Solderless protoboard electrical limits

[Dave Boland]

I have tried to contact 3M and one other company that make
the white plastic solderless breadboards for electrical
information, but they have nothing. Has anyone in this
group seen any data that characterizes them for noise and
frequency response?

The circuits I want to work with have a lot of variants, are
all below 2 MHz, but noise may be an issue. This is just to
sort out some ideas, not to do critical testing, so there is
some flexibility here.

Another alternative would be prototype cards that components
can be soldered to. This will require more time to
breadboard, and may be more noisy because they are typically
2-Signal plain, 0-Power plain construction. I hate to take
the time do do my own card design/build until I have sorted
the circuits and all of their variants out a little.

Any ideas?

Thanks,
Dave

 

[[email protected]]

The circuits I want to work with have a lot of variants, are
all below 2 MHz, but noise may be an issue. This is just to
sort out some ideas, not to do critical testing, so there is
some flexibility here.

2MHz is certainly within their 'digital' bandwidth. Capitance would be
a factor at higher frequencies.

For analog noise I don't know. You could put a ground plane under the
whole thing, but it would be quite a bit further away than the other
side of a PCB. Probably not good in the presence of strong RF from
nearby sources either - you could perhaps get rectification in oxidized
spring-clip to lead connections, and can probably couple in more noise
in the interconnects than you would get with point to point coax or PCB
stripline.

Traditional prototype construction for small signal RF circuits is
"dead bug" - put ICs, transistors, etc upside down over unetched
copper, wire most connections in the air, with anything that goes to
ground soldered to the board. You can also add extra high value
resistors as standoffs. Not so much fun today with TSSOP IC's, but you
can build little stonehenge replicas with chip resistors and caps...

 

[Tim Wescott]

Dave Boland wrote:




2MHz is certainly within their 'digital' bandwidth. Capitance would be
a factor at higher frequencies.

For analog noise I don't know. You could put a ground plane under the
whole thing, but it would be quite a bit further away than the other
side of a PCB.

Quite a bit closer, actually -- the bottoms of those spring clips are
just an adhesive label away from the bottom of the board. I have one
that I use for prototyping oscillators up to 10MHz or so that's on
standoffs. Note that at 10MHz the only piece of information that I
consider valid is that it'll actually oscillate once I get it onto a
dead-bug style board.

Probably not good in the presence of strong RF from
nearby sources either - you could perhaps get rectification in oxidized
spring-clip to lead connections, and can probably couple in more noise
in the interconnects than you would get with point to point coax or PCB
stripline.

When I use those I am careful to keep the wires tight against the board
surface -- no big loop! It makes a significant difference.

Traditional prototype construction for small signal RF circuits is
"dead bug" - put ICs, transistors, etc upside down over unetched
copper, wire most connections in the air, with anything that goes to
ground soldered to the board. You can also add extra high value
resistors as standoffs. Not so much fun today with TSSOP IC's, but you
can build little stonehenge replicas with chip resistors and caps...

Yup. I just prototype with through-hole components. If I got serious
with RF stuff I'd prototype with quick-turn boards. Usually even a bad
guess at a circuit is a pretty good starting point for a cuts & jumps fix.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

 

[Tim Wescott]

I have tried to contact 3M and one other company that make the white
plastic solderless breadboards for electrical information, but they have
nothing. Has anyone in this group seen any data that characterizes them
for noise and frequency response?

The circuits I want to work with have a lot of variants, are all below 2
MHz, but noise may be an issue. This is just to sort out some ideas,
not to do critical testing, so there is some flexibility here.

Another alternative would be prototype cards that components can be
soldered to. This will require more time to breadboard, and may be more
noisy because they are typically 2-Signal plain, 0-Power plain
construction. I hate to take the time do do my own card design/build
until I have sorted the circuits and all of their variants out a little.

Any ideas?

Thanks,
Dave

With careful layout you can do narrowband (i.e. radio) stuff up to
2-5MHz -- I prototype oscillators up to 10MHz, but I'm mostly looking
for gain margins and "will it oscillate with these components" before I
move the thing to dead-bug or soldered breadboard. I don't think I'd
trust it for a _broadband_ signal beyond 500kHz or so, and even there
I'd take my results with a grain of salt.

