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Sci.Electronics.Basics -> lab power supply
There are 14 messages in this thread.
You are currently looking at messages 1 to 14.
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Author: dunsscoto2@gmail.comDate: 17:18 20-08-07
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hi to all
i'm an italian electronics hobbyist,
i'm sorry for my bad english :(
in this holiday i try to build my first lab fully adjustable power
supply unit
i try to hack the scheme at pag.8 of the datasheet of the lm317
http://www.ortodoxism.ro/datasheets/nationalsemiconductor/DS009063.PDF
for add the negative section,
the tracking voltage mode,
the transistor for increase the output current,
and a costant current output protection..
i ' ve implemented 5V reference due to start the regulation from 0V
instead of 1.2V (normal limit of an LM317)
i would like to use an lm705 for the 5 volt reference using this
voltage for an ausiliary power supply for TTL boards
i obtained this basic principle scheme , not yet dimensionated
i will have an opinion about eventual problem or improvements
http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7.pdf
thanks to all for the patience
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Author: ehsjrDate: 00:59 21-08-07
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dunsscoto2@gmail.com wrote:
> hi to all
> i'm an italian electronics hobbyist,
> i'm sorry for my bad english :(
> in this holiday i try to build my first lab fully adjustable power
> supply unit
> i try to hack the scheme at pag.8 of the datasheet of the lm317
> http://www.ortodoxism.ro/datasheets/nationalsemiconductor/DS009063.PDF
> for add the negative section,
> the tracking voltage mode,
> the transistor for increase the output current,
> and a costant current output protection..
> i ' ve implemented 5V reference due to start the regulation from 0V
> instead of 1.2V (normal limit of an LM317)
> i would like to use an lm705 for the 5 volt reference using this
> voltage for an ausiliary power supply for TTL boards
> i obtained this basic principle scheme , not yet dimensionated
> i will have an opinion about eventual problem or improvements
> http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7.pdf
> thanks to all for the patience
>
Your bridge rectifier is wrong.
Ed
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Author: dunsscoto2@gmail.comDate: 06:12 21-08-07
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On 21 Ago, 06:59, ehsjr <eh...@bellatlantic.net> wrote:
> dunssco...@gmail.com wrote:
> > hi to all
> > i'm an italian electronics hobbyist,
> > i'm sorry for my bad english :(
> > in this holiday i try to build my first lab fully adjustable power
> > supply unit
> > i try to hack the scheme at pag.8 of the datasheet of the lm317
> >http://www.ortodoxism.ro/datasheets/nationalsemiconductor/DS009063.PDF
> > for add the negative section,
> > the tracking voltage mode,
> > the transistor for increase the output current,
> > and a costant current output protection..
> > i ' ve implemented 5V reference due to start the regulation from 0V
> > instead of 1.2V (normal limit of an LM317)
> > i would like to use an lm705 for the 5 volt reference using this
> > voltage for an ausiliary power supply for TTL boards
> > i obtained this basic principle scheme , not yet dimensionated
> > i will have an opinion about eventual problem or improvements
> >http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7.pdf
> > thanks to all for the patience
>
> Your bridge rectifier is wrong.
>
> Ed
LOL!!
you have reason!! :)
excuse me
I have placed it without thinking
I correct the outline immediately
thanks ehsjr
other problems relative the current control?
that one is the part too much complicated for me
have you got an idea for join the two current controll into one?
the updated scheme:
http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7B.pdf
thanks for the help
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Author: dunsscoto2@gmail.comDate: 14:30 21-08-07
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On 21 Ago, 12:12, "dunssco...@gmail.com" <dunssco...@gmail.com> wrote:
> On 21 Ago, 06:59, ehsjr <eh...@bellatlantic.net> wrote:
>
>
>
> > dunssco...@gmail.com wrote:
> > > hi to all
> > > i'm an italian electronics hobbyist,
> > > i'm sorry for my bad english :(
> > > in this holiday i try to build my first lab fully adjustable power
> > > supply unit
> > > i try to hack the scheme at pag.8 of the datasheet of the lm317
> > >http://www.ortodoxism.ro/datasheets/nationalsemiconductor/DS009063.PDF
> > > for add the negative section,
> > > the tracking voltage mode,
> > > the transistor for increase the output current,
> > > and a costant current output protection..
> > > i ' ve implemented 5V reