Laser alarm schematic - noob questions

I, admittedly, am terrible with elecronics. I have never done them before, and although I took some rudimentary electronic classes in high school (basically learning Ohm's law, that's it...) - I have never built a circuit before.

But I am trying to follow the directions to make this circuit which are plans for a diy laser alarm system that I would like to incorporate into a game I am making.

The schematic is:



I have all the parts, except for the 5K variable resistor - so I substituted a 10K variable resistor (not sure if that would work, but it was only a $1 or so...)

Anyway, I realized, as I put this together, that I had no idea what direction to make this circuit. In other words, while I understood what the base, collector and emitter were on the transistor, I didn't know what side to solder to what for the other components. For example, what direction does the capacitor go? (What side is soldered to what?) In addition, how do I solder the variable resistor into this whole mess? What gets soldered to what pin? (Assuming that the 10K variable resistor will work, the resistor I have has three pins, and a small slotted dial on the end for changing the resistance).

Also, I have two components, the battery holder and the siren with red and black wires. How do the colored wires get worked into this (In other words, how do they get connected?)

Any help would be appreciated!

Post edited by: Etienne_72772, at: 2008/07/16 17:10

Etienne_72772, welcome to the forum, I hope you will find it useful

I honestly must admit that I have totally no experience with these kinds of electronics so I will up this thread for it to stay in view and have members see it in order that they can give you advise.

My apologies and good luck

hi laser man, i think ihave some snswers 4 u.the base, collector and emitter of the transistor can be found esilly from electronics data books.as of the variable resistor,a 10K will work fine and u can connect the center terminal and one end teminal together then u can consider the connected terminals as one and the other end terminal as the second one.and good luck.

I don't know if you are still looking but I have included a marked up schematic that should help. (Do not spell polarized that way though.)

Hey man don't you think that the alarm will automatically go off as soon the person passes the laser n once again it is pointed to da photo cell.....
and what's the use of the variable resistor n the diode