DIY Virtual Walls??

[el duderino]

Anyone know a cheaper way to make some VW's?

[Talon]

Anyone know a cheaper way to make some VW's?

Sure.........I just use a case or two of pop or beer bottles to block off an area that I don't want the Roomba to go into It's "cheap" >>>>>>>>>>>>>>>>Talon

[rj5555]

Yes, I made some already (About $ 2,- worth of components + a power supply or battery). I will try to find the schematic and post it.

[rj5555]

Found it;

[rj5555]

Note that the values of R1 and R2 may need a slight adjustment.
I have the best results with R1 = 22K and R2 = 220 Ohm
I also made a working version with less parts, see schematic below

[rj5555]

[curtiscr1]

A couple of questions about the circuit.

1. I assume the IC is being used as an oscillator? What frequency does it run at and is this critical at all? My guess is that that turning the IR led on and off just saves battery life, right? I've got a bunch of PICs lying around that could make just about any frequency up to 100khz or so.

2. Does the Roomba transmit any signals (such as the IR cliff detect signal) that could be detected by a new virtual wall unit? If so, an IR detector added to the PIC might be able to turn on the virtual wall only when it sees Roomba driving by.

I know the battery savings wouldn't be much, but heck, that's the fun of this type of hack.

[rj5555]

1) The virtual beam is a 500Hz pulse modulated on a 35Khz carrier pulse. The 35Khz is needed so the sensor on top of the roomba detects the signal and is rather critical if you want a good range. The 500Hz is less critical.
So no you can't oscilate on 100Khz it won't work.

2) Yes the Roomba is transmitting ir signals (wall following sensor and cliff sensors) but the will be difficult to detect (weak signal and directed the 'wrong' way) I'm not sure how much current a PIC uses but I think it will consume more battery looking for the Roomba than the IR circuit does by just pulsing the LED.

[dave w]

rj5555
Probably too late to get a response on this old thread...but,

On a VW unit, what is the top mounted IR (transmitter/receiver?) doing?
Not logical that it is transmitting the "avoid me" signal.

Thanks!!

Dave

[Gordon]

On a VW unit, what is the top mounted IR (transmitter...) doing?

It is emitting the same IR wavetrain as the main beam. Both LEDs are fed with the same signal. The top-emitter runs at constant level.

[rj5555]

rj5555
Probably too late to get a response on this old thread...but,

On a VW unit, what is the top mounted IR (transmitter/receiver?) doing?
Not logical that it is transmitting the "avoid me" signal.

Thanks!!

Dave

yes its only a avoid me signal.
It sends a weak virtual wall signal 360 degrees around the device. this sho the roomba cannot push it away when it would come from behind

[dave w]

Thanks Gordon and rj5555!

Oh, gee, what a bozo.

Because of the way we use VWs, I never considered Roomba coming up behind a VW. Yes the 360 degree now makes total sense.

Sorry, the brain juice must be beginning to evaporate.

[bigbang]

Hi,

Apologies for being a lame newbie but I am really interested in putting one of these together. I am not really very familiar with circuit diagrams and components but I want to hack this together on a breadboard to see if I can get it to work.

I have sourced all the components in the second diagram above except for one, the IC1P component. What exactly is this component? Is there a component number I should be looking for?

Again, apologies for being extremely clueless and thank you for posting the circuit diagram.

[bigbang]

Is there no-one out there who can help me? All I want to know is what the IC1P component actually is, I don't recognise its circuit diagram symbol and since there is no part number it's very difficult for me to work it out...

[foongpl]

Is there no-one out there who can help me? All I want to know is what the IC1P component actually is, I don't recognise its circuit diagram symbol and since there is no part number it's very difficult for me to work it out...

IC1a,b,c,d..p are in One physical chip, the 4093. If I am not mistaken, it is a Quad Schmidt-Trigger NAND Gate CMOS 14pin chip.
The IC1P icon, just shows where you should wire the power supply pins for the whole Chip (pin 7 and 14).

[bigbang]

Thank you very much!!

[krt7]

I've built the circuit from the second schematic, though I had to change C2 to .05 uF. Originally the carrier frequency was around 17kHz, and with that modification it's about 30.5kHz. Also I didn't find the BC547 so I have substituted a 2N2222 transistor.

I get about a 4 foot range of operation. What range should I expect?

Any idea if it's my IR LED, the substituted transistor, or the frequency that is limiting my range?

[ksem]

is it critical to have near +5v on the power source for this circuit, or would a 6v or higher supply work for it? What are you guys mostly powering this with? Wall warts with or without regulators? Batteries? etc.

[krt7]

I'm using a 5v regulated wall-wart.

If you choose batteries, I'd recommend adding a regulator. The supply voltage will affect the frequency of both oscillators.

As for 5v vs. 6v, you should be able to adapt the RC values (as well as the dropping resistor for the LED) to any higher voltage up to whatever the maximum is for the 4093. 18V, I think.

[sandman207]

krt7-

Sorry to bug you, but I was wondering if you had any schematics of your version. I'm trying to track down all the parts locally and I'm having difficulty with the resistors. Any help would be greatly appreicated!

Thanks