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Hardwiring multiple switches to common inputs

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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.
 
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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.

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

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  • onswitch.JPG
    onswitch.JPG
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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
 
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