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Old RCA TV - IR remote carrier frequency?

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futz

Active Member
So I've been tinkering with remote control IR. I learned SIRC probably a year ago (you may have looked at the page on my web-site). Tonight I hooked up my Logic to the same PNA4602M sensor and studied Pioneer codes until I understood them (my DVD player is a DV-578A). Just your standard Space-Width Encoding - LSB first, each byte repeated as a 1's complement byte for error checking. Then I looked it up and found that it's called LIRC.

Then I tried the same thing with my ancient RCA TV remote. But the 38KHz sensor doesn't see the RCA remote at all. Anyone know what carrier frequency an early 90's RCA TV remote transmits with?

ir_remote002sm.jpg
 
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Nigel Goodwin

Super Moderator
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Not been a make that's sold in Europe I've no idea, but it's got to be a LONG way away for a normal sensor not to work at all.

Old B&O sets used to use a 100KHz carrier, which pretty well stopped all the OFA type remotes working tham.
 

futz

Active Member
Not been a make that's sold in Europe I've no idea, but it's got to be a LONG way away for a normal sensor not to work at all.
Ya. Guess I'll have to rig an IR phototransistor and measure the pulses. I have some, but they look exactly like LEDs, so I think they're mixed in with them. Good luck sorting them out...
 

futz

Active Member
All those TSOP sensors need a filtered supply. A 100ohm resistor & 4.7uF cap are common. Just like the Junebug schematic shows.
Do you really think not having that filter would be enough to make the sensor completely ignore my remote? I would think that, at worst, it would work badly, but would at least see something.

With my Logic probes connected to the sensor, madly hitting buttons on the remote, I see nothing whatsoever. I've checked that the remote is working, both with the TV and by looking at it with the digital camera.
 
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Nigel Goodwin

Super Moderator
Most Helpful Member
Do you really think not having that filter would be enough to make the sensor completely ignore my remote? I would think that, at worst, it would work badly, but would at least see something.
Without the correct decoupling they are often unstable, and don't work at all.
 

futz

Active Member
Ditch the ancient remote. A new universal remote costs about $5
Hahahaha! :D That's not gonna happen until the ancient TV quits working. :p I'm in no rush to spend big bucks on a television (TV is the mind killer) that I rarely watch. I'm sure TV is fine entertainment if you're a retarded mental defective, but I find it incredibly boring and stupid. It's there to watch the odd bit of news/weather and a movie now and then.

I have a very good universal remote. Logitech Harmony 880 (was about $300). The sensor ignores the 880's RCA output exactly the same as it ignores the OEM RCA remote's. Both remotes work fine with the TV.
 

futz

Active Member
Without the correct decoupling they are often unstable, and don't work at all.
Ya... I don't really think that's it. Both SIRC and LIRC codes are detected perfectly every time by this sensor. I've looked at the sensor's output with the logic analyzer (Logic) many, many times and all seems perfectly normal. Nice clean pulse train. Only with the RCA do I get nothing.

That said, I'm going to add that resistor and cap anyway, just to see if anything changes. :p
 
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be80be

Well-Known Member
Futz I don't know about your RCA remote but I Know this A serial to IR transmitter
that worked with a old 486 Compaq laptop wouldn't pick up.
I was going to reuse the transmitter couldn't get a IR module to pick it up.
After a long time with google I found that the carrier was 30khz.
I think my 40khz IR module thought it was noise
 

futz

Active Member
why not connect the logic to the remote itself and test it to see the pulses it sends and calc from there?
Good idea, but I'm not sure I can get that remote apart without destroying the case. I want it to stay looking and working good for now. It's the original remote that came with the TV. It sucks bad, but it's the only way I have of programming the TV. The universal doesn't do all the setup stuff that the OEM remote does, and you can't do it from the TV front panel (more idiotic engineering by electronics manufacturers).

And regarding bad design, just don't get me started on the Logitech 880. :p What a stupid design! It spits out IR codes just fine, but it's a TOTAL PIG to use daily (the case/keyboard was designed by chimps) and to program (programmable only by plugging into USB on a PC - the original, very cryptic, programming code was IE-only (FAIL!) - now it at least works with Firefox (better)).

Part of why I'm doing all this tinkering is that I want to build my own universal remote that's comfortable (unlike the 880), easy to use and program (unlike the 880), smart as hell (the 880 is pretty smart, but could be a lot better) and fast (unlike the 880 - I understand they wanted to prevent callbacks on it, what with all the various equipment it can control, but it's slow!). The 880's very pretty, but power-hungry, color screen is wasted on stupid little icons instead of real information.
 

AtomSoft

Well-Known Member
heh a remote was my first wanting. But i want to learn alot before the remote like:

POWER CONTROL (SAVING)
COLOR LCD
ALL IR Types (MOST COMMON such as SIRC, RC-5,RC-6, NEC and more)
And IRDA ( the wierd one Lol)
 

futz

Active Member
heh a remote was my first wanting. But i want to learn a lot before the remote like:

POWER CONTROL (SAVING)
COLOR LCD
ALL IR Types (MOST COMMON such as SIRC, RC-5,RC-6, NEC and more)
And IRDA ( the wierd one Lol)
Ya, but I figure (provided I can find enough spare time) I'll build the hardware first, which won't change much. Then the software can be continually updated until it suits me, and updated for new hardware (that old TV is gonna crap out someday). So what if it eats batteries at first, and is still crude softwarewise. It's version 0.001. Good enough. :p
 
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futz

Active Member
why not connect the logic to the remote itself and test it to see the pulses it sends and calc from there?
I looked close and refreshed my foggy memory on the RCA remote. I guess I had had it apart before (to clean the keyboard) and it was pretty easy to crack it open again. Connected the logic analyzer to it and now I can see the pulses just fine. I'm calculating out the frequency right now... Yup, it's 56kHz. Guess the 38kHz sensor filters that out as noise...
 

AtomSoft

Well-Known Member
Good work... My internet was down for a few days im so happy its up . I could only complain for so long :D

Ima have to take apart my tv remote again for my Phillips Magnavox once i get my own logic tool. I cant wait. Work sux and not enough pay towards bills to play with yet :(
 

Sig239

Member
All those TSOP sensors need a filtered supply. A 100ohm resistor & 4.7uF cap are common. Just like the Junebug schematic shows.
Evidently, the sensors now being produced include a built in constant voltage supply, which negates the need of any external filtering. See this datasheet of a sharp sensor I recently used, and this datasheet of the PNA4602M from panasonic that he is using.
 
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