transistor help please :)

[SebbeK]

I'm having some troubles here...
I have a casio pt-10 which has a sequenser with a button that steps the sequens one note at a time. The idea is to step the sequense with a 555 timer.
The button connects two points at the IC but none of them are ground or 6v+ (the main current)...
So i've tried to make a transistor connect the points... but i can't get it to work properly.

This is the ways i've tried:

the transistor is npn

+ ------------
             |
  resistor []
             |------------------trigger 1
             |   collector
555------(-{ )
             |   emitter
             |
         trigger 2



           trigger1
             |
             |   collector
555------(-{ )
             |   emitter
             |
         trigger 2

Any ideas? I don't want to use a switch ic for this... Should work with a transistor.
For some strange reason it starts the demo song when i do this.... :S
actually... sometimes it works. But eventually it starts the demo anyways. This is odd. It works great to step it using just a wire, but with the transistor circuit i can't get it to work properly

[Matt the Modulator]

you could use a cd4066 or cd4016 bilateral switches - both of these chips have 4 switches a positive trigger from the a 555 time connects two points just like a switch
a data sheet for the cd4066 can be found here www.fairchildsemi.com/ds/CD%2FCD4066BC.pdf
you could also try a reed switch ?? i don't know much about them but velleman sell a kit which uses a 555 timer and a reed switch ?? check the velleman web page they have all the schematic there as well

[Dj Task Manager]

Im having troubs with some 4066 chips ive got, anyone know of a simple example circuit diagram?  I thought I could just power it then zap 5vs from the Vdd to trigger one of the switches but this doesnt seem to work.  Infact the LED im using to test if the switch closes is always lit up even when theres nothing going to its corresponding trigger.  WIERD!

[Dj Task Manager]

Im having troubs with some 4066 chips ive got, anyone know of a simple example circuit diagram?  I thought I could just power it then zap 5vs from the Vdd to trigger one of the switches but this doesnt seem to work.  Infact the LED im using to test if the switch closes is always lit up even when theres nothing going to its corresponding trigger.  WIERD!

I think it maybe something to do with 'pull resistors' but I dont really have a clue what that means :s

[Circuitbenders]

It might be useful if you post a diagram of what you've actually got.

Have you got all the unused inputs tied to ground, and do you have a current limiting resistor on your LED? What kind of voltage ar you trying to switch for the LED power.

If you wire up the IC power (+5v) and ground, and wire pin 14 (VDD) to pin 11, then 5v applied to pin 12 should give you 5v at pin 10. The 5v at pin 12 should close the switch between pin 11 (5v) and pin 10.
You can wire an LED to ground via a current limiting resistor from pin 10, and it should light whenever you apply 5v to pin 12.

[Dj Task Manager]

Appologies, Youre right I should have been more explicit! 
Yeah I was wiring it as you described, and with the other inputs going to ground, but it is behaving as stated previously.  What resistor would you use for the led?
I'll take it to my local hackspace tonight I recon.

Cheerz!

[Circuitbenders]

actually, thinking about it again, if you were trying to light an LED you'd do a lot better to send the output of the 4066 on pin 10 to a transistor and use that to switch the LED on an off.

Kind of like this:
http://zedomax.com/blog/2007/02/12/transistor-and-led-howto/

With a 5v supply the 4066 won't be able to supply enough current to light the LED directly.

Can't you test this by connecting the continuity tester of a a multimeter to pins 10 and 11 and connecting 5v to pin 12? It should beep when you connect the 5v to indicate a closed switch.

[Dj Task Manager]

Good thinking I'll abandon the LED and use a multimeter.  Its being used in a sequencer to simulate key/button presses on keyboards, hooking up the 4066 switch terminals to 3.5mm jacks for connectivity.

Thanks for your help!