IR remote circuit running out of steam?!

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rshayes
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Re: IR remote circuit running out of steam?!

Post by rshayes » Sat Apr 30, 2005 7:05 am

It appears that WinLIRC has the option of using either DTR or TXD as the output pin. TXD seems to be preferred, and probably simplifies the software and gives more consistent timing. No problem there.<p>At some point, the software initializes the serial port. It can set DTR and RTS in either state at this time. Since no use is made of these signals, thay may, if you are lucky, be set negative, since there is no reason to set them at any particular level. If you don't have a voltmeter, you could use the series diode, resistor, and LED that they show to test the state of the DTR and RTS pins.<p>When TXD is negative, it charges the storage capacitor through the 1K resistor, D2, and the 2.2K resistor in series. The 1K resistor is also part of the signal path when TXD is positive.<p>If you connect a diode and resistor in series between DTR and the negative terminal of the storage capacitor, current will flow into the capacitor from DTR when DTR is negative. The cathode of the diode would connect to DTR, the anode would connect to the resistor. The other resistor lead would connect to the negative capacitor terminal. The resistor can be 3.3K. This is about the same as the two resistors in series from the TXD pin.<p>You can also connect another diode and resistor from the RTS pin to the neagative capacitor terminal. This will give you a little additional current.<p>One of the diferences mentioned between WinLIRC and LIRC is that the port settings are stored in the registry in WinLIRC rather than being fixed by the code as in LIRC. This may be where you can set the status of DTR and RTS and guarentee that they will be negative.<p>The diodes can be the same as D2. Basically you need a small signal silicon diode.

rshayes
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Re: IR remote circuit running out of steam?!

Post by rshayes » Sat Apr 30, 2005 7:15 am

Incidently, the LIRC web site mentions 880 nm and 950 nm infrared diodes, and that the 950 nm is the correct one to use with a remote control.<p>I have heard, but not personally seen, that some infrared diodes can be seen by the eye under some conditions. The eye has a very slight tail of response into the infrared. A bright 880 nm diode might be just barely visible.<p>You may have the wrong IR diode to match the remote control receiver. This could shorten your range if there is a filter on the IR receiver.

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Edd
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Re: IR remote circuit running out of steam?!

Post by Edd » Sat Apr 30, 2005 12:06 pm

Oh No!
I have tried my device with only one of the IR LED that did not work, no IR signal sent or the IR LED did not light up!!!
I then put both IR LED back together as before and now nothing. No signal sent and neither IR LED light up.
<p>Were both IR LED leads lifted such that you could have inadvertently reversed polarity connections of one or both LEDS wire leads ? ***<p>Interestingly i put together the LED and resistor that bridges the x2 IR LED and when a IR signal is sent the LED does light up. Meaning that power is getting to the IR LED.
Then, that means all is well on power, incoming signals and drive levels to the LED driver terminus.
Do you think i have burnt out the IR LED's?? Is there any way to check??
Well, looks like those Infineon/Osram IR LED’s are some hefty little puppies and the inherent current limiting resistor inline, as well as the hefty 100 ma spec on your series 3 version of units probably preempts that possibility of damage unless you accidentally got direct across power .
And by ‘de way, those units spectral peak is at 880 nm.
Da Da sheet:
http://www.osram.convergy.de/upload/doc ... sfh487.pdf
As far as their testing, use a DVM’s diode test function or the low ohms scale of a VOM testing in the same manner as you would for a diodes forward and backwards characteristics.
I’m still leaning towards my prior ***comment.
On your LED test light thingy, certainly that must be just a Red LED and a series current limiting resistor, and if you were just taking a shunt test across the storage cap, naturally it will still give an indication after removal of power, all of the time until that cap bleeds down.
I was going to suggest the hanging of a DVM across that storage cap to monitor its voltage retention level while a data stream is applied and see how well the voltage level is maintained. <p>(This option being all dependent, on the initial DVM analysis of the storage capacitors voltage level retention.)
The last thought is the distance required to be covered in your link. If there is too much of a power level depletion on the power supply (a parasitically charged electrolytic) by the IR LED’s 30 ma consumption, you might go the opposite direction and decrease the LED’s power consumption by increasing the series current limiting resistor in stages until that threshold where reliable linking is still being maintained. Thereby the taxing of the
finite power reservoir will be diminished.
Yes, exactly the same weather conditions were experienced….ohhhh… I coulda-woulda-shoulda been a duck …
73's de Edd
[email protected] ..….....(Interstellar~~~~Warp~~~Speed)
[email protected]….......(Firewalled-Spam*Cookies*Crumbs)
:)<p>[ April 30, 2005: Message edited by: Edd Whatley ]</p>

scag
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Re: IR remote circuit running out of steam?!

