Hardwiring multiple switches to common inputs

Hi all

Just a general question here, please help me try understand whats best to do in a situation like this:

I am using a 4511 IC to control digits 1-6. My inputs are six individual sing pole switches. Obviously the 4511 IC has 4 inputs, truth table can be found here: **broken link removed**

Here is a diagram of how I wanted to wire the circuit up...

**broken link removed**

Problem I can see here is that the inputs are all bridged, so when one switch is closed it will set inputs A,B,C to '1'.... which is not what I want obviously. How do I isolate each switches inputs? Diodes? Resistors?

Help please.

Thanks

Diodes are usually used for this, you will also need to add a pulldown resistor directly to each input pin including the D input.

like this?

**broken link removed**

Oh ya, and what do i connect terminal 'D' to if not in use.... just to ground? Or to V+??? (with the resistor of course)

hi ryan,
Pin 'D' on the 4511, will go to 0V gnd.
Dont forget the /EL, /BI and /LT pins, do you need help on how to connect these?

/EL to 0V.
/BT and /LT are +V

EDIT: The contacts on the 6 switches, which are shown on your drawing, as not connected, will have to go directly to the +V rail.
The +Vrail is the supply to the 4511.

Are the diodes in the correct place?
Its cool, I have a nice diagram for the 4511 which shows all the connections, and I've already wired up the 4511 to the diagram I have, and it works perfectly, I just need help integrating these 6 seperate switches to that circuit... Thanks!

hi,

> Are the diodes in the correct place?

The diodes look OK. Dont forget the pulldown resistors.

If you draw a truth table it will show the logic.

ericgibbs said:

The diodes look OK. Dont forget the pulldown resistors.

Click to expand...

The attachment will show the usual arrangement for switch and resistor. The diode is optional.

hi allvol,
On his project he is using the diodes as a 'gate' function, so the resistor will have to on the other side of the diode.

He his encoding 6 push buttons into a 4511

Regards