Laser Sensor button?

[Drew]

**not an electrician**

Does a light dependant resistor work the other way?

Put your finger over the light reciever and see if it stops the flow.

I could be wrong...

[DaveW]

+Rep for Guttenaffe and Airbozo, great information!

-Dave

[Spacehonkey]

Would a wall wart work? 15 buck at the most at your local wally world.

Wal-Mart $15, ummm, didn't think they carried stuff like that. I'll have to give them a shot. I'll go run down to the nearest one after I get off work today.

**not an electrician**

Does a light dependant resistor work the other way?

Put your finger over the light reciever and see if it stops the flow.

I could be wrong...

I thought that would work too but it didn't change anything. I think I'm going to try and surf the web today, if I have any free time, and see what kind of info I can find.

+Rep for Guttenaffe and Airbozo, great information!

-Dave

Ohhh yeah, how could I of been so forgetful. +Rep to Gut & Air for the helpful info. Sry I didn't give it to you guys earlier.

[Spacehonkey]

OK I'm a complete retard. Ignore the part in my last post about not getting the LDR to work.

I made a 12Vdc pwr supply out of a 9V & 2 AAA batteries. I wired it like this, just to see if it'll work.

+-----resistor-----LDR-----resistor-----LED------

Now whenever I put my finger over the LDR the LED dims. Now the next step is where I get all mixed up in the head. Now the next step would be to wire in the relay but I'm doing something completely wrong because nothing works now. I'm not sure I have a complete understanding of all the wiring. I didn't think this would confuse me but I've never really worked with circuit boards before. I know I had to of wired it up wrong. I'll play around with it this weekend and see it I can figure it out.

[armadilloben]

You could do this with a led and a photo voltaic sensor (a light sensor) and a small relay circuit. Finger breaks the beam, relay makes contact...


EDIT: Exactly like the sensors that go off when you enter a store. Break the light beam, bell rings...

EDIT2: Similar to this circuit although it is just a light sensor circuit;
http://www.uoguelph.ca/~antoon/circ/sensor2.htm

EDIT3: More info here (some info that just6 does not apply too);
http://ourworld.compuserve.com/homep...epage.htm#menu

EDIT4: and even more;
http://home.cogeco.ca/~rpaisley4/PhotoDetectors.html

smart idea man but i think that it may be cheaper for him to use a Photoresisitor its basicly the same thing but he could have it light or dark activiated so he could like just wave his finger over it and it could interupt the circut and turn the pc on... i think

[Spacehonkey]

Just a quick update. Since this laser switch problem I'm having is a circuit problem and not so much a modding issue, even though once I figure it out it will be used on a future mod of mine, I've asked for help on a circuit board forum. Whenever I fix this I'll post back here with an update. Thx for all the help guys.

[DevilTeck]

Just a quick update. Since this laser switch problem I'm having is a circuit problem and not so much a modding issue, even though once I figure it out it will be used on a future mod of mine, I've asked for help on a circuit board forum. Whenever I fix this I'll post back here with an update. Thx for all the help guys.

Spacehonkey,
really good idea, let me see i can illuminate the situation(every pun intended ) in a series circuit(which you have) resistors restrict or limit the flow of current in the circuit, now a LDR has a very high resistence when dark(usually 100k ohms or higher) which will cut most of the current to the circuit. Now when light illuminates them there resistance is dropped to near zero allowing current to flow. Hope this helps. also check this out http://www.technologystudent.com/elec1/ldr1.htm

[Spacehonkey]

Thx for the info, DevilTeck. My current problem isn't with the LDR, that works just fine now. I just didn't understand how they worked when I first started this project but now with the help of people like yourself I'm just a little bit smarter with this stuff. My problem now is the LDR isn't influencing the output voltage from the OpAmp which should control the transistor which in turn engerizes/deengerizes the relay.

[Spacehonkey]

I finally got the whole thing to work. I was using the wrong transistor the whole time. I was using a PNP when I should have been using NPN. Now the whole thing works great. I need to buy a new circuit board since the one I was using has a ton of solder all over it. Hopefully by the end of the week I'll have the circuit card built up and then I'll use an old computer a friend just gave me last week to see if this will work like I intended.

[Spacehonkey]

Anyone here know how to make a PCB design out of a wire schemetic?