Introduction: RS-232 Infrared Receiver in a Serial Connector (LIRC) Computer Remote Control

Picture of RS-232 Infrared Receiver in a Serial Connector (LIRC) Computer Remote Control

This instructable intends to show you how to create a small & simple infrared (IR) receiver for your computer. The configuration of the software is beyond the scope of this instructable, but I use this receiver with LIRC (Linux Infrared Remote Control) in Linux. You can read more about LIRC and see the circuit diagram I used to build this at

Note that --I did not design this circuit-- and I wasn't the first to put the circuit into a D-sub connector... but I was the first to post an instructable on it, so hopefully someone will benefit from this : )

My total cost was about $1.50 because I had to purchase an IR receiver, but everything else I had lying around because I'm a computer guy/electronics geek.

Step 1: Parts Needed

Picture of Parts Needed

Here are the parts I used, all of them were cannibalized from old projects or scavenged from the engineering lab except the IR receiver that I ordered from Mouser.

Parts List:
Vishay TSOP1138 IR Receiver
50v 4.7uF capacitor
4001 Diode
4.7K resistor
7805 voltage regulator (5 volts)

Parts Discussion
TSOP1138 IR Receiver: Most people use the Vishay TSOP 1738, but Mouser was out of those when I ordered and the 1138 is comparable... and it worked, so who cares : )

4.7uF capacitor: I used an axial 50v barrel (electrolytic) capacitor because I had one available and didn't want to spend 75 cents at Radio Shack. But, if you've got a 4.7uF ceramic disc capacitor, it would be a lot easier to fit inside the D-sub housing we're going to use. Also, since I used a 50v capacitor and we're only pushing 5v, it's going to have a pretty long rise time but it shouldn't affect the performance of our device too much.

7805 voltage regulator: I used a big one made by Motorola in the first one of these receivers I made and I had to clip the pins very short and clip and grind the top pole in order to get it to fit in the D-sub (see pictures of completed project). However, when I was digging around for pieces today, I came across a surface mount 7805 that I got from Texas Instruments as a sample years ago. It's tiny and perfect for this project. I'll definitely use it the next time I build one of these as it will cut the footprint of the circuit down tremendously. Both the large and small 7805's are labeled in the electronics closeup picture.

Step 2: Circuit Assembly

Picture of Circuit Assembly

Once again note that I did not create this circuit diagram. It was made by Trimbitas Sori and can be found on his blog.

The only part of this diagram that may require a little explanation is the pins on the serial connector:
RS-232 Pinout :
1 = DCD (Carrier Detect)
2 = RXD (Receive Data)
3 = TXD (Transmit Data)
4 = DTR (Data Terminal Ready)
5 = GND (Ground)
6 = DSR (Data Set Ready)
7 = RTS (Request To Send)
8 = CTS (Clear To Send)
9 = RI (Ring Indicator)

As you can see from the circuit diagram, we're only using DCD (pin 1), RTS (pin 7), and GND (pin 5). I've included a second image on this page that shows the pin numbers and labels graphically, but all the 9pin D-subs I've ever worked with have been labeled (however microscopically). Note that this image came from an IRIX book, strangely enough. Just ignore the "not used" notes because we're totally going to use the DCD pin for our purposes : )

It's pretty hard to give you step by step directions on this part because our goal is to make the thing as small as possible in order to fit it in the D-sub connector. I'll give you a few pointers but it's going to be up to you to figure out how to make it fit.

1) Before you try to make this really small and fit into a tight space, try building the circuit on a breadboard to make sure you can do it (and have all working parts). It will make you extremely angry if you spend an hour cramming/soldering pieces into a D-sub then it doesn't work because you have a dead receiver.

2) Cut the pins on the components down very short. However, remember that you can only make them shorter so don't cut off too much until you're sure of the size you need and that you can still solder to it. OK, I lied a little bit, if you do hack off too much of a pin, you can always solder an extension pin onto it or a small piece of wire that you can run wherever you need (don't be embarrassed, we've all done it : ).

3) Don't use wire to connect the pieces unless absolutely required. Just solder the components directly to each other. I think I ended up using three pieces of wire to make connections because it was impossible to bend the components the way I needed them to fit.

4) Lastly, just solder on one component at a time, then check to make sure you can still fit everything in the D-sub.

If the circuit diagram below doesn't quite make sense to you, I'm going to try to walk you through the assembly in the next step... some people learn better by having things laid out in text and since we're not using wires I had a little trouble visualizing how everything should be hooked up directly.

Step 3: Circuit Walkthrough

Picture of Circuit Walkthrough

First of all, I'm going to try to avoid telling you to solder pin1 to pin2, and give you more english directions. The problem with this is that english is ambiguous, just ask any computer scientist : )
The only component I will refer to by pins is the 9-pin serial connector because I gave you a pretty diagram in the last step so everyone should be able to figure that out.

So, in order to try to make the english explanation less ambiguous I'm going to set out a few rules.
1) I will say that a component is 'on its back' which will mean the following:
a) The IR receiver is 'on its back' when the rounded receiver side is up and the flat side is down.
b) The voltage regulator is 'on its back' when the totally flat side is down and the two level side with printed letters is up.

Here we go:
1) Solder the dark side of the diode to pin7 (RTS) on the serial connector, that is the stripe indicating direction will be on the opposite side of the diode from the serial connector.
2) Solder the striped end of the diode to the center pin of the 7805 voltage regulator
3) Solder pin 1 on the serial connector to the resistor.
4) Solder the other end of the resistor to the left-hand pin on the 7805 voltage regulator assuming the voltage regulator is -on its back-
5) Solder pin 1 on the serial connector (where we just connected the resistor) to the right-hand pin on the TSOP1138 IR receiver, assuming the receiver is -on its back.-
6) Solder pin 5 on the serial connector to the negative side of the capacitor
7) Solder the positive side of the capacitor to the center pin of the TSOP1138.
8) Solder pin 5 on the serial connector (where we just connected the negative side of the capacitor) to the left-hand pin of the TSOP1138 (assuming its on its back)
9) Solder the center pin of the TSOP1138 (where we just connected the capacitor) to the right-hand pin of the 7805 voltage regulator, assuming the voltage regulator is -on its back-

Keep in mind that several points will have multiple connections. For example, the center pin of the TSOP1138 connects to the positive side of the capacitor as well as the right-hand pin of the 7805 voltage regulator, assuming the voltage regulator is -on its back-

Okay... so that's really, really nasty and I would never figure how to build a circuit like that... but perhaps it will help someone who doesn't read circuit diagrams very well.

Step 4: Stick It in the D-sub

Picture of Stick It in the D-sub

Now, if you took my advice, you've been stopping between every solder point and fitting the circuit into the D-sub to make sure it works. If you didn't take my advice... well, good luck.

Assuming you've been test fitting the circuit every step, this should be really easy. Just drop the circuit in and make sure no connections short to each other. If you have overlapping contact surfaces, just cut a small piece of electrical tape and squeeze it in there to insulate them. You could also use liquid electrical tape and coat everything inside... but that stuff is really messy and a royal pain if you ever have to work on this again so I'd recommend against it.

The last thing?
The last thing you should have to do with the D-sub is dremel out a rectangular area where the IR receiver can stick out the top. You'll also have to dremel a notch for the rounded receiver area. This doesn't take too long, but try to be fairly precise. If you can keep the area tight enough then the serial connector and pressure on the IR receiver from the D-sub casing will keep everything safe and snug.

Test him (or her) out.
Once everything is insulated, plug the little guy in and test him out. You'll probably want to do this before completely closing up the D-sub just in case you screwed something up : )

If it doesn't work, compare your circuit closely to the circuit diagram and retrace/recheck all of your connections.

Step 5: Plug It In!

Picture of Plug It In!

Once you've tested and completely closed the D-sub, plug it in and then go about setting up your software. Personally, I had more trouble setting up the software than I did building the circuit but your mileage may vary.

Attached are a few shots of it plugged into my desktop and laptop.

If I missed anything or if you have any questions, please feel free to comment or message me and I'd be glad to help or add corrections.



zshtiwi (author)2013-05-09

nice circuit

darc (author)zshtiwi2013-05-31

Thanks zshtiwi but I want to make it clear that I did not develop the circuit diagram, the credits can be found at the head of this section. I just crammed the damn thing into a D sub : )

swg (author)2012-06-20

will HYPER TERMINAL display any data (character/HEX value) when a key pressed in remote(any remote).

tfe (author)2011-06-25

it work DB9-RJ45???

zack247 (author)2011-02-05

is there anything significant about the IR reciever? if theres anything special built in to the small package, is there any way i can make a general 2-pin IR detector work for this?

darc (author)zack2472011-03-27

Sorry for the delay in getting back to you, I've been traveling.

You can see here :

That the receiver has some extra innards (preamp, diode, etc) compared to a simple IR detector.

You could certainly use a regular IR detector, but you'd need to work out the rest of the requirements. And, the receivers run about $1 so it may not be worth the hassle - unless you just want the challenge : )

tajmohd15 (author)2010-10-24


which remote control should be used to this RS-232 Infrared Receiver in a Serial Connector (LIRC) Computer Remote Control.

is it a universal Infrared Receiver

please reply me

darc (author)tajmohd152010-10-26

Any remote that transmits an IR signal at a receivable frequency should work. I used a 38kHz IR receiver and that's pretty standard (as is 36kHz).

