I want to design a circuit that will let a single button have two functions: 1. When the pc is not running it will function as the power on button. Once the pc is on the switch cannot turn the computer off that must be done through windows. This is where it gets tricky... 2. Once the computer is running the switch would then become the drive eject button. If this is even possible I would really appreciate if someone could help me design the circuit.
This could be done with a relay or a flip flop. I'll explain using the relay (cuas i think its easyer to visualise). Code: | | /````````+5vdc from the standard molex conector | \ coil | / | | \________ gnd from the standard molex conector | eject button circuit | power jumper when the computer is running, (the cd drive would have power) the relay will caus the contact to move to the cd drive circuit. when it has no power (ie the comp is off) it will sit in the power switch circuit.
If you don't like relays you could use the power-LEDs cicuit to turn some transistors on or off. Or just use the 12v/5v line. It wouldn't really matter if the pulse from the button went to both the power and eject buttons at startup... [edit] hmm, will it work? ill have to think some more , or let someone else do it for me
Just use a relay as mentioned above, make sure it has the right number of polls on it for your needs. Read up on switch types if you're not sure.
Im no electronics buff so I have no idea what youre talking about, If you could tell me what kind of relay I should be looking for and possibly a better diagram would help.
I've been thinking about this for a lil while. In this case it's going to be a Power/Reset button, all in one. My idea is to use a shift register.
r3men4nt lets try to understand the relay one. All a relay is, is a coil (electro-magnet), 2 sets of conatacts, and a switch that moves between them. The switch (or paddle) is held by a spring to one side, allowing a completed circuit on that contact pair. When a power is applied to the coil, the magnet force pulls the paddle towards the other set of contacts, making a complete circuit on the pair near the coil, breaking the circuit on the pair away from the coil. Hope that makes sense, if not try google. The relay solution isn't the best because it will take a lot of power (to keep the magnetic feild held). But it might be the simplest if you use a latching relay!
I know he is probably confused enough as it is, but could you use a j-fet to disable the connection to the power header when the main power comes online?
A shift register is an IC, CMOS 4015. Right now I'm busy and didn't have time to keep going with my idea.
