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Old Jan 14, 2003, 10:20 PM
rebmeM roineS
MrBungle's Avatar
Rockingham, Perth - Western Australia
Joined Apr 2001
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Hi guys,
I've been designing and playing around with a very simple circuit for an IR Tx.
Like Koichi's circuit, this one plugs into the 'buddy' socket on a standard rf Tx.
But instead of a PIC, I'm using a 555 timer IC to generate the 38khz sub-carrier, and modulating this with the output from the Tx. This is not only cheaper, but allows the PIC to be used to make another receiver
I'm happy with its operation, the 38khz sub-carrier remains stable even when the battery voltage of the Tx drops to around 6 volts, theres very little frequency drift.

At this stage the 38khz sub-carrier is set at 50% duty cycle and my current limiting resistor for the LED is set for 20mA, so average current is only 10mA.
The LEDs I'm using can handle 1A currents at 10% duty cycle, so my next step is to experiment with lower duty cycles while monitoring the IR sensors ability to detect with lower duty cycles. I'm also going to watch what effect this reduced duty cycle has on interference from other light sources, if any.

At the moment I'm only using a single IR LED, so range is limited to a few metres, but when everything has been sorted I will be using many more. The circuit only uses 8 components without LEDs.

One thing I found interesting, my (very OLD -- lost the datasheet many years ago) IR sensor inverts the output! This was easily fixed at the Tx (modulate the spaces), but it got me wondering just how many different sensors have different outputs? hmmm

More later.

Simon
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Old Jan 15, 2003, 08:29 AM
Registered User
Peotone,Il USA
Joined Oct 2000
100 Posts
Andy
Koichi

Does the radio decoder code from your site decode to
standard servo outputs or is it able to drive actuators
direct? Has anyone been able to use Koichi's code?
I would like lower weight and size by being able to
eleminate the servo decoder chip entirely.
Ive been experimenting using a servo decoder chip
from a old RF receiver (APEX)followed by actuator driver
chips from JMP.

THANKS
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Old Jan 15, 2003, 10:56 AM
Thats NOT indestructible
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London UK
Joined Apr 2002
1,448 Posts
Mr B

How exactly did you wire up the 555......sounds EASY

Josh
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Old Jan 15, 2003, 11:47 AM
rebmeM roineS
MrBungle's Avatar
Rockingham, Perth - Western Australia
Joined Apr 2001
615 Posts
Hi Josh

The 555 is hooked up as an Astable Multivibrator, this config is shown in most, if not all datasheets for the 555.
Formula for component values are given also.
When I'm done playing around and I'm 100% satisfied with the circuit operation, I'll draw up a schematic.


If you can't wait 'till then and want to tinker, I have a few tips to steer you away from trouble. Let me know if you need any help.

Simon
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Old Jan 17, 2003, 08:20 AM
Registered User
Peotone,Il USA
Joined Oct 2000
100 Posts
Need help
I built up test transmitter based on a 555 chip with 9 LEDS
For my receiver i'm using a Vishay TSOP4840 driving a
servo decoder chip, everything works fine but need to
range test in gym tomorrow. I know from reading post here
that for the system to be effective it will require more LEDS.
Now for the hard part.
I've built up a PIC programmer and down loaded software
with the help of people here in order to construct a
receiver similar to the one by Koihci.
However after looking over his web site I have no idea on
using the codes posted on his site in a format that can be
loaded into the 12c509 using IC-PROG. Would one of you
knowledgeable gentleman please provide me PIC code his
or yours in a useable form?
thanks
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Old Jan 18, 2003, 12:17 PM
rebmeM roineS
MrBungle's Avatar
Rockingham, Perth - Western Australia
Joined Apr 2001
615 Posts
Joe,
You need the CC5X compiler for the rxdecode.c file.
Its available here: http://www.bknd.com/cc5x/index.shtml

OR

I have compiled it and its available here for download as a .hex file, which will work with IC-prog.
rxdecode.hexNo longer available from me, see EDIT below.
(right click the link and select 'save target as')

I have not had a chance to test it yet, but its compiled straight from Andy's .c file so should work.
Jochen made a few few changes to the code he's running, maybe he can supply you with a tested .hex file.

Happy Pic'n

Simon

EDIT: Andy now has the Hex file available from his site:
http://www.gaspode.co.uk/planes/radio/radio.htm
No longer available from me.
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Old Jan 18, 2003, 12:25 PM
Thats NOT indestructible
j8m8l's Avatar
London UK
Joined Apr 2002
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Mr B

I believe that you have used the poptronics programmer

Would you reccomend it for this stuff?