Personally, I've used this receiver with an RCA Universal Remote (model RCR815) the most and it works great. I've also tested it with the remote that came with my Logitech PC speakers (5.1 with 10" sub... I forget the model number), my old Sanyo DVD player remote, and a few other remotes from various devices in my home. They've all worked (in that the receiver picked up a signal) but I didn't bother to map the output from the remote to an action in LIRC on all of them... I just wanted to see if they'd pick up. The RCR815 is the one that I've used the most and is the only remote that actually gets used in my house.

Remember that you'll have to configure your receiver software to make it actually "do stuff" but that the receiver will pick up the signal from a ton of different remotes/input devices.

Good luck!

tajmohd15 (author)darc2010-10-28

can u please tell me how to make in usb version

darc (author)tajmohd152010-10-30

I'm just going to copy/paste this reply from further down because I'm lazy : )

There are USB alternatives, but they're a little more complicated because you have to interface with the USB controller... which is trickier than the serial controller. Because of that, you'll have to have some type of IC or MC to do the communication between the IR receiver and the USB bus. And, with the added hardware, your cost will raise a bit. Of course, I built my serial receiver for about $1.50 ... so "rising cost" may come up to $5, probably less than $10... depend on the IC/MC you use.

Check out these projects for more info, and for a schematics/plans:
USBTiny :

USB-IR-Boy :

I'm sure there's probably a few more projects out there, but these are the two I hear about the most often.

tajmohd15 (author)darc2010-11-21

in usb Cant we connect

DCD to red wire
RTS to white or Green wire
GND to Black wire

darc (author)tajmohd152010-11-21

I've never looked at the USB options in depth, but if you're talking about wiring the IR receiver directly to USB wires without a microcontroller... I don't think that's going to work out for you.

tajmohd15 (author)darc2010-11-16

in usb Cant we connect

DCD to red wire
RTS to white or Green wire
GND to Black wire

matstermind (author)2010-11-11

do i need to restart the computer before i plug it in or can i just stick it in.

darc (author)matstermind2010-11-11

You can just plug it in - RS-232 is hot swappable.

If you're in windows, you may need to scan for hardware changes. Or, the receiver software you're using may be able access it directly... I'm not sure about Windows, I'm a Linux guy.

On Linux, you just plug it in and then point LIRCD to the correct port (after proper configuration) and alls well.

matstermind (author)darc2010-11-11

ok, thanks

matstermind (author)2010-08-19

is that a 4148 diode? it looks like a 4001

darc (author)matstermind2010-10-26

You are quite right! It is a 4001 in the picture above.

I had used a 4148 zener on a different version of the same circuit and must have gotten them mixed up when I wrote the instructable. I'll get that fixed.

Thanks catching that!

matstermind (author)darc2010-10-28

your welcome, do you know if

a. either diode can be used
b.does it work with windows 7

darc (author)matstermind2010-10-30

A) A zener would be fine if you didn't exceed the breakdown voltage of it... I'd just go with the 4001 to be safe.

B) It should work with Windows 7 as long as there is software that is supported on Windows 7 to handle IR transactions from a serial port. Unfortunately, I don't know much about what's available for Windows because I'm a Linux geek. So, I'm not too much help there except to say that the hardware should be fine, but you may have to seek out some appropriate software.

matstermind (author)darc2010-10-30

ok, thanks

infraredman21 (author)2008-08-07

Well, hello there i'm Chris i'm a big computer junky my self but the only computer that has that seral port is very old my new computer only has usb, now do you thing we could make one thats a USB??

dleite (author)infraredman212010-08-31

You could do a USB one from scratch, ( I was able to get my XBOX DVD Remote to connect to Linux via LIRC). A simple solution may be a USB to Serial device and driver.

kiwitom (author)2009-10-28

Thanks for the tutorial, I found it really helpful, still having some problems though. When I tried to learn my remote, winLIRC kept coming up with errors regarding consistency of the signal
1. Is there a general discussion forum for these devices where I can post these questions or is this it?
2. I used the following receiver: The RPM1700 series from jaycar: How does this stand up to the TSOP1738? I noticed the RPM1700 does not filter out flurorescent light and it seems to be having trouble consistently reading the signals from my Panasonic remote but this may lay in other parts of the cirucuit.
3. Is there a list of compatible remotes or frequencies so I can see if my remote is actually compatible?
4: I used a 10K pull up resistor instead of the 4.7K, I can't see how this could cause any problems, is this true?
5. Does it matter if the diode I used is not the same as the reccomended one? I used one which was made for slightly higher currents because it was the only one I had

matstermind (author)2009-09-30

can i use any infrared receiver?

darc (author)matstermind2009-10-04

The easy answer is "yes" but there are things you'll need to take into account. As with all electronics, you'll need to make sure that you're supplying the correct voltage/current to it (you'll be able to find a spec sheet with this info online - for example). Also, you'll need to figure out the bandpass of the IR receiver you intend to use. The TSOP1138 that I used is a 38kHz, which is a widely accepted standard for IR communication. I've read of people using 36kHz receivers without any problems, but your mileage may vary.

