestion though.

The IR receiver could be housed in a shielded casing and recessed to protect it from extremes of light. I feel that would give it a suitable level of functionality and keep the circuit tinkering at purely the receiver end.

Does that make sense?
 

DrG

Active Member
I don’t have an interest in providing the service and I don’t live in the UK, but I did want to comment.

I would imagine that the price and problems of having something custom designed and built for you can become substantial and quickly.

While you think it is relatively simple, you also readily admit that you don’t know much about building the device, but will defer to those that have spent the time to learn about such matters and have the requisite skills and equipment. There is nothing wrong with that model and it is used all the time in areas like automotive repair. The difference is you and the person already have a good idea of what the desired outcome should be, i.e., a car that runs like it did before it broke.

I would suggest that one way forward would be to offer up a better level of detail about the specifications of the device and its purpose.

For example, from your description, I get the impression that you want something like this:
https://ads.midwayusa.com/product/1018119112?pid=279783

If the device is an audible laser target system, then there are many commercial products available and if they fit your specifications, they are probably going to be a lot cheaper. Additionally, there are probably a lot of DIY plans and write-ups of folks have built their own.

Finally, if you had some particular reason why the commercial products were not good enough, one might be able to modify them – again for less than designing and building one.

The better you provide the details of the “what” and the “what for”, the better your chances of getting what you want.
 

jarvouk

New Member
Thanks for commenting DrG. Yes that's the idea of a target system like the Laserlyte.

Surprisingly though there are not many similar products in what is a relatively niche market I guess, the Laserlyte targets are very highly priced which is why I was looking to make my own. I think theirs range from $100-$300 and importing from the US would not be desirable.

I have seen plans for laser tripwires on a lot of forums and as my design is very similar I had hoped it would not be a substantial step up in skill to rig in a solenoid instead of a buzzer. I just lack the knowledge to know which resistor, power supply to use.

If you think it's asking too much and probably too expensive and you are speaking from experience then I should probably scrap the idea for now then.
 

DrG

Active Member
If you think it's asking too much and probably too expensive and you are speaking from experience then I should probably scrap the idea for now then.
Not saying that necessarily, but it is something to keep in mind. Already more of the details are coming out and that is important. So, now we know what the device is for and approximately what kind of budget you have in mind (<$100?).

Do you have the "dry-fire laser cartridges" or ? Specifying the laser source would help - is any old laser pointer good or ?
EDITED: I see now that you did already specify the laser source as a "5mw pointer" in an earlier post.

I am seeing a lot of DIY and questions and comments online and at all different levels of sophistication.


Are you hooked on the solenoid striking a mechanical bell method, or are you just after audible feedback? A simple buzzer would be much cheaper.

Take a look at some of the onine videos and articles (like the 1st and 3rd link) and see if you find one where you are happy with the end product and start thinking about the simplest device for your purposes.

Once you know some more specifics about what you want and how much you want to pay, you can address the "should you scrap the idea for now".
 
Last edited:

jarvouk

New Member
Bloody hell that's embarrassing there are tons out there then? That's basically exactly what I was after haha

Really appreciate that I don't know what I have been researching then but obviously not very focused! Even that first link looks amazing. I will have a good look and then possibly get back to you but you guys have already been incredibly helpful thanks so much! :O)
 

rjenkinsgb

Well-Known Member
Most Helpful Member
For info, commercial "Laser tag" type systems do not actually use lasers in any functional way - the laser is for show and the working optics use infrared LEDs and IR receivers.

eg. Laserquest, q-zar, quasar or such - they all have a large tube in addition to the "barrel" and it's that which has the working optics, an infra-red LED plus a focussing lens to keep it to a narrow beam.


Some of those (quasar/q-zar, as an example) use normal infra-red remote control technology and can be reprogrammed via a generic programmable remote control!

If you don't need ultra-fine aiming accuracy, then you could possibly base it around something like these, with plastic lenses added for focussing:

 

jarvouk

New Member
Nice thanks for that info rgenkinsgb! I am looking for higher precision though so will stick with the laser.

That's fascinating how the ones you mentioned don't even use a laser though, had no idea!?
 

neophyl

New Member
Even the 'big' manufacturers of outdoor laser combat systems use infrared leds and lens units. I should know as I used to build them for BFS and I still do personally for hobby purposes.
As the detectors are less than 5mm square when using a laser the user has to be better than an olympic marksman to hit. Unless you are stationary target shooting or have a target that is literally covered in detectors which isnt practical then it becomes almost impossible to hit at any reasonable range. The logic is reversed, instead of shooting a very small projectile towards a large target you shoot a larger infrared beam towards a very small target. A decent infrared based system with proper optics and a reasonable sensor can work at 300+ metres easily. The main drawback of the IR based ones is that at powers required for outdoor use they are way over powered for indoors, any use hits everything inside as they light up the room. Which is why some fit indoor/outdoor switches to regulate the power.

The military Miles type system do use lasers but even they are defocused to reduce range and spread the beam angle. There is also the safety aspect of shining lasers towards people if they aren't using proper eye protection.

Every system I've seen uses some form of modulation on the beam, even if they aren't sending command codes. There's always a carrier and a 'hit' signal on top. Mainly as the common detectors are built to look for specific carrier frequencies (38khz and 56khz being the most common), The better ones also code data on top of that and then use error checking techniques like crc or even simple parity bits to reduce false positives.
 

jarvouk

New Member
Neophyl very interesting read thanks for that. I love the way they reversed the method large bullet small target what a great idea.