Post by scag » Sat Apr 30, 2005 1:41 pm

Hi Stephen<p>Ok its good that now i know what type of IR LED i need to have. My IR LED is 880nm i beleive.<p>I have seen on the Maplin website a couple IR LED
that are near to 950nm...
http://www.maplin.co.uk/Module.aspx?Mod ... =&doy=30m4
http://www.maplin.co.uk/Module.aspx?Mod ... &doy=30m4D
Would you say one is better than the other or does it matter. I ask due to even though its available online the shop may not have one of them.<p>I shall purchase this IR LED next week.
Many thanks
Mike ;)

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Re: IR remote circuit running out of steam?!

Post by scag » Sat Apr 30, 2005 1:56 pm

Hi Edd<p>No i am very sure i did not get them reversed. Its a shame i dont have a digital camera as i could show you. I have mounted all the components inside a little box with the IR LED sticking out two holes. As i only unsoldered one IR LED there is only one way of putting it back.<p>Yes having this little 'test thingy' was a releif to see that the whole device is not broken.<p>Yes the 'spectral peak is at 880nm' as after Srtephen pointed it out i looked into it aswell, thank you for the link.<p>Sorry you lost me with DVM's and VOM testing as i am not electronic experienced. But i think what i did was correct, Yes??<p>The distance that i think this device needs to reach is about 6 meters as that is roughly the maximum a couch is away from the TV etc<p>Beleive it the sun did come out later today, sun set from my window was lovely. Tomorrow partner and i are walking down at Pen y Pass. Did you get up on the mountains??<p>Many thanks
Mike ;)

rshayes
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Re: IR remote circuit running out of steam?!

Post by rshayes » Tue May 03, 2005 6:35 am

I would try the LD271. It seems to be desidned for this application, and is in a larger package that is likely to be more rugged mechanically.

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Re: IR remote circuit running out of steam?!

Post by scag » Tue May 03, 2005 8:57 am

Hi Stephen<p>The LD271 was the one that Maplin had, so i bought x2, infact a whole set of components again, this time mounted them all on a PCB board.
Nothing!! Still does not work.
Thats with a double 4700uF capacitor.<p>Do you think i may have damaged my PC's serial port in any way?<p>This is so annoying, as i have had it working for 1.5 days. I need to purchase two of the original IR LED and see if i have blown the first two. Theres no way of testing an IR LED i gather??<p>Any ideas from anyone would so be appreciative.
Many thanks
Mike ;)

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sofaspud
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Re: IR remote circuit running out of steam?!

Post by sofaspud » Tue May 03, 2005 9:37 am

If you don't already own a digital voltmeter, you should put one on your shopping list. An IR LED has a voltage drop like any other diode, and that can be measured with the DVM. Or an IR detector can be bought or built easily. And being able to take voltage measurements of your circuit would make troubleshooting much much easier.
You don't need a fancy meter. I can often get an el cheapo model locally for less than US$5. Makes a handy kitchen drawer tool.

rshayes
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Re: IR remote circuit running out of steam?!

Post by rshayes » Tue May 03, 2005 3:55 pm

Be very careful with the polarity of the LEDs. Reverse bias can blow them very easily. The maximum reverse voltage is usually in the neighborhood of 5 volts, and your circuit can probably exceed that.<p>Polarity markings may be hard to notice. Sometimes there is a flat on one side of the package. If the mold is old, the edges of that flat can be rounded and hard to see.<p>Sometimes one lead is longer. This disappears as soon as you trim the leads for some reason.<p>The diode test on a digital voltmeter may give you a crude test. These apply about 1 ma to the diode and measure the voltage. The maximum voltage is limited, so this is fairly safe. A forward biased LED should read about 1.5 to 2 volts. Some meters limit the voltage to less than this, so you have to know how your individual meter works.<p>The RS-232 port should be fairly resistant to short circuits, but checking the actual output levels wouldn't hurt.

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Re: IR remote circuit running out of steam?!