Good luck.

matstermind (author)darc2009-10-04

i have some from old VCRs, ir control toys, and similar stuff. i don't know the voltage. or the bandpass. or even the part number

darc (author)matstermind2009-10-04

There's usually some type of identifying number on the part. Just type that into google along with a brief phrase like "IR receiver" and see what you come up with. -darc

matstermind (author)darc2009-10-05

one has 015, the other N 8.

Kato_Potato (author)2008-09-04

This is awesome! This is exactly what I want to do. The end product looks so neat and tidy, I love it! I excited to get the supplies and try it out. I looked on the mouser website for the IR receiver and saw that they don't have the same model you used or the 1738, what should I look for in the specs to make sure I'm buying something that's about right? I'm new to the whole electronics building thing so I have a stupid question: does this widget need a clear line of sight to my remote control? I'm happy to set it up so that it will, but it would be helpful to know in advance so I can plan accordingly. Also, the remote control I want to use works on other devices at 20+ feet, will it also work on this receiver at 20 feet? Thank you so much for putting together this tutorial. I'm looking forward to following the step-by-step as soon as I get all the supplies.

darc (author)Kato_Potato2008-09-04

Sorry, I failed to answer all your questions... let's try again : ) >Does this widget need a clear line of sight to my remote control? No, not necessarily. IR signals will reflect off of most smooth surfaces such as walls. But, they don't behave like RF signals where they radiate from the source and go through walls, etc. >Will it also work on this receiver at 20 feet? Yes, that shouldn't be a problem at all. It depends on more on your remote control's power than the receiver. It the remote can generate a strong enough signal to go 20ft for other devices, then the receiver will have no trouble picking it up.

darc (author)Kato_Potato2008-09-04

The original TSOP-1738 is :
4.5v - 5v
supply current : 1.5 mA
output current : 5 mA

I looked around Mouser a little bit for IR receivers (optoreceivers) and found a TSOP-2238 which looks comparable.
Datasheet :
Specs :
4.5 V - 5.5 V
Supply Current : 1.5 mA
Output Current : 5 mA

Looks like that matches up perfectly and should work for you. The structure of the receiver itself is a little different from the one in this instructable - it looks shorter and fatter in the data sheet. However, all the specs are the same, including the viewing angle (90) so the only difference will be how to fit the receiver into your D-sub - you may have to do a little more cutting.

They're $1.10 each and here's the link :

Let me know how it goes or if you have any other questions.

lil Smart Kunt (author)2008-08-09

Dude I have TWO of them And thry are fancy i made it like ages ago if you have something to say about that please replay me dont hesitate

rO_rOyrO (author)2008-08-07

Your Tsop is a good idea too and i´m sure that it works very well. And what sofware have you choose¿?This the wors part of the remote control. Nice work

darc (author)rO_rOyrO2008-08-08

I've been using LIRC ( on a Linux desktop.

rO_rOyrO (author)2008-08-07

Hi...i have find other remote control for pc in this page.I do it and it work well...


However you will have problems to find the IR Tsop

Thanks Darc for your project

darc (author)rO_rOyrO2008-08-07

Ah, thanks for the link. On the TSOP, the 1738 is routinely the "recommended" receiver, but I used the TSOP1138 with no issues (because I couldn't find the 1738). But, make sure you review the specs for the system you're going to use it with...

brodyf (author)2008-01-06

As GorillazMiko already said, I am impressed by your ability to keep it so compact. This is really great.

GorillazMiko (author)2008-01-05

Woah dude, nice job, you do some pretty insane soldering. Really clean and neat, looks nice, small too, about the size of a quarter (as you showed.)! Nice job.

darc (author)GorillazMiko2008-01-05

Thanks for the comment! I don't know about "clean and neat" but it got the job done : )

GorillazMiko (author)darc2008-01-05

Just wondering, what kind of soldering gun/ iron do you have?

darc (author)GorillazMiko2008-01-05

I typically use a really cheap/old radio shack 15w iron. I've filed down the tip to a sharp point (which everyone says you're not supposed to do) and have to refile it every year or so. When I was still in college I'd use one of the beasty 60w irons in the engineering lab, but don't have access to that anymore. One of these days I need to upgrade to a nice 30 or 40 watt iron... but I'm really cheap.

About This Instructable




Bio: Just a geek with a soldering iron...
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