I will continue to research though and appreciate the sound advice here. A very useful forum you guys are oozing knowledge :)
 

jarvouk

New Member
Hi thanks so much for the help so far it has been really appreciated.

I managed to source an actual kit but I have to order a lot of them before they will post to the UK, this is not convenient for a prototype.

Would anyone be able to take a look at the circuit kit below and possibly take a guess at what components it contains please? It's asking a lot but would you be able to sketch out how you think the basic circuit would connect them up so I could try and build it here in the UK?


If you don't have time just ignore this post I am very greatful for the help so far. Cheers :)
 

rjenkinsgb

Well-Known Member
Most Helpful Member
I managed to source an actual kit
That is an incredibly crude circuit, no discrimination or lighting compensation - it will be switched by any form of illumination above the threshold set on the preset pot, not just a laser.

They will be virtually the same as Gary's circuit in the first post in this thread, but with the 100K and LDR swapped (and an adjustable preset in place of the 100K), but with more LEDs and to work on 9V.


There is a rather more sophisticated (but still working from any light) type on ebay at £24 for a pack of ten kits:

They have a relay that can control a separate light or sounder of some sort.
There are a lot of other light operated switch modules, but most turn on with no light - that has the option to to turn on when light is detected.

I'd put a section of plastic tube around the LDR with anything like that, so only light from the direction of the "shooter" can get to it, rather than all ambient light.
 

jarvouk

New Member
Wow that is great thanks I am at work right now but it's very kind of you to source these circuits. I can't wait to finish so I can start looking at them. Thanks again :)
 

jarvouk

New Member
I actually ordered an arduino starter kit tonight to try and educate myself on things a bit :)

Hey I was wondering, I came across this video here which shows a laser activating a 240v light.


Ideally what I wanted was for a laser to set off a 12v solenoid momentarily to hit a bell. A cluster of 7 sensors should give a larger target area.

Do you think the components in that video could be used in a similar way to achieve this?
 

DrG

Active Member
That is an incredibly crude circuit, no discrimination or lighting compensation - it will be switched by any form of illumination above the threshold set on the preset pot, not just a laser.

They will be virtually the same as Gary's circuit in the first post in this thread, but with the 100K and LDR swapped (and an adjustable preset in place of the 100K), but with more LEDs and to work on 9V.
Agree completely. Looks like a CdS with you setting (turning the pot) the trigger level of a comparator...simple enough so that even I could do it. Still, the OP would likely benefit from building it and it probably works well, within obvious limitations. If you want to learn a little and do some soldering and end up with something you can play around with, it is not a bad option in my opinion.

I actually ordered an arduino starter kit tonight to try and educate myself on things a bit :)
I don't have on, but given what you want to do, you may want to check this out...

Assuming that you ordered an Arduino UNO kit, a "shield" is a circuit board that mates with the Arduino - plugs right on to the UNO. Again, I can't vouch for this one, but this shield is designed to create your own laser target games, and it looks like it includes a counter and buzzers and the like. Search around and you might find out more about it and at US$11 from China, +$2.60 shipping (don't how that will translate for you), it may be a lot of fun.
 

DrG

Active Member
Yeah, that is a common starter kit that includes lots of stuff to play with and, for that, I think it is a very good idea. You will get hooked in no time....or you will get frustrated, believe that you bricked the dang thing and toss it while cursing loudly.

_____

If you look at the game shield that I posted in #16, the provided link shows the schematic and some sample code for using the shield. You actually have to solder all the components to the provided board and that board plugs right into the UNO that is included in your kit.

You can see that the targets are simple resistor dividers with a fixed resistor on top and three CdS light-dependent resistors on the bottom (which form the target area). The voltage at the junction will change when hit by the laser pointer. The Arduino has several analog to digital converters that can read voltage and provide a number that represents the voltage. Each target is connected to one of the converters. Thus, when the digital value read indicates a hit, the program can operate the buzzer and LEDs and any thing else that you can program to happen. That may not make any sense to you now, but it will.

The code also shows how to calibrate the targets for ambient light. I am certain that they will not work well in very bright light because they would already be near their maximum response - although you could do something about that.

Again, it is a pretty simple board but, low-priced and very UNO friendly - I am tempted to get one....but then I would need to get a laser pointer "gun"...then I would want to build new targets that pop up and twirl and play different sounds effects when hit and play disparaging taunts when missed and so on and so forth...and I really don't have the time ;).
 

jarvouk

New Member
A quick question re this kit:


Would it be possible to hook up more than one ldr in parallel on that same circuit or would that mess things up?

I wanted around 7 to make a nice circular target. In my ignorance I thought so long as only 1 is hit then it would function the same.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
Yes, you can parallel several, but it will also need the sensitivity adjusting as each will be partly conducting due to ambient light.

If you want a low component count and very adjustable sensor, an LM311 comparator would be a good basis.

Connect a preset pot (eg. 10K) across power with the wiper to the negative input, then a resistor (1k?) from power to positive in and the LDRs from positive in to 0V.

The output will go low when the light level is high enough. You can connect a LED and resistor in series from collector output to power +, or a low current relay coil with a flywheel diode, to switch a high power device.
Connect the emitter output to 0V.

It should work well on a 12V supply.


A quick google search finds something nearly identical, though for lower voltage and lower light levels:

The LED resistor should be higher for 12V, eg. 680R to 1K, and the 33K feeding the LDR much lower as you only want it to switch with high intensity light.
 

Latest threads

EE World Online Articles

Loading

 
Top