LIRC

This is the basic receiver designed by Ralph J. K. Metzler (rjkm@thp.uni-koeln.de), the author of LIRC.

GND o--------------------------------+------+
                                     |      |    +-------------------------+
                              C    -----    |    |      SIEMENS 444        |
   e.g. 1N4148    R1 (5K)   (10uF) -----    +----+ -    SFH 506-36         |
      |\ |         _____          +  |           |                         |
RTS o-| >|--------|_____|------------------------+ +    ##############     |
      |/ |   |                                   |      ##############     |
            | |                                  |                         |
            | | R2 (10K)                    +----+ <- signal               |
             |                              |    |                         |
DCD o---------------------------------------+    +-------------------------+

In Germany you can get the SFH 506 e.g. from ELV-Elektronik for 7.95 DM (approx. $4.30). So, the whole device (including a 9-pin plug with casing) should not cost much more than 10 DM (< $7).

The SFH 506-30 (Best.-Nr.: 20-164-48) is best for a 30kHz carrier, the SFH 506-36 (Best.-Nr.: 20-169-58) is best for a 36kHz carrier. Since most remotes use a carrier frequency between 35 and 40 kHz, I use the 36kHz version. Only a few use 32 kHz, so 36 kHz is closest to most. According to the data sheet, which you can find in doc/sfh506.pdf, there are also a few other versions of the SFH 506. If you know a cheaper source for the SFH 506 or got the "circuit" to work with a different receiver, please drop me a mail!

I don't want to advertise for SIEMENS or ELV, they are just the only ones I know about. Several people mailed me that Radio Shack offers a similar device. Please tell me if and how you got it to work with lirc. Alternate receiver circuits will be collected in doc/receivers.

For people concerned about their serial port: according to the data sheet the SFH 506 only draws about 1mA during normal operations and the RTS line is also used as a power source by most mice. R1 keeps the maximum current below 2mA and the SFH 506 from getting a too high operating voltage. You can also use a 78L05 (5V, 100mA) low power voltage regulator to supply the SFH506 with exactly 5V.

R2 pulls up the DCD line to 10-12V (the logical "0" of the RS-232C protocol, but DCD=1 !). If your serial port delivers higher voltages you might want to use a bigger resistor! When an infra-red signal is received the SFH pulls DCD down to ground, which should already be interpreted as a logical "1" (DCD=0) by the serial port. You can probably increase R1 and R2 by a few K Ohm before the device stops working. I will of course take no responsibility if any or all parts of your computer go up in smoke.


Here is the diagram of a receiver circuit using a Mitsumi receiver module sent to me by Looc ?(have to look up the last name in another mail I don't have at home right now...)

Here's the schematic of the receiver. It's very similar to yours...

GND o-------------+------------------+------+
                  |                  |      |
               +-----+               |      |    +-------------------------+
               |78L05|        C    -----    |    |      MITSUMI            |
               +-----+      (10uF) -----    +----+ -    IR PREAMP          |
      |\ |       | |     _____    +  |           |      KEY-COOSV          |
RTS o-| >|-------+ +----|_____|------------------+ +                       |
      |/ |   |                                   |      (printed):         |
            | |          R1 (~1K)                |      0924G              |
   R2 (10K) | |                             +----+ <- signal               |
             |                              |    |                         |
DCD o---------------------------------------+    +-------------------------+

The 78L05 is a low intensity (<100mA) voltage regulator. I've tried R1=2.1K and it worked. I've written what is engraved on the detector (and also what is printed, which is probably some kind of version number, or encoded date).


Here is the circuit I [Jason Kohles <robobob@mindwell.com>] used, with appropriate Radio Shack part numbers and prices, which should be of interest to anyone building these in the US, as Radio Shack is EVERYWHERE around here (There are 3 of them within walking distance of my house).

GND o--------------------------------+------+
                                     |      |    +-------------------------+
                               C1  -----    |    |                         |
       D1           R1             -----    +----+ GND                     |
      |\ |         _____          +  |           |                         |
RTS o-| >|--------|_____|------------------------+ Vcc     I1              |
      |/ |   |                                   |                         |
            | |                                  |                         |
            | | R2                          +----+ Vout                    |
             |                              |    |                         |
DCD o---------------------------------------+    +-------------------------+


Item                                    Label       RS Part Number    Cost(US$)
10 MFD Electrolytic Capacitor            C1          272-1025          .59 / 1
IN914 Diode                              D1          276-1620         2.29 / 50
IR Detector Module                       I1          276-137A         3.59 / 1
4.7k Ohm Resistor                        R1          271-1330          .49 / 5
10k Ohm Resistor                         R2          271-1335          .49 / 5
Project Box                                          270-230          1.99 / 1
25 Pin Female DSub Solder Jack                       276-1548         1.99 / 1
25 Pin DSub Hood                                     276-1536         1.99 / 1

Throw in a little wire and a little solder, and you have yourself an IR receiver. I chose to use a fairly large (1x2x3 inch) project box rather than build the whole thing into a DSub hood, first because I dont like working on tight little projects, if possible I like to have some room to work, and second, because that way I can plug the serial cable into the back of my computer, and put the little "black box" on top where the remote can point at it.

This receiver has an effective range of over 40 feet with my RCA remote that came with a VCR (over 40 feet because with the computer in the bedroom, and pointing the remote in the kitchen window, it is about 40 feet, and that is as far as I can test without jumping over my neighbors fence.) I am sure it would have better performance with an IR filter over the receiver (I get a lot of ambient signals as it is now), but I couldnt find one at Radio Shack, and I havent looked around yet.