I would rather get that then make one from scratch for now......and the price would probably be close

Later

Josh
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Old Jan 18, 2003, 02:55 PM
Registered User
Peotone,Il USA
Joined Oct 2000
100 Posts
Thank you Simon
I've ordered some 12c509's along with a EPROM
version for testing.

Josh
Do you still need a transmitter schematic for
using a 555 chip? I have one that I could scan in,
i'm using 40 Khz instead of 38.
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Old Jan 18, 2003, 03:45 PM
Thats NOT indestructible
j8m8l's Avatar
London UK
Joined Apr 2002
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DUDE

I would love it

Do you change the modulation by altering like a resistor or something

Thanks

Josh
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Old Jan 18, 2003, 06:43 PM
Registered User
Peotone,Il USA
Joined Oct 2000
100 Posts
Josh,
I have a system patterned after info on Koichi's
web site. Im using a old Futaba RC transmitter with the rf module removed, the IR module plugs into the trainer jack for power and pulse train.
the pulses need to be inverted so that only the spaces are transmitted at 40Khz.
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Old Jan 19, 2003, 04:25 AM
Thats NOT indestructible
j8m8l's Avatar
London UK
Joined Apr 2002
1,448 Posts
Cool Joe

Guys

I am setting up a indoor rc website at the mo, and it should be up within the next month or so

It will have info on indoor and parkflight, and stuff about chargers etc too, as well as a forum, (with sections for all the UK guys ) which i am working on it right now

Would you like me to have a go compiling a simple page, with all the info required to make one of these IR setups, including code, programmers etc?

Unfortunatly, it will be a while before i can do it (like a month or so) as i have exams coming up soon....and i have done no work yet

Later

Josh
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Old Jan 19, 2003, 06:54 PM
Registered User
Peotone,Il USA
Joined Oct 2000
100 Posts
Simon,
Do you know if Koichi has codes for the ESC on
his site? Do you think there is any advantage using emitters with wide angle (150 deg) over a
large number of less directional ones?

Tnx
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Old Jan 20, 2003, 05:15 AM
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Japan
Joined Dec 2002
327 Posts
The HEX file for PIC 12C509A of an infrared receiver and a speed controller(ESC) was exhibited.

However, it is a Futaba format.

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Old Jan 22, 2003, 12:05 AM
rebmeM roineS
MrBungle's Avatar
Rockingham, Perth - Western Australia
Joined Apr 2001
615 Posts
Quote:
Originally posted by j8m8l
Mr B
I believe that you have used the poptronics programmer
Would you reccomend it for this stuff?
Hi Josh,

The Poptronics programmer is a JDM design, just in kit form.
I built mine from the Poptronics diagram, not the kit, and had to change a capacitor value to get it working. Then I discovered the JDM site and saw that he had originally designed it with the same value capacitor I was using, I dunno why Poptronics changed the value.

The programmer works fine with everything I've thrown at it, It even works with 12CE50x chips. (eeprom version of 12C50x)

If you get the Poptronics kit, and it comes with a 10uF electro.(from memory) and won't program but reads ok, substitute it with a 100uF electro. Leave the 22uF cap there.
I think the kit comes with the dos software, I used this for a year or so without problems, but then changed to IC-Prog for windows, much easier to use.

I'm not done playing around with the 555 yet, looks like Joe has done something very similar.
Yes the modulation frequency is set by 2 resistors and one cap, but once set on a value for the cap, R2 basically sets frequency and R1 sets dutycycle. From datasheets I've looked at, most IR sensors will de-mod anything close to 38khz, for example, Sharp's IS1U60 sensor will accept anything between 36 to 41khz, so frequency doesn't seem to be very critical.

Simon

Correction: 12CE50x should read 12CE51x
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Old Jan 22, 2003, 12:21 AM
rebmeM roineS
MrBungle's Avatar
Rockingham, Perth - Western Australia
Joined Apr 2001
615 Posts
Quote:
Originally posted by joe price
Simon,
Do you know if Koichi has codes for the ESC on
his site? Do you think there is any advantage using emitters with wide angle (150 deg) over a
large number of less directional ones?

Tnx
Hi Joe,
Looks like he does

I really don't know, but I can't think of any reason that wide angle emitters would offer any advantages over narrow.
Given two diodes with the same power output, the wide angle output is spread over a larger area, but with less intensity, therefore you will need more of them to get more range.
But the narrow one would have high intensity but not the spread so more are needed to get coverage.
Looks like it would be 12 of one or a dozen of the other to me.

Simon
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