Building a very simple IR-Switch with kids: Help needed

[Schorhr]

Hello, I am looking for a very simple and inexpencive infrared-switch circuit to build with kids.
It only needs to switch on/off, no decoding required.
The kids shall recieve a construction kit and manual. The aim is to build a boat out of styrofoam, wood and of course the electronics.
To use just one channel/function I thought of using a Counter IC such as the 4017, so they could switch both motors on, and then switch to left/right/off.
here is a small sketch, think of the lights as motors.

**broken link removed**


The IR-reciever diodes I tried using where just too daylight-sensetive, so I stumbled across the TSOP modules. I am not happy with it since using it is a bit too advanced for kids (and also for me, I am also a electronics beginner, but I am allways looking for fun experiments)... But i had no better idea yet.

I have searched on this forum but have not found any project thats easy enough. Also in other german forums I have posted in no one had a easy idea or sggested microcontrollers; While I find the attiny pretty cool its just too complicated (I am talking preschool to 3rd grade here....)

Maybee someone here has a better & easier Idea, but the best shot I got so far is the idea to use a TSOP IR Reciever module. As far as I understand the datasheet, it will output "1"/"on" when no valid IR Signal hits it.
When a 38 KHz (or whatever TSOP it is) signal hits the TSOP, it will output a sequence of on and offs, the RC5-Signal of the pressed key.
My idea now was to invert the signal and "smoothen" it.
The result would be that at no signal the output would be "0"/"off", and the "0101011" sequence would be a somewhat "on" signal.

**broken link removed**

Here is a simplified shematic of the setup.
The thing at the left represents the TSOP, and is a simple switch in the circuit:

**broken link removed**

I once read that a transistor can be used to invert the signal instead of a inverter-IC, I hope this would work in a real circuit like that. It allready has more parts then I wish it would have. :-(
Here is the link to the source and the java simulator:
https://www.nottoxic.com/wapcc/ae/aqua/ir-rx.htm

Here is a old graphic when i had the idea, its wrong but I drew the parts, so its probably more understandable then the above shematic where i used wires to outline tsop and 4017:
**broken link removed**
(Kondensator is german and means Capacitor, sorry.)

I know there are ready-to-use IR-Recievers out there, but building a small circuit would be fun for the kids, and also buying kits would be too expensive.
I have not checked into the datasheet, but maybee the 4017 is too "slow" for the pulses anyway? Or will it switch on every rc5-bit?

Also, another idea would be to use a 36 and 38KHz Remote, two tspo modules, so the motors could be switched independently, ... and directly through transistors, since the fast on/off would not matter that much? Though building a remote then instead of using two different tv remotes would be better i guess. Unfortunaly I read that the tsop will not respond to a "empty" 38/36KHz Signal produced by a IR LED and a 555? Does anyone know more about this?

I apreceate any help. I experimented a bit with a TSOP, but managed to fry it ;-) So I decided to ask for professional guidance first.

 

[dknguyen]

The easiest thing to do would be to put "hoods" over the IR detectors to block out sunlight.

 

[Schorhr]

What kind of hoods? I allready tried IR-Reciever diodes with a special coating, but they did not bring the result either. Since there are so many different kinds I only got a few they had in stock at the moment.
The TSOP will only respond to modulated 36/38/x KHz RC5-Signals, thats why I decided to use it. I'dd apreceate any simpler setup though

 

[dknguyen]

I had a piece of cardboard in mind that just overhangs the IR from top, left, and right? Like a baseball cap. The IR stuff with the filters isn't what you are looking for...they are so the sensors filter out other wavelengths the elements are sensitive to and operate at. It'd be best if you had them so the detectors only respond to the wavelengths you are emitting. From the ambient environment.

THose filters, however, will allow the same wavelengths present in sunlight to pass and flood the detectors. That's what the hood is for. It just blocks out all the sunlight all together. Make sure you try different materials or overlap the cardboard with another material like tinfoil or something. Just to be sure. Some materials are sometimes IR transparent, and that's what you're trying to block out!

 

[audioguru]

EEK!
The transistor does not have a base resistor.
The transistor doesn't even have a collector resistor. So when the TSOP is off then the transistor shorts the supply.

The TSOP doesn't have the supply filter shown on its datasheet.
The diodes shouldn't be there.
The resistors should not be there.
The filter is not a filter.
The schematic has a BLACK background.
All wires on the schematic are covered with dots.

 

[Schorhr]

Audioguru, no reason to panic
As I wrote this is just a simplified shematic.
It is not intended for construction 1:1. The shematic has a black backgroundand "dots" since it is a screenshot from the java simulator.
Also the transistor does not short the supply. There is a resistor infront of the (-), but as I allready wrote in the first post, its just a quick&dirty concept shematic.
Since I do not know what parts to use yet and if I will use a 9v batterie as powersupply, I left most resistors out untill I know the actual values required.
The diode prevents the capacitor from discharging through the transistor, so it supplies the Clock-In.

dknguyen, I still do not understand. If I shield the Sensor I will have problems transmitting from different angles. The TSOP will only respond to modulated IR-Light, so why not? On other projects I read about it will work in 8-10m distance at indoor daylight.

 

[Nigel Goodwin]

Use PIC's or the pre-programmed Holtek encoder/decoder, that's what the TSOP is designed for - don't try and bodge a 1960's idea on a 21st century component!. The Holtek chips are remarkably cheap - so, for your purposes, are probably better than a PIC.

