2
\$\begingroup\$

I have checked stachexhange for my answer, but no luck. I hope I can be helped here. I am building ben eater's 8-bit, and have a general question about wiring: Is it better (less impedance/resistance) to use ONE long jumper with bends, or should I use NUMEROUS as-short-as-possible jumpers to connect the end points?

example 1, in wiring ground and Vcc from one side of an 830 point BB, would it be better just to directly connect ground on one side, to the ground on the other side (same for Vcc)? OR would it be better to connect a small jumper from ground to column 1A, then another small jumper from column 1E to column 1F, then finally from 1J to the ground on the other side (and an analogous wiring scheme for Vcc). Ie one long bent jumper, versus multiple short straight jumpers?

Example two: (direct/bend) In connecting pins on chips from one BB to another is it better to use one wire between those chips, and bend the wire to accomplish this? OR (incremental) Would it be better to connect the pins on chips from different BBs using the incremental method as described above? Again, one long bent jumper, versus multiple short straight jumpers?

Any info would be helpful. Thanks to all of you in advance. Best...

\$\endgroup\$
  • 2
    \$\begingroup\$ I'm not exactly an expert on breadboards, but I think if you're getting to a point where that matters, you should stop using a breadboard and use at least stripboard, preferably a custom PCB. \$\endgroup\$ – Hearth Mar 3 '19 at 4:21
  • \$\begingroup\$ thanks for your response. yes, that is my next step. wanted to do it on breadboard first since I am a newbie, and need to make a lot of corrections............ \$\endgroup\$ – joescar Mar 3 '19 at 19:19
3
\$\begingroup\$

It's not going to make a lot of difference -- it's the path the signal takes, not whether it's confined to a wire or using the conductors on the breadboard.

For things like grounds, having multiple ground ties between the ground busses is a good idea. Good chip bypassing is essential (not just "even on a breadboard" but especially on a breadboard).

\$\endgroup\$
  • 3
    \$\begingroup\$ And finally, in a comment because this is an opinion, trying to build big, high-speed circuits on breadboards is kind of like powering your dragster with a Ford flathead V-8. It's a fun way to try to overcome the limitations of a specific technology, but it may not be an efficient use of your personal resources of time and money. \$\endgroup\$ – TimWescott Mar 3 '19 at 4:43
  • \$\begingroup\$ thank you for responding. thats good news. i am trying to keep the jumpers under control and one way to accomplish that is to use multiple short wires. i appreciate your analogy....i think i have to continue on breadboard at least until I finish this project (my first), then I will move onto other more permanent solutions.............. \$\endgroup\$ – joescar Mar 3 '19 at 19:23
2
\$\begingroup\$

The two examples you provide, one for distributing power and the other for distributing a signal, deserve different answers. The reason is that every time you push a wire into the breadboard you add significant capacitance to that wire. The little metal fingers under the plastic act like capacitor plates to each other.

For power distribution, capacitance is good. It helps to provide large transient current when the clock changes and all of your logic gates wiggle. You should use many redundant wires to distribute ground and power. Make lots of connections between the various ground and power lines on the breadboards...the long runs of many holes connected together, at right angles to the signal connections.

Just to be clear, you need to add capacitors to your breadboard to provide power supply bypassing. A conservative approach is to use something like 0.1\$\mu\$F or 0.01\$\mu\$F directly at the supply and ground pins of every IC. My point here is that the added capacitance of the breadboard is not a detriment.

For signal wiring, capacitance is bad. It slows down your signal transitions and increases power consumption. Make those connections with a single wire, bending as necessary.

\$\endgroup\$
  • 1
    \$\begingroup\$ The capacitance you get from a breadboard while enough to be an impediment to high speed signals is orders of magnitude too small to be an asset for power. So doing it for that reason is erroneous thinking. And each joint introduces a failure point. It's probably worth using the power busses for neatness though. \$\endgroup\$ – Chris Stratton Mar 3 '19 at 14:37
  • \$\begingroup\$ @ChrisStratton Agreed, regarding the potential failures of a joint. Which is why I recommended many redundant wires. And I wasn't trying to suggest that the breadboard capacitance would replace proper power supply bypassing, I'll edit the answer to add that. \$\endgroup\$ – Elliot Alderson Mar 3 '19 at 15:44
  • \$\begingroup\$ to elliot alderson.....thanks for very clear and helpful response!!!! \$\endgroup\$ – joescar Mar 4 '19 at 4:44

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.