difference between IR receivers

Thread Starter

dell101

Joined Jan 21, 2017
6
Hi Guys,

Can someone please help me understand the purpose of the protective shield on the IR Receivers.

Is it shielding from physical damage?

upload_2018-4-18_22-15-33.png

upload_2018-4-18_22-15-43.png

In market both types are available so I want to know which one is for me.


Thanks,
 
The second one looks like the ubiquitous TL1838 / VS1838B type module. They have the IR diode along with some amplification and a filter. I just happen to be fooling with one at the moment. What you are calling the protective shield is likely an IR filter (I know these modules have them) and encapsulation for multiple components....I would guess. These filters are a good idea as even a very powerful and sensitive receiver can be rendered useless by interference.

There are lots to choose from and lots of documentation out there....

Here is a datasheet for the AX-1838HS...and a TSOP382 type
An app note here and intro article here.

If you have a very clear idea of exactly what you need, you should be able to consult the datasheets to make an informed choice. If you just want to decode some signals from a remote for S&G, one of these may work very nicely for you as they do for me.
 

Bernard

Joined Aug 7, 2008
5,262
There are IR receivers which which operate on specific frequencies like 36 kHz, & require seperation between code bursts & those where frequency is unspecified, operating interrupted continuous wave. Example: OPL561-OC ( open collector ), broad wave IR pk. at 800 nm. active low.
 

be80be

Joined Jul 5, 2008
1,930
The one's with the metal shied don't seem to pickup noise like like the ones without.

I have some Tsop 1140 I got like 50 they pickup lots electric field disturbance

But I have some AX-1838HS they just seem to wait for the remote with no output till you press a key.
Where as the Tsop 1140 sends crap out and floods the serial program with a bunch of missed key not recognized
errors.
But it get's the key when the remote is pressed.

Heres a good little pinout glide i found if you ever get into saving these.
lot's of stuff have them so I save them.

ir_module_packages.gif
 
Last edited:

ebp

Joined Feb 8, 2018
2,332
It is an electrostatic shield, which can improve performance in electrically noisy environments. Note that the shield is connected to the centre lead - "ground". The amplifier internal to the device can operate at very high gain in the absence of an IR signal. Either signal or noise that is "in-band", meaning within the signal frequency range to which the device responds, will cause the gain is reduced by an automatic gain control (AGC) circuit. If noise can be kept out the circuit the gain can be kept high while waiting for an IR signal, allowing response to a weaker signal.

The shield would also add a measure of protection against electrostatic discharge.
 
It is an electrostatic shield, which can improve performance in electrically noisy environments. Note that the shield is connected to the centre lead - "ground". The amplifier internal to the device can operate at very high gain in the absence of an IR signal. Either signal or noise that is "in-band", meaning within the signal frequency range to which the device responds, will cause the gain is reduced by an automatic gain control (AGC) circuit. If noise can be kept out the circuit the gain can be kept high while waiting for an IR signal, allowing response to a weaker signal.

The shield would also add a measure of protection against electrostatic discharge.
Ok, I got ya on the shield and I note that I did not mention that (or know that) in my previous post....but is this an IR filter (see pic)?

Screenshot-2018-4-18 AX-1838HS DataSheet - AX-1838HS_datasheet pdf.jpg

From:http://cpre.kmutnb.ac.th/esl/learning/ir-receiver/AX-1838HS_datasheet.pdf
 

ebp

Joined Feb 8, 2018
2,332
Yes, the encapsulant will pass IR and block almost all visible light. It saves having to use a separate optical filter. You can get acrylic sheet that is made for this purpose, but probably not from you local plastics supplier unless you special order it. Visible light, especially from sources with high "ripple" like fluorescent lamps with magnetic ballasts and some LED lamps) is another source of what amounts to noise that has to be rejected.

These IR receivers are a big improvement over what was typically used when I first started playing with IR receivers years ago. Most circuits were very similar to what would be used for ultrasonic remote control except a photodiode replaced the ultrasonic transducer. The circuit required significant gain, fairly sharp filtering and a detector, usually with AGC tossed in. You could fit the circuit on a business-card sized PCB.
 
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