Author Topic: ADMIN HELP! PHOTOCELL/photoresistors  (Read 3214 times)

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Offline knightimerTopic starter

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ADMIN HELP! PHOTOCELL/photoresistors
« on: August 23, 2007, 04:21:34 AM »
heys, i was wondering wat photoresistors are for! and if they are nessescary for your $50 robot? and i was wondering about, why not just normal resistors? like the one on the microcontroller?

please & thanks

Offline Admin

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Re: ADMIN HELP! PHOTOCELL/photoresistors
« Reply #1 on: August 23, 2007, 01:24:09 PM »
http://www.societyofrobots.com/schematics_photoresistor.shtml

(no need to write Admin in the subject line, there are many other people that can help :P)

Offline HDL_CinC_Dragon

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Re: ADMIN HELP! PHOTOCELL/photoresistors
« Reply #2 on: August 23, 2007, 01:25:52 PM »
the photo resistors react to light. depending on the amount of resistance, the bot can make a decision about whats in front of it. A regular resistor will always have about the same resistance all the time
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Offline knightimerTopic starter

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Re: ADMIN HELP! PHOTOCELL/photoresistors
« Reply #3 on: August 24, 2007, 08:57:07 PM »
um, i still dont get what photoresistors are FOR, you only told me what they can do? no wait...ok. "What are photoresistors used for in a robot?, do they alter resistance or something?"

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Re: ADMIN HELP! PHOTOCELL/photoresistors
« Reply #4 on: August 24, 2007, 09:35:52 PM »
They can sense light. Its like an eyeball, but for a robot.

Offline HDL_CinC_Dragon

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Re: ADMIN HELP! PHOTOCELL/photoresistors
« Reply #5 on: August 25, 2007, 12:28:25 AM »
Sorry knight

When light shines upon the photoresistors (AKA photocells), the resistance goes down letting more voltage through. The more light, the less resistance, the darker it is, the more resistance.

When the $50 robot approaches and object, it will see that it has gotten slightly darker because suddenly the resistance has increased and will then move away from that spot.

Hope this helped!
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Offline knightimerTopic starter

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Re: ADMIN HELP! PHOTOCELL/photoresistors
« Reply #6 on: August 26, 2007, 04:20:19 AM »
hey thanks, it DID help so well done! But what if i dont want the $50 robot to steer away from darkness? i want the robot to 'chase my cat' (like how one famous robot builder said), or follow an object, or steer away from objects? how do i do that and, if i want to do this, do i really need photocells/photoresistors?

and quick questions about the servo:

firstly, i dont understand admin's tutorial for modifying the servo, even though i want to/need to, can you link me or help me with modifying? the tutorial is too confusing. And seconly, your hex code for 0 degrees, where do you put it, etc???!! VERY CONFUSED! thanks!

BUT! the remote control robot! can i use any receiver? and where do i connect it on the microcontroller?, also, the $50 tutorial, you said in yur parts list, 2- 0.1uf capacitors, where did you put the other one? and the 36 position breakaway male header, you listed 2 of them?

Also, the 5 pack 340ohm & 1.62ohm resistors and 5 pack Cds photoresistors, if i cant find 5 pack ones, what should i get instead? and how many of each?? because i can only buy the individual ones....

the breadboard!, not the pc board, the bread, um theres a metal platform at the back, how do you connect the wires and LED leads or the resistor leads? just wondering with a breadboard. and the batteries, can i use energizer batteries or duracell batteries aslong as they are the same volts?


THANKS THANKS THANKS! alot! and....HELP HELP HELP  ??? ??? :-\

Offline knightimerTopic starter

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Re: ADMIN HELP! PHOTOCELL/photoresistors
« Reply #7 on: August 26, 2007, 04:30:20 AM »
oH!! i forgot, this is out of the subject but: Whats a CNC?, btw if you didnt get it from the previous reply, I NO WHAT PHOTOCELLS ARE NOW! thnX! and help!

Offline hazzer123

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Re: ADMIN HELP! PHOTOCELL/photoresistors
« Reply #8 on: August 26, 2007, 05:55:09 AM »
CNC stands for computer numerically controlled. I think its the name for a machine which is controlled directly from a computer.

Most machines with this type of control are milling machines/ laser cutters/engravers, etc.
Imperial College Robotics Society
www.icrobotics.co.uk

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Re: ADMIN HELP! PHOTOCELL/photoresistors
« Reply #9 on: August 26, 2007, 09:06:28 AM »
Quote
hey thanks, it DID help so well done! But what if i dont want the $50 robot to steer away from darkness? i want the robot to 'chase my cat' (like how one famous robot builder said), or follow an object, or steer away from objects? how do i do that and, if i want to do this, do i really need photocells/photoresistors?

I recommend just keeping it simple and getting the photovore to work. If you want a photophobe (run away from light), just reverse where you plugged in the photoresistors.
http://www.societyofrobots.com/programming_photoresistor.shtml

After this, we can help you on your next project . . . like this:
http://www.societyofrobots.com/robot_50_robot_sharpIR.shtml

Quote
firstly, i dont understand admin's tutorial for modifying the servo, even though i want to/need to, can you link me or help me with modifying? the tutorial is too confusing. And seconly, your hex code for 0 degrees, where do you put it, etc???!! VERY CONFUSED! thanks!

Which part did you get stuck at?

Quote
the remote control robot! can i use any receiver? and where do i connect it on the microcontroller?

Why would you like the remote to connect to your microcontroller? (so that I can better help you)

Quote
also, the $50 tutorial, you said in yur parts list, 2- 0.1uf capacitors, where did you put the other one?

hmmmm good question . . . ignore the other . . . never noticed that mistake . . .

Quote
and the 36 position breakaway male header, you listed 2 of them?

dont worry about this, you will end up using 75% of them. or 100% if you use all the features of the ATmega8 . . .

Quote
the breadboard!, not the pc board, the bread, um theres a metal platform at the back, how do you connect the wires and LED leads or the resistor leads? just wondering with a breadboard.

http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=DGUS,DGUS:2006-11,DGUS:en&q=how+to+use+a+breadboard+tutorial

Quote
and the batteries, can i use energizer batteries or duracell batteries aslong as they are the same volts?

what do the batteries power? you might do better getting NiMH type batteries:
http://www.societyofrobots.com/batteries.shtml

Offline knightimerTopic starter

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Re: ADMIN HELP! PHOTOCELL/photoresistors
« Reply #10 on: August 28, 2007, 05:58:40 AM »
um, ok the servo, i get it now, sorry guys, i read other various posts and get what to do now! thanks anyways!!!!

about the rc, i want to make it rc control? because it would be awsome if i can, and i'd like to drive it around the house for fun too! and also, i'd like to asK:

"What happens if you add a IR Rangefinder and rc control together, would it work or mash up together badly? i'd like mine to have both? if its possible, one time to maybe drive it around, and one time to let it roam around..=] you know?" THANKS

oh yeh, are there any brands for NiMH batteries?

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Re: ADMIN HELP! PHOTOCELL/photoresistors
« Reply #11 on: September 14, 2007, 06:53:03 AM »
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What happens if you add a IR Rangefinder and rc control together

its possible to do both . . . you would need a microcontroller, and a program to decide which to use and how. for example, you can RC your robot wherever you want, but when the scanner detects a wall it wont let it drive into that wall. etc.

you would need to attach your RC receiver output to a microcontroller. its described in the RC tutorial:
http://www.societyofrobots.com/remote_control_robot.shtml

 


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