question on viewing VSS and Vgnd pins on 4017DB 5-stage John

Guest
Greetings,

I'm trying to connect a 555 timer circuit to a 4017DB 5-stage Johnson counter in Multisim 8 how does one get the Vss and Vgnd pins to show up on the 4017DB 5-stage Johnson counter so I can connect them to the 555 timer?
Example of the circuit
http://www.allaboutcircuits.com/vol_6/chpt_7/6.html
The pins are different why?

is thier a group dedicated to multisim or electronic work bench I should/could post to?


Thanks
 
<sal@spp.net> wrote in message
news:yP4ee.267$Wq.178@bignews4.bellsouth.net...
Greetings,

I'm trying to connect a 555 timer circuit to a 4017DB 5-stage Johnson
counter in Multisim 8 how does one get the Vss and Vgnd pins to show up on
Click to expand...
the 4017DB 5-stage Johnson counter so I can connect them to the 555 timer?
Example of the circuit
http://www.allaboutcircuits.com/vol_6/chpt_7/6.html
The pins are different why?

is thier a group dedicated to multisim or electronic work bench I
should/could post to?


Thanks
Click to expand...
Vss is ground, it's just the designation used for with MOS transistors. Vdd
is the power supply
as Vcc is for TTL devices. It doesn't matter that you show your 555 ground
connected to Vss
so long as Multisim knows it's ground.

Using real components, one wouldn't jump the ground of one chip to the
ground of the other.
Rather you would connect your power source and ground to the plug board
power rails and
simply jump the chip power pins to the appropriate rail.

There are situations where grounds are isolated but this is not one.
 
Lord Garth wrote:

Using real components, one wouldn't jump the ground of one chip to the
ground of the other.
Rather you would connect your power source and ground to the plug board
power rails and
simply jump the chip power pins to the appropriate rail.
Click to expand...
Why is that? Jumping the ICs' ground-pins or making a separate coupling
from each GND-pin to the GND-rail they will still be electrically common,
won't they?

--
Rikard Bosnjakovic http://bos.hack.org/cv/

Anyone sending unwanted advertising e-mail to my address will be
charged $250 for network traffic and computing time. By extracting
address from this message or its header, you agree to these terms.
 
On Thu, 05 May 2005 03:56:57 +0000, Lord Garth wrote:
"Rikard Bosnjakovic" <bos@REMOVETHIShack.org> wrote in message
Lord Garth wrote:

Using real components, one wouldn't jump the ground of one chip to the
ground of the other.
Rather you would connect your power source and ground to the plug board
power rails and
simply jump the chip power pins to the appropriate rail.

Why is that? Jumping the ICs' ground-pins or making a separate coupling
from each GND-pin to the GND-rail they will still be electrically common,
won't they?

It's convenient to connect the power to a near-by bus. Wide power traces
are better than narrow traces impedance wise and the wide trace also
provides
an easy place to solder on a decoupling capacitor very close to the IC.
Further, many schematics presume you know the chip needs power so they
may not be shown.
Click to expand...
The power and ground are clearly shown on the pictorial, albeit they've
omitted any bypass caps. The OP was asking how to connect them in his
simulator program. For that, I'd say check the program's docs.

"sal" had written:
"I'm trying to connect a 555 timer circuit to a 4017DB 5-stage Johnson
counter in Multisim 8 how does one get the Vss and Vgnd pins to show
up on the 4017DB 5-stage Johnson counter so I can connect them to the
555 timer?
Example of the circuit
http://www.allaboutcircuits.com/vol_6/chpt_7/6.html
The pins are different why?"

I'm guessing that sal is saying that the 555 connection looks different
from the ones in the data books. It's not a problem - it just makes very
narrow pulses - the discharge resistor is zero plus parasitics.

Cheers!
Rich
 
"Rich Grise" <richgrise@example.net> wrote in message
news:pan.2005.05.05.16.36.40.124936@example.net...
On Thu, 05 May 2005 03:56:57 +0000, Lord Garth wrote:
"Rikard Bosnjakovic" <bos@REMOVETHIShack.org> wrote in message
Lord Garth wrote:

Using real components, one wouldn't jump the ground of one chip to
the
ground of the other.
Rather you would connect your power source and ground to the plug
board
power rails and
simply jump the chip power pins to the appropriate rail.

Why is that? Jumping the ICs' ground-pins or making a separate
coupling
from each GND-pin to the GND-rail they will still be electrically
common,
won't they?

It's convenient to connect the power to a near-by bus. Wide power
traces
are better than narrow traces impedance wise and the wide trace also
provides
an easy place to solder on a decoupling capacitor very close to the IC.
Further, many schematics presume you know the chip needs power so they
may not be shown.

The power and ground are clearly shown on the pictorial, albeit they've
omitted any bypass caps. The OP was asking how to connect them in his
simulator program. For that, I'd say check the program's docs.

"sal" had written:
"I'm trying to connect a 555 timer circuit to a 4017DB 5-stage Johnson
counter in Multisim 8 how does one get the Vss and Vgnd pins to show
up on the 4017DB 5-stage Johnson counter so I can connect them to the
555 timer?
Example of the circuit
http://www.allaboutcircuits.com/vol_6/chpt_7/6.html
The pins are different why?"

I'm guessing that sal is saying that the 555 connection looks different
from the ones in the data books. It's not a problem - it just makes very
narrow pulses - the discharge resistor is zero plus parasitics.

Cheers!
Rich
Click to expand...

I presuming that Multisim doesn't show the power and ground inputs
since that's a given. I could be wrong, I don't own a copy so I'm WAGing!
 
"Rikard Bosnjakovic" <bos@REMOVETHIShack.org> wrote in message
news:Qncee.23318$d5.170001@newsb.telia.net...
Lord Garth wrote:

Using real components, one wouldn't jump the ground of one chip to the
ground of the other.
Rather you would connect your power source and ground to the plug board
power rails and
simply jump the chip power pins to the appropriate rail.

Why is that? Jumping the ICs' ground-pins or making a separate coupling
from each GND-pin to the GND-rail they will still be electrically common,
won't they?

--
Rikard Bosnjakovic http://bos.hack.org/cv/
Click to expand...
It's convenient to connect the power to a near-by bus. Wide power traces
are better than narrow traces impedance wise and the wide trace also
provides
an easy place to solder on a decoupling capacitor very close to the IC.
Further, many schematics presume you know the chip needs power so they
may not be shown.
 
Looking at SCHEMATIC DIAGRAM, the 555 does NOT appear to be wired for

"Use of a 555 timer circuit to produce "clock" pulses (astable
multivibrator)"

Take a look at:
http://www.uoguelph.ca/~antoon/gadgets/555/555.html
for some information on the 555.

Dave
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top