I think that you could push these up pretty high with careful layout,
and consideration for what you want to learn. If, for instance, you
don't know if a circuit is going to work at all but you're confident
that you can deal with EMI considerations if it does you can breadboard
it, test it for the stuff that a breadboard won't screw up, then either
scrap it or put it on a PC.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

 

[Tim Shoppa]

I have tried to contact 3M and one other company that make
the white plastic solderless breadboards for electrical
information, but they have nothing. Has anyone in this
group seen any data that characterizes them for noise and
frequency response?

The circuits I want to work with have a lot of variants, are
all below 2 MHz, but noise may be an issue. This is just to
sort out some ideas, not to do critical testing, so there is
some flexibility here.

Well, fundamentally the limited frequency response is a property of the
capacitance between protoboard conductors. 10-20-30pF is the ballpark
depending on geometry.

And "noise", that is not a product that they put into the breadboard.
Any noise you see on a protoboard can be attributed to lack of a ground
plane, long Vcc and ground lines, big loops in the wiring that pick up
external noise, etc. Those are all properties of the construction
details (although of course you've chosen to do it on a protoboard so
you can't get good short lines.)

Long wires etc. also limit frequency response by introducing
inductance.

Another alternative would be prototype cards that components
can be soldered to. This will require more time to
breadboard, and may be more noisy because they are typically
2-Signal plain, 0-Power plain construction. I hate to take
the time do do my own card design/build until I have sorted
the circuits and all of their variants out a little.

Any ideas?

"Dead bug" construction is surprisingly quick and effective.

Tim.

 

[Tim Shoppa]

With careful layout you can do narrowband (i.e. radio) stuff up to
2-5MHz -- I prototype oscillators up to 10MHz, but I'm mostly looking
for gain margins and "will it oscillate with these components" before I
move the thing to dead-bug or soldered breadboard. I don't think I'd
trust it for a _broadband_ signal beyond 500kHz or so, and even there
I'd take my results with a grain of salt.

In the digital domain protoboards are useful up to the 10-20MHz region
without a lot of effort. Although it takes some thought. At the same
time it's trivial to come up with examples that will not work at 1MHz
if you put awful long wires on grounds and Vcc's etc.

If you scope out the ground pin on a TTL IC at just 20MHz on a
protoboard you can see horrendous bounce! CMOS or HC isn't so bad (but
it's still plainly visible on a scope). "Flyover" jumpers turn a nice
square 8MHz clock into a ugly wiggly blob after just a few inches, and
attempting to clock more than a few chips at once will probably be a
disaster. But overall you'd have similar problems on a similarly
laid-out PC board (strangely enough you will have the same problem on
some of those pre-etched protoboards!)

Tim.

 

[Tim Williams]

I don't think I'd
trust it for a _broadband_ signal beyond 500kHz or so, and even there
I'd take my results with a grain of salt.

*Shrug* I'm listening to a breadboarded discrete audio amplifier right now
that does sinewaves out to 300kHz. Probably a lot more if I upped the bias
and switched in faster output transistors.

Layout helps a lot, though. First time I assembled the circuit, the driver
transistor(s) oscillated around 100MHz. You can't even see that on a slow
scope!

Tim

 

[[email protected]]

[email protected] wrote:

Quite a bit closer, actually -- the bottoms of those spring clips are
just an adhesive label away from the bottom of the board.

The contact in the breadboard, yes. But the components would be a lot
further away. I guess maybe that's more of a comparison to a ground
(+power) plane as a low inductance supply issue than a ground plane as
an RF shield.

 

[Joseph2k]

I have tried to contact 3M and one other company that make
the white plastic solderless breadboards for electrical
information, but they have nothing. Has anyone in this
group seen any data that characterizes them for noise and
frequency response?

The circuits I want to work with have a lot of variants, are
all below 2 MHz, but noise may be an issue. This is just to
sort out some ideas, not to do critical testing, so there is
some flexibility here.

Another alternative would be prototype cards that components
can be soldered to. This will require more time to
breadboard, and may be more noisy because they are typically
2-Signal plain, 0-Power plain construction. I hate to take
the time do do my own card design/build until I have sorted
the circuits and all of their variants out a little.

Any ideas?

Thanks,
Dave

Personally i have found that digital gets flaky around 10MHz and analog can
get flaky at 200kHz and is always flaky by 2MHz.