japroach

It sounds like you are describing the 4 pin molex connector. The two black wires in the middle are ground, and you should read voltages with your negative lead connected to them. The negative voltages supplied by your power supply are -5 and -12V, and they will connect to your motherboard only. All the grounds are connected together, and the negative and positive voltages are referenced from them.

http://computer.howstuffworks.com/boolean3.htm

Just get an adjustable one they are maybe 20-40$.. Or you can use a light dimmer to reduce the power going into your soldering iron. I set a fan next to where Im working, if I dont the fumes rise straight into my mouth and eyes. Open any windows and doors in the room as well.

Yeah there are no connections on the board, those are just places to solder your component leads. What you do is place the two wires in two holes close to each other, and make a solder bridge, or just bend one of the wires over a little to make it easier. And if they arent close then you can use some wire on top of the board to connect two points. Here is the only decent example picture I could find: I think the only reason hes using the large copper wires below is the power in the circuit. Not needed on normal boards. btw I use these boards a lot, its very easy to wire up a schematic.

I dont think thats what hes asking. What hes saying is why use a LED driver chip. Main reason is to have constant current output to a bunch of LEDs. Most of it explained here: http://www.siliconchip.com.au/cms/A_100966/article.html

For a transistor you can get a curve tracer that will give you a lot of info. For a capacitor/inductor/etc you have to use a freq and check its response at that freq. or do a sweep or something. The problem is interfacing with the computer. There is a box you can build to measure inductance, capacitance, and freq sweeps of a speaker. But Im not sure if you can import all this info into the circuit simulator. Sure you can put in transistor gain and diode drop (probably), but not everything. Good idea though.

Did you check if theres a fuse inside that you can replace?

"The third problem is about the AND-GATE because as soon as I remove the magnets the logic would go to 0 (0v) and I would not have enough time to open the door." flip-flop that is reset when the door is opened. Or it can be reset once your timer has timed out (count-down is activated by the smart card).

http://www.poweredparaglidingontario.com/news/caps_lock.JPG www.google.com

Yeah I agree.. in the future you make be making parts decisions for your company. And if they have been kind to you in the past, you tend to favor them.. :) btw National stopped sending samples to all free/ISP/and school emails that I have. I would gladly pay the shipping, but they want shipping for EACH IC sample.. so thats like 16$ if I want some + and - regulators or something... btw stuff like sockets, caps, resistors its easier to buy surplus. Check ebay or locally, you can get then for pennies. But there was one place that had nice socket samples, if you email me I can go find the site. (thomas997 at hotmail.com).

Local surplus or Ebay. And the last resort is the local electronics shop, I dont like to pay full price for basic parts...