All opinions welcome !
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Posts: 46,084
Hey all !
This is all pretty new to me, but here goes.
I am looking for opinions/suggestions about the project that I am
working on (A Question and Answer display to be used for an annual
Fire Prevention Expo run by my firehouse.)
I have uploaded the schematic, pcb layout, and source code associated
to this address:
http://groups.yahoo.com/group/basicstamps/files/Quizboard/
I am especially interested in comments on my output section design.
I am a little concerned with the coupling of 2 dissimilar voltage
levels (+5V regulated and +12V unregulated)and their effect on the
circuit.
If you have a few moments to look over my design, I would appreciate
any advice that you could offer.
Thanks
C.C.
This is all pretty new to me, but here goes.
I am looking for opinions/suggestions about the project that I am
working on (A Question and Answer display to be used for an annual
Fire Prevention Expo run by my firehouse.)
I have uploaded the schematic, pcb layout, and source code associated
to this address:
http://groups.yahoo.com/group/basicstamps/files/Quizboard/
I am especially interested in comments on my output section design.
I am a little concerned with the coupling of 2 dissimilar voltage
levels (+5V regulated and +12V unregulated)and their effect on the
circuit.
If you have a few moments to look over my design, I would appreciate
any advice that you could offer.
Thanks
C.C.
Comments
diagramatically as the base, but is connected to the 12V thru a pot
and speaker.
The same is foru for all the transistors. but once you correct that
it seems you just need to verify base voltage needed to drive the
higher voltage.
as it is now, I would worry about putting the higher voltage into the
pins.
Dave
--- In basicstamps@yahoogroups.com, "captainconstructor"
<captainconstructor@y...> wrote:
> Hey all !
>
> This is all pretty new to me, but here goes.
> I am looking for opinions/suggestions about the project that I am
> working on (A Question and Answer display to be used for an annual
> Fire Prevention Expo run by my firehouse.)
>
> I have uploaded the schematic, pcb layout, and source code
associated
> to this address:
>
> http://groups.yahoo.com/group/basicstamps/files/Quizboard/
>
> I am especially interested in comments on my output section design.
> I am a little concerned with the coupling of 2 dissimilar voltage
> levels (+5V regulated and +12V unregulated)and their effect on the
> circuit.
>
> If you have a few moments to look over my design, I would appreciate
> any advice that you could offer.
>
> Thanks
> C.C.
First off, thank you for taking the time..
You were right, I had changed components earlier and moved the pins,
but never re-oriented the symbol. I have edited the posted schematic
to reflect the proper connections.
http://groups.yahoo.com/group/basicstamps/files/Quizboard/Expresssch.pdf
About the gate drive voltage... I currently have 247 Ohm resistors
acting as output current limiting devices. I am not sure how much
Drain - Gate leakage I need to worry about so I was considering
raising these values to increase protection. From what I
understand, the Logic level MOSFETs need only the presence of voltage
at the gate with a bare minimum of current. Do you have any experience
with these devices?
Thanks, again
C.C.
--- In basicstamps@yahoogroups.com, "Dave Mucha" <davemucha@j...>
wrote:
> check Q1 for which wire goes to the base. pin 2 shows
> diagramatically as the base, but is connected to the 12V thru a pot
> and speaker.
>
> The same is foru for all the transistors. but once you correct
that
> it seems you just need to verify base voltage needed to drive the
> higher voltage.
>
> as it is now, I would worry about putting the higher voltage into
the
> pins.
>
> Dave
>
>
>
>
> --- In basicstamps@yahoogroups.com, "captainconstructor"
> <captainconstructor@y...> wrote:
> > Hey all !
> >
> > This is all pretty new to me, but here goes.
> > I am looking for opinions/suggestions about the project that I
am
> > working on (A Question and Answer display to be used for an annual
> > Fire Prevention Expo run by my firehouse.)
> >
> > I have uploaded the schematic, pcb layout, and source code
> associated
> > to this address:
> >
> > http://groups.yahoo.com/group/basicstamps/files/Quizboard/
> >
> > I am especially interested in comments on my output section
design.
> > I am a little concerned with the coupling of 2 dissimilar voltage
> > levels (+5V regulated and +12V unregulated)and their effect on
the
> > circuit.
> >
> > If you have a few moments to look over my design, I would
appreciate
> > any advice that you could offer.
> >
> > Thanks
> > C.C.
<captainconstructor@y...> wrote:
> Dave,
> First off, thank you for taking the time..
> You were right, I had changed components earlier and moved the pins,
> but never re-oriented the symbol. I have edited the posted schematic
> to reflect the proper connections.
>
>
http://groups.yahoo.com/group/basicstamps/files/Quizboard/Expresssch.p
df
>
> About the gate drive voltage... I currently have 247 Ohm resistors
> acting as output current limiting devices. I am not sure how much
> Drain - Gate leakage I need to worry about so I was considering
> raising these values to increase protection. From what I
> understand, the Logic level MOSFETs need only the presence of
voltage
> at the gate with a bare minimum of current. Do you have any
experience
> with these devices?
