ADC path switching

[BeanieBots]

Another thought though, could the PICAXE power the MC14551B. Connecting the output of one of the pins directly to VDD (pin 16) of the MC14551B? Or would it need a driver?

This control would allow me to turn the joysticks on and off as well.

No, you won't be able to do that.
I'm quite sure the PICAXE could power the MC14551B (a quick read of the datasheet would confirm) but if you don't 'switch off' the joysticks at the same time you risk destroying the MC14551B.
A restriction of any semiconductor analogue switch (again stated in the datasheet) is that any input voltage to the switch must fall between its power rail voltages. If it's not powered, that's not much voltage!

 

[westaust55]

A relay would be too big, so I agree it would be best to have an 08M control a multiplexer. However, I reckon I'll use the MC14551B because I need to switch 4 analogue paths with as smaller footprint as possible.

I still haven't got much space, so I'll need to knock up some designs to see if it all fits.

I have not read all the early posts but is the MC14551B the right chip for your applciation.
The MC14551B is a quad 2-channel (2 to 1) analog switch with a single control pin that changes all 4 switches at the same time. In a 16 pin package
The 4066 is a quad 1 channel (on/off) analog switch chip with a separate control pin for each of the 4 chips. In a 14 pin package.
For a multiplexer (the term you use in post 37) I would think the 4066 would be a better choice


EDIT:
But for an analogue A-B switch as you mention in post 39 suggests, then yes the MC14551B is a better choice

Might be good to make it clear exactly what the aim/goal is.

 

[westaust55]

Looking at datasheets today for a chip to act as an A-B switch for both digital and analogue signals. Was thinking about the MC14551B that had been identified in this thread but found it to not be readily available here (WA) so started looking at other options of a solid state nature.

While searching, came across the CD4051/52/53 series.
EDIT: also available as 74HC series parts 74HC4051/52/53

Ron (the switch On-state resistance) values for a 5Vdc supply are similar to the 4066 and MC14551B at 270 Ohms typical and 1050 Ohms max.

4051 is 8 x 1 channel switches
4052 is 2 x 4 channel switches
4053 is 3 x 2 channel switches

4053 does the 8 possible permutations of switching between the three switches and their A-B options.


That CD4053 is looking very versatile as an alternative to the 4 x 2-channel MC14551 since I need only 3 A-B switches. Just tie all selector pins together for A-B switch or break out selector pins as required for up to 8 options