DIY Virtual Walls??

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Re: DIY Virtual Walls??

Postby glnc222 » August 3rd, 2016, 1:34 am

I had a TV integrated remote receiver IC from Radio Shack which detected a Roomba Virtual Wall and also a keychain TV remote, so how can the frequency be different? I think it is specified for the 38khz standard. In the Neato Optical Boundary thread and related included links. There are a few different standards in use, seemed to match here.
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Re: DIY Virtual Walls??

Postby keys » August 24th, 2016, 6:43 pm

pccox32 wrote:I am a complete newbie to this. I am planning on teaching myself to solder. I am going to go buy everything in order to make this virtual wall.

Can someone please provide me a list of everything I need in order to create this virtual wall


From noob to fellow noob, have you read this entire thread? Some folks don't respond to the "I'm a baby bird please feed me" posts. You will get a lot more respect once they see you have done your homework. Please don't take offense to this, as I am merely trying to help. If you haven't take the time and read this entire post. Happy Hacking.
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Re: DIY Virtual Walls??

Postby glnc222 » August 24th, 2016, 7:21 pm

Guide to introductory electronics and microcontroller material was supplied privately not to clutter or duplicate web tutorials. There are both Arduino as well as PIC virtual wall replacements. PIC's require commercial programming hardware and software tools, but allow more compact specialized projects. Arduino's offer simplified programming tools for beginners, free software. Request the PM's privately if wanted.

PIC Microcontroller resources
Various size controllers, smallest only $1. Programming boards to flash under $10.
http://www.ebay.com/itm/PIC-USB-Automatic-Programming-Develop-Microcontroller-Programmer-K150-NEW-/321683946977?hash=item4ae5db7de1:g:GvoAAOSwEK9T2KJR
Free PC development software e.g.
http://www.opensourcepic.com/IDE.php (Linux)
http://pic-microcontroller.com/download-mplab-ide/ (Windows)

Arduino has various ready made application attachment boards, sensors etc., "shields", while the PIC is more compact for custom made applications, with separate flashing "programmer" boards to install programs in the controller, moved to a DIP socket on the project board.
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Re: DIY Virtual Walls??

Postby microflite » September 8th, 2016, 1:48 pm

Can someone post the schematic image please? The original ones aren't accessible any more.

Thanks!
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Re: DIY Virtual Walls??

Postby microflite » September 8th, 2016, 1:50 pm

Oh sorry. I do see the rj555' schematic someone reposted.

This forum is a great resource. Thanks, all!

Ashok
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Re: DIY Virtual Walls??

Postby alaskaboy » October 31st, 2017, 3:31 am

Hi,
Is it possible to change rj555's schematic to support 3V operation?
Then we can use rechargeable battery for this virtual wall.
Thanks
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Re: DIY Virtual Walls??

Postby glnc222 » October 31st, 2017, 12:12 pm

I do not know about rj555's version but a 38khz signal which may operate Roomba receivers has often been made of 555 oscillator IC's, e.g. https://electrosome.com/ir-transmitter-receiver-led-tsop1738/ and other examples on the web.
The Texas Instrument CMOS version TLC555 http://www.ti.com/lit/ds/symlink/tlc555.pdf at least specifies power supply as low as 2v, suitable for 3v battery packs. It sinks almost 1/4 amp output requiring no transistor to power an emitter LED. A 16.5K ohm resistor R2 in that example produced close to 38khz (20K and 100K in parallel, or 15K and a 5K 15 turn trimmer in series for tuning). The difference between say a 5v and 3v supply would be in the current limiting resistor for the emitter LED, which has around a 1v voltage drop. Subtract the 1v from the power supply voltage, divide by the current wanted through the LED, to get the resistor required.

For battery operation the power consumption can be reduced with a second 555 to power the first, through the ground supply. A low frequency burst pattern can be made instead of running the LED continuously at 38khz.
[edit] There is probably some connection to the first 555 besides power which could stop it, but I would have to research that; probably preferred. Actually, grounding the junction of C2,R2 with the output of the second probably would suffice. Test on breadboard; stopping is one thing, restarting another. [correction C2,R2 -- when starting to charge C2 is at ground, so safe -- don't short an output]. But see whether stopped off as desired instead of on.

Roomba Virtual Walls were found to be received by Vishay TSOP TV remote signal receivers, which are also what these 555 projects are made to operate, suggesting they will also operate Roomba bots. Such signals can also be generated by a cheap key chain TV remote with a button wired closed for repeated signals; see Neato forum thread http://www.robotreviews.com/chat/viewtopic.php?f=20&t=17083&p=122716&hilit=optical+boundary#p122716.
It would be easy to check whether a TV remote on hand causes any response in a Roomba bot.

I would have to test but the timing resistor values might also have to be changed for lower voltage. The 555 frequency formula does not mention the supply voltage. This could be from internal voltage references independent of supply voltage, common in certain comparator components.

[edit] Example of a high power 38khz focused 20 degree emitter; the hot current limiting resistor must be ventilated. Receivable by Vishay TSOP4838 TV remote sensors outputting constant logic low or however modulated.
Image
Image

[edit] for power more typical of Roomba VW's, a single LED can be driven directly by the 555, with no transistor, on the negative, ground LED line. TLC555 version supposedly sinks over 200ma, but might need a higher voltage than 5v power for the highest amounts, while the high level drive is limited (but enough above to switch a transistor).
Smaller transistors such as BC547 can drive up to 100ma on low voltage.
Last edited by glnc222 on November 9th, 2017, 12:09 am, edited 3 times in total.
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Re: DIY Virtual Walls??

Postby glnc222 » October 31st, 2017, 2:30 pm

If you are in the U.S. and making a DIY virtual wall, you might use for a housing the Samsung Virtual Guard I am discarding, no charge, leave an address Private Message. Houses two D cells or smaller, discard the top electronics. See other thread here.
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Re: DIY Virtual Walls??

Postby glnc222 » November 4th, 2017, 6:17 pm

IR Control Basics

An explanation of many technical aspects of IR communication are given in this Application Note AN1016-D from mfg.s
https://www.onsemi.com/pub/Collateral/AN1016-D.PDF

Interesting receivers use Photo Diodes not Transistors for high frequency use like TV remotes, 38khz.
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