I am a complete noob in electronics, i have not dabbled in it since school GCSE. I have a computer tower unit with a power button on the front.

What i want to do is this: when the power button on the front is pressed i want to have a DC motor connected to an arm Raise up and stop.

Not so hard that but the trick i cant get my head arround is this.

1 I dont want the circuit to power down if the button is re-pressed while the computer is on instead i want the circuit to run in reverse when the power is shutdown on the computer.

I thought perhaps the trick would be to find a line probably on the power button to motherboard where i could attach a circuit that would A if there is power go forwards (power arm circuit one way) and if there is no power there ie pc is turned off then it would Reverse circuit and shutdown.
I am also guessing here i would maybe need to use power from a spare molex cable so i think this would be 12volts.

Thanks in advance, Dave.

 

This might fit your requirements: 'listing some possible parts from All Electronics www.allelectronics.com Gear motor 6-12 V dc. 6 RPM ,Cat # DCM -24 S ; switch [ 2 ea ] SPDT, Cat # SMS-195 ; Relay to match PC,assuming 12V, Cat # 4PRLY-12, [ socket Cat # PRL-S ]. 4 pole relays easier to find than 3.

 

Thank you for the reply. I have replied also to your PM Thanks again.

 

So that you can follow current path, I have re drawn figure; PG 1 shows PC off relay [RY] deenergised , contacts as shown. RY has 3 poles A, B. & C, with power off armatures are up[ moving contacts].D & E are NC push button switches. + to M+ rotates motorclockwise. - to M+ ,rotation counter clockwise,arm going down. Starting at A9 TO BE CONTINUED

 

Starting at ground A9 current flows A9- A7-M+ M- -B4-B6-D2- D1 -C3 - C1 - PS+ . Motor continues CCW 'till arm trips D ,as shown PG 2. Tripping D motor stopps. Gnd.-A9-A7-M+ - M- -B4 - B6 - D2 STOP. Action is similar when arm is up Sw. E opens stopping M. PG 2, PC is turned on , relay closes , pretend armatures go down, A9 - A8 - M- -M+ - B5 - B6 - C2 - C3 - E1 - PS+.; motor turns CW untill arm trips E and shuts off. PG3; PC still on M is stopped. Following around open E stopps current flow. If you have more questions we now at least have lettering & numbers to referr to. The relay coil should match PC output. 4PDT ry might be easier to find than 3P. Have fun. Batteries OK as only drain is when motor is moving.

 

I'll try again

 

Thanks i kinda understand how it works now I will have to wait till i can scrounge some parts together and try wireing it up and see how she works from the diagrams Thanks for your time friend.

 

Ok i got my self confused again lol.first what is that symbol next to the Negative point on symbol PS ?? im presuming the PS is my power supply(Molex cable), and the symbol is the pc switch?
Ok i think im an idiot sorry mate. in re-typing this reply 5 times i think i understand how this circuit works. That symbol i thought was a switch IS a switch and is the power button? It now uses power from my molex cable? this circuit will activate rotating the arm to on position. In on Position PG3 The relay is on Which then sends signal to pc to turn on ????? is that right? If so how does relay know to shut off? as on depress of power button the state of the relay will be back to its start also.
i think i got confused out of my depth here. I look at circuit and it works in my head but i think it is not doing what i want it to do because i have not explaind my self properly. so i will try again or you can tell me to shut up fool and try again to explain to me
The power button on pc Has 2 wires on it. Im guessing while computer plugged in there is always current going from Motherboard to one side of this button awaiting for the initial press/release to complete the circuit and send signal to turn on Fig1
Once on the power button is in the same state ( i think) current wise as off with exception that pressing it again does not turn it on again obviously.(holding in for 5 to 10 seconds Insta turns pc off.)
This robot arm circuit would run on its own power from this molex cable which i have now confirmed is 12v,5amp,60watt rated.
On power down the circuit would not be affected if connected to power button which is in turn connected to the motherboard because the 2 connections to power button dont change in right way on shutdown they dont change at all as far as i know relay would not work in right way???
So this circuit in order to use the relay to determine the off state i guess need to connect to something else that has a true On if pc is on state and off when pc is off state like a Fan or the POWERED led light. so in essence the fan state could be the on/off switch for this circuit?
Thinking about it if using the Led status to determine if on or off would be easier?
If led is on then Activate Arm to rotate to on position and stop.Fig2a
If led is off then activate arm to rotate to off position and stop.Fig2b
Am i being stupid or am i making sense mate? I have tried to draw it best i can feel free to send me a msn message sometime if ya fancy chatting as i am keen to learn. thanks for your help

Not sure why my thumbnail doesnt bring up the page with main size picture but i posted link to it directly too.


Dave
MSN messenger damnnationx@hotmail.com

 

The strange symbol looks like an AND gate; and you plug it into an AC receptical and you have a powered up power supply [PS] delivering a voltage compatablle with your motor. This may be the same thing as your Molex cable [ needs to continously on ]. From PC , need a a voltage which is on when PC is on; off when PC is off, preffer 12V @ 50mA. Fan ? Your last paragraph is right on. Have to go bowling now.