> Thanks, again
> C.C.
The odd thing is that the origional link works, but the one above
does not.
http://groups.yahoo.com/group/basicstamps/files/Quizboard/
The NTE2980 MOSFET
http://www.nteinc.com/specs/2900to2999/pdf/nte2980.pdf
I would total all the outputs and then figure the max current the
Stamp will handle and divide that by the count of outputs to make
sure you do not try ot load up the power supply too much.
If you are really concenred, use a 2803 darlington for 8 channels of
output that will act as a isolator and will offer more than enough
power to the MOSFETs. But I think that is overkill.
Dave
extention and removed it from the link..sry bout that.
The NTE link did the trick! I had been working from package and
catalog specs. The Gate - source leakage is too low to be concerned
about (100nA at 10V input should be 50nA at 5V) I'm going to increase
the "buffer" resistors to 10K or so each.
I'll let ya know where the smoke comes from...:-)
Thanks
C.C.
--- In basicstamps@yahoogroups.com, "Dave Mucha" <davemucha@j...>
wrote:
> The odd thing is that the origional link works, but the one above
> does not.
>
> http://groups.yahoo.com/group/basicstamps/files/Quizboard/
>
> The NTE2980 MOSFET
> http://www.nteinc.com/specs/2900to2999/pdf/nte2980.pdf
>
> I would total all the outputs and then figure the max current the
> Stamp will handle and divide that by the count of outputs to make
> sure you do not try ot load up the power supply too much.
>
> If you are really concenred, use a 2803 darlington for 8 channels
of
> output that will act as a isolator and will offer more than enough
> power to the MOSFETs. But I think that is overkill.
>
> Dave
for schematics, boards, parts, to control devices, relays, etc. with the
stamps.
jim
Original Message
From: Dave Mucha [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=a6vKs24h2nWBHg_4JZaCAMVfkr94LC1FN_8rS00XAWIjeqQ_135vSpnzezkuloqP9BFLeNvi8jTT-eCb]davemucha@j...[/url
Sent: Saturday, September 06, 2003 10:34 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: All opinions welcome !
check Q1 for which wire goes to the base. pin 2 shows
diagramatically as the base, but is connected to the 12V thru a pot
and speaker.
The same is foru for all the transistors. but once you correct that
it seems you just need to verify base voltage needed to drive the
higher voltage.
as it is now, I would worry about putting the higher voltage into the
pins.
Dave
--- In basicstamps@yahoogroups.com, "captainconstructor"
<captainconstructor@y...> wrote:
> Hey all !
>
> This is all pretty new to me, but here goes.
> I am looking for opinions/suggestions about the project that I am
> working on (A Question and Answer display to be used for an annual
> Fire Prevention Expo run by my firehouse.)
>
> I have uploaded the schematic, pcb layout, and source code
associated
> to this address:
>
> http://groups.yahoo.com/group/basicstamps/files/Quizboard/
>
> I am especially interested in comments on my output section design.
> I am a little concerned with the coupling of 2 dissimilar voltage
> levels (+5V regulated and +12V unregulated)and their effect on the
> circuit.
>
> If you have a few moments to look over my design, I would appreciate
> any advice that you could offer.
>
> Thanks
> C.C.
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--- In basicstamps@yahoogroups.com, "Jim Forkin" <jjf@p...> wrote:
> check out http://www.geocities.com/jimforkin2003/
> for schematics, boards, parts, to control devices, relays, etc. with the
> stamps.
> jim
>
>
Original Message
> From: Dave Mucha [noparse][[/noparse]mailto:davemucha@j...]
> Sent: Saturday, September 06, 2003 10:34 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: All opinions welcome !
>
>
> check Q1 for which wire goes to the base. pin 2 shows
> diagramatically as the base, but is connected to the 12V thru a pot
> and speaker.
>
> The same is foru for all the transistors. but once you correct that
> it seems you just need to verify base voltage needed to drive the
> higher voltage.
>
> as it is now, I would worry about putting the higher voltage into the
> pins.
>
> Dave
>
>
>
>
> --- In basicstamps@yahoogroups.com, "captainconstructor"
> <captainconstructor@y...> wrote:
> > Hey all !
> >
> > This is all pretty new to me, but here goes.
> > I am looking for opinions/suggestions about the project that I am
> > working on (A Question and Answer display to be used for an annual
> > Fire Prevention Expo run by my firehouse.)
> >
> > I have uploaded the schematic, pcb layout, and source code
> associated
> > to this address:
> >
> > http://groups.yahoo.com/group/basicstamps/files/Quizboard/
> >
> > I am especially interested in comments on my output section design.
> > I am a little concerned with the coupling of 2 dissimilar voltage
> > levels (+5V regulated and +12V unregulated)and their effect on the
> > circuit.
> >
> > If you have a few moments to look over my design, I would appreciate
> > any advice that you could offer.
> >
> > Thanks
> > C.C.
>
>
> To UNSUBSCRIBE, just send mail to:
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