Post by scag » Fri May 06, 2005 11:39 am

Hi sofaspud<p>Many thanks for the response. Yes i do think if im going to be able to give any actuall information that means something to guys like yourselves i need to buy a DVM (i now know what a DVM is!!). Im off to Liverpool this weekend so shall be buying one.<p>I will do some learning (online tutorials) how to use it, then test my device and post some results. I hope everyone dont mind if i still ask for advice???<p>Stephen, thanks for the info regards to the LED. Will also test the serial port with my soon to be new DVM.<p>Many thanks
Mike ;)

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sofaspud
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Re: IR remote circuit running out of steam?!

Post by sofaspud » Fri May 06, 2005 1:02 pm

A handheld meter is an investment you will never regret. With a little safety in mind (for yourself and the circuit under test) a DVM is a snap to use. And it's handy around the house and car for checking electrical sockets and cords, light bulbs and fuses, etc. in addition to the electronic work. I really suggested it for your benefit, not ours, but once you start taking some measurements of your circuit please let us know what you find.

scag
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Re: IR remote circuit running out of steam?!

Post by scag » Wed May 11, 2005 2:16 pm

Hi All<p>Just a quick update, i did buy a DMM. I bought x2 of the original IR LED and had my device working for an hour, tried the device with only just x1 IR LED. It stopped working!! Even when i put both IR LED back. The DMM gives me reading across every component but no obvious clue (e.g. something stoped working). I then bought again all the componets except the x2 capacitors as Maplin had none in stock. I exchanged each component in the device with its new equivelent, plugged it into the PC to test.... Nothing!!!<p>You can imagine this is very annoying, stronger words have been said :) <p>I will attempt to give some DMM readings and hope with your help i might get an idea why.<p>I will be buying x2 more capacitors just incase.
Stay tuned
many thanks
Mike ;)

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sofaspud
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Re: IR remote circuit running out of steam?!

Post by sofaspud » Wed May 11, 2005 2:55 pm

Let us know what transistors you are using, and also what diodes (D1 & D2, and the ones just marked "silicon").

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Re: IR remote circuit running out of steam?!

Post by scag » Sat May 14, 2005 8:40 am

Hi Sofaspud<p>many thanks for the support<p>Ok the components...
NPN (QR40 2N3904) (http://www.maplin.co.uk/Mproduct.asp?oc=QR40T)
PNP (QR42 2N3906) (http://www.maplin.co.uk/Mproduct.asp?oc=QR42V)
D1 & D2 (QL79 1N4007) (http://www.maplin.co.uk/Mproduct.asp?oc=QL79L)
Silicon diodes (QL80 1N4148) (http://www.maplin.co.uk/Mproduct.asp?oc=QL80B)
1K (M1K Min Res 1K)
2.2K (M2K2 Min Res 2K2)
10K (M10K Min Res 10K)
3.9K (M3K9 Min Res 3K9)
22Ohm (M22R Min Res 22R)
IR LED (CY88 SFH487-3) (http://www.maplin.co.uk/Mproduct.asp?oc=CY88V)
4700 uF (VH57 PC Elect 4700uF 16V) (http://www.maplin.co.uk/Mproduct.asp?oc=VH57M)<p>Ok here are some figure, that i hope makes sense.<p>I have the DMM on and switched to 20K in the Ohm section.
I plug the black lead into the COM socket on the DMM.
I plug the red lead into the V(Ohm)mA socket on the DMM.
I touch the black lead to the GND wire (green) and the red lead to the TXD (blue)
The reading i get is -13.82<p>I have the device pluged into COM1.
I place both the black and red leads to the same points as before and i get the reading of -13.82<p>I unplug the device from COM1. Placing the black and red leads at the same point the DMM counts up from minus figures to zero. (I gather this is the capacitor charging up taking power from the DMM??)<p>I try these stpes again but taking the readings from COM2. The readings are -13.79<p>What readings should i take next???<p>Many thanks
Mike :)

scag
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Re: IR remote circuit running out of steam?!

Post by scag » Sat May 14, 2005 8:57 am

Ok the x2 IR LEDs
The IR LED (that is nearest to the PNP) has the long leg towards the PNP the short towards the next IR LED. The second IR LED has its long leg towards the first IR LED and the short leg towards the bottom line (??? hope that makes sense)<p>I turn the DMM dial towards the diode setting as per instructions that came with the DMM.
I place the black lead on the first IR LED long leg and the red lead on the first IR LED short leg. The reading i get is 1.804 I place the same coloured leads on the same length legs of the second IR LED and the reading i get is 1.776<p>I then take a reading for each IR LED when a signal is supposed to be sent but the readings do not change???<p>Mike ;)

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