I don't think that will work. That module requires a carrier frequency (on/off) at one of the design frequencies, such as 38KHz. Then the carrier needs to be modulated at about 1.7 KHz (i.e., 600 uS bursts). See the timing diagrams near the end of the datasheet (http://pdf1.alldatasheet.com/datasheet-pdf/view/26656/VISAY/TSOP4838.html).

Something like this that uses one half of a 556 to generate the carrier at 38 KHZ and the other half to modulate it will work. If you want the PCB layout, just say so, and I will provide it. Might be best by PM, so I can send the actual Eagle files rather than just images.

I can say from experience, though, it is much easier with a microcontroller. You can do everything with one chip - I used the 12F509 - and have much better control.

John

 

hi jpanhalt

Thank you for your reply, yes please can you give me the pcb layout and what i need componets i need to do this.

Can you tell me how to pulse the od50 on and off at the correct speed to get it to work?

Regards
Stephen

 

I will put together a package of information and send it this morning.

Basically, the way it works is that IC1A in the schematic produces the 38 KHz carrier for the IRED, D3. IC1B modulates that carrier by turning it on and off. Notice the connection between the output of IC1B and the reset pin of IC1A (pins 9 and 4, respectively, on the 556). I don't know the current requirements for the OD50 off-hand, but remember the 556 is limited to a maximum drive of 150 mA. For a little more current you can use separate 555's, or you may need an amplifier stage to up the drive current even more.

John

 

Hi John

Thanks for your reply, i was looking to drive the od50 at 500ma. I take it that d3 will be my od50 led? are d1 and d2 just diodes? not leds? What size of capacitors and resistors will i use?

Did you get my private message with my email address on it?

Thank you very much for your help.

Steve

 

Those assumptions are all correct. I also noticed - too late - that the schematic I grabbed did not have the values on it. The diodes (almost anything will work, I used 1N4148) in 555-based timers are quite common, as they allow better control of the duty cycle. I will include the component values in the PM and will probably update the schematic here as well.

We woke up to 20 cm of snow, which I need to shovel first. So I may be an hour or so. John

 

Hi john

Thanks for your reply once again. So if i build the circuit and use the reciever circuit i had posted should it work? Running the od50 at 500ma gice me the distance of 30 meters to make my link work?

Many thanks for all your help
steve

 

Hi,

Can anyone tell me if my circuit diagrams look ok or what i would have to do to them to make them work as expected.

The 555 timer circuit i have calculated to give me a 0.5 second on time 0.5 second off time feeding the IRLZ34 and therefore pulsing the od50?

Should this work or what should i do to make it work?

That won't work.
The IR receiver module should see at least 10 cycles ON followed by at least 14 cycles OFF at 38kHz, to be able to use it for continous transmission. Otherwise the error correction will discard the signal as noise.

The circuit below should be adjusted for for 1kHz (i.e. 500µs on and 500µs off, which equates to 19 cycles of each ON/OFF).

A 1:1 PCB Layout in PDF is here.

And a PCB overlay is here.

 

Hi All

Ive built a circuit as attached which jpanhalt has been helping me with.

What sort of voltage levels should i be getting at pin 5? i am getting around 1v. Should this not be switching? Wouls it matter greatly if R4 was 6.9K and R5 was 5.7K as it was the cloest i could make them with the resistors i had?

When i look at my led with a camera phone it appears to be on constly. Anyone and ideas on what could be wrong?

Regards
Steve

 

I have been off-line all day due to a hard drive failure (corruption of the boot section and file allocation table) and still have not gotten everything reloaded. I am limited in what attachments I can open right now and could not open the doc file. I can say that the IRED should blink at a rate that you will perceive as constantly being on. Similarly, the voltmeter is unable to respond at the rate of the output. Have you looked at them with your oscilloscope?

John

BTW: Found a really great recovery program. But that is for another forum, I guess.

 

Hi john

No i have not looked at it yet with the oscilloscope i will have to do that. Just though it was not working correctly when i saw the led which looked to be constantly on.

Thanks again
steve

 

So i have my IR transmitter circuit working now and just built the reciever circuit as shown in the link

http://i274.photobucket.com/albums/jj266/sjfphones/irreciever.jpg

When measuring my voltages on the output from gnd and pin 1 (the output pin) what voltages should i expect to recieve when no IR is being sent and then when IR is being sent?

 

Hi,

When measuring my voltages on the output from gnd and pin 1 (the output pin) what voltages should i expect to recieve when no IR is being sent and then when IR is being sent?

When IR is on => 0V (or at least less than half a volt)
When IR is off => close to 5V

 

Hi Soren

thanks for your reply. When my IR is off im gettin my +5volts but when IR is being recieved its only dropping to around 2.5 volts. Any ideas of what could be wrong? This is at quite a short distance of around 50 cm away from the IR transmitter.

Regards
Steve