i am going to experiment with some CMOS logic gate chips like CD4071BE, 4011, 4081, etc.
would like some feedback on what would be best practice for supplying the power.
i figure there would be two basic options like the diagram below;
since i will be having all chips on simultaneously, the circuit in option 1 & 2 are the same, right ?
i will echo the same for the GND, ie. either daisy-chain or individual branches.
i have not included decoupling capacitors in the picture - i plan to put a 0.1 uF cap across each IC and an extra 10uF (?) on the power rail itself. (power supply will be 5V or possibly 9.6 V)
would there be any other considerations why one would choose one over the other ?
No, option 2 is better. In option 2 all chips get the supply voltage. In option 1 the left chip gets supply voltage, the next chip gets supply voltage minus the voltage drop of the wire, the next supply voltage minus 2 voltage drops and so on. For short wires it won't matter much, but when wires get longer it will.
It is the same with grounds. All grounds should go to one place (star grounding).
groundFungus:
No, option 2 is better.
...left chip gets supply voltage, the next chip gets supply voltage minus the voltage drop of the wire, the next supply voltage minus 2 voltage drops and so on. For short wires it won't matter much, but when wires get longer it will.
ahh, yes i see now - the chip furthest to the right gets the longer/-st wire, making for inconsistency.
groundFungus:
It is the same with grounds. All grounds should go to one place (star grounding).
i see - and ideally, the same point- not just "same rail" on a breadboard which will have some capacitance issues, too, right ?
(now i see what a "ground plane on a PCB is for !)
Make sure you have a reasonably well connected grid of ground wires over the breadboard, so that there
are return paths for signals that don't have to go round the houses. If the ground connections are
like a square grid on a 1 to 1.5 inch pitch, you'll probably be able to work with logic to 20MHz or so
without too many problems, and less demanding signals ought to be reliable. Its an approximation to
a ground-plane.
Options 1 and 2 are pretty similar really, use either/both, whatever is neater?
MarkT:
Make sure you have a reasonably well connected grid of ground wires over the breadboard, so that there
are return paths for signals that don't have to go round the houses. If the ground connections are
like a square grid on a 1 to 1.5 inch pitch, you'll probably be able to work with logic to 20MHz or so
without too many problems, and less demanding signals ought to be reliable.
ooh, that fast even, huh ?
good to know, thanks !
MarkT:
Its an approximation to a ground-plane.
ahh - i'm learning fundamentals every day !
MarkT:
Options 1 and 2 are pretty similar really, use either/both, whatever is neater?
yeah - that was my thinking - Option 1 does look neater (IMO)
but it was good to be made aware (of what should've been obvious actually) that they are different because of the wire lengths. (insignificant though they may be at this small scale)
ted:
I you are using what is on your picture power supply is not critical, however if additionally you have low level analog signal that can be issue.
ah yes, i get it - so a 9V power supply would be better than the 5V, if only to get a better differential range for 'low' and 'high'.