 

[Schorhr]

Once again, it is not about hightec. Its about a project for kids, that should work with as few components as possible. Microcontrollers are not an option.
Personally I would of course use a attiny or any other suitable microcontroller.
The TSOP does the detection of the IR, so why not (ab)use it like that?

 

[Nigel Goodwin]

Once again, it is not about hightec. Its about a project for kids, that should work with as few components as possible.

Wanting a non-micro-controller solution rather ruins that, you're looking for a LOT of components in comparison!.

Microcontrollers are not an option.

Why not the pre-programmed Holtek ones? (which you don't even know is a micro-controller).

Personally I would of course use a attiny or any other suitable microcontroller.
The TSOP does the detection of the IR, so why not (ab)use it like that?

It detects low duty cycles of 38KHz modulated IR, so you need to arrange for it to receive that.

 

[Schorhr]

I am looking for a simple solution, and not microcontrollers. I would like to even skip the tsop and the 4017, but I have found no other solution if I dont want a 10cm range.
Still, explaining that the tsop is a reciever and the 4017 jumps from pin to pin is still easy to understand (even though more abstract then a resistor or capacitor), while it will get more complicated if I have to introduce a microcontroller that does the decoding and switching.

I have now found circuits with a similar aproach
( https://www.b-kainka.de/bast323.jpg **broken link removed** , **broken link removed** and others )
that also use a sensor like the TSOP, invert it, and switch a relay with it. Seems like some others had the idea before.

Still im considering using two different TSOP without a 4017 now.

 

[Nigel Goodwin]

I am looking for a simple solution, and not microcontrollers. I would like to even skip the tsop and the 4017, but I have found no other solution if I dont want a 10cm range.

Like I said, check the Holtek range of chips specifically designed for remote control, they are cheap and simple to use **broken link removed**

There's nothing stopping you using a photo-transistor or photo-diode, but it's quite complicated to make an effective IR receiver using them.

Still im considering using two different TSOP without a 4017 now.

How would two help?.

 

[Schorhr]

Thanks, I will check them out.
By using two different TSOP-Receivers, one with 36 KHz and the other with 38 KHz (or further appart values), I could simply switch two motors without the 4017-solution, using two (555 based) transmitters.

 

[Nigel Goodwin]

Thanks, I will check them out.
By using two different TSOP-Receivers, one with 36 KHz and the other with 38 KHz (or further appart values), I could simply switch two motors without the 4017-solution, using two (555 based) transmitters.

I wondered if that was what you were thinking? - it wouldn't work, all TSOP receivers I've seen work well with any remote, the actual frequency makes very little difference - but should be adhered to for the absolute maximum range.

You could always try NE567 tone decoders?, use two 555's (or a 556) to send a modulated 38KHz, and tune the 567 to the modulation frequency, then feed that to a 4017. It's a lot more complicated (and limited) than the Holtek solution, and 30+ years old, but it used to work!.

 

[Schorhr]

Too bad. I thought at least 30 & 56kHz would work, since looking at the datasheet (Figure 1. Frequency Dependence of Responsivity) i thought even closer frequency-TSOPs would respond individualy.

The tone decoders are a neat idea, I will check them out, though you're right, its also complicated
If kids and laserpointers would not be a "no-go", I would just let them build a circuit with simple Photoresistors or so, but they will just blind each other ;-)

 

[Nigel Goodwin]

Too bad. I thought at least 30 & 56kHz would work, since looking at the datasheet (Figure 1. Frequency Dependence of Responsivity) i thought even closer frequency-TSOPs would respond individualy.

You could try ones far apart like those - and see what happens, but those are fairly uncommon values - normally the ones you see are either 36KHz, 38KHz, or 40KHz, and seem completely interchangeable (I only keep one type as a service replacement at work, and I couldn't even tell you what frequency it is?).

 

[Gayan Soyza]

The boat will go but it will never come back. Unless you tell a kid to jump into the water & bring the boat back. Kids will love this kind of adventure works.

It will be easy for you if you take TSOP modules. It’s supporting most remote controllers. For a single latch function you can easily build a circuit with a NE555 + latch IC. But it’s also too much for kids. But to control more motors you need to shift the output.

Ex - Press once - turn ON motor1
Press again - turn OFF motor1 & turn ON motor 2 etc……

But to control more than two motors it’s getting more complicated.

 

[Schorhr]

The boat will go but it will never come back.

Why? I dont quite understand what you mean. With the 4017 i mentioned it would be as you described, and with two different tsops and a inverted signal the motors would only recieve power on signal.

 

[Pommie]

Won't a 555 driving a IR LED at 38KHz act as an always ON transmitter. A simple push button in the power supply to the 555 will effectively (and remotely) turn the output of the TSOP module OFF/ON. Feeding this output to a 4017 will give the OP what he wants. Is there something about the TSOP modules that I'm misunderstanding?

Mike.

 

[Nigel Goodwin]

Won't a 555 driving a IR LED at 38KHz act as an always ON transmitter. A simple push button in the power supply to the 555 will effectively (and remotely) turn the output of the TSOP module OFF/ON. Feeding this output to a 4017 will give the OP what he wants. Is there something about the TSOP modules that I'm misunderstanding?

Yes, they are designed for digital modulation, if you send a continuous carrier their AGC turns them down.

 

[Pommie]

In that case, a one shot gating a 38KHz signal generator should do the job. Shouldn't it? Can't a dual 555 be configured to do this?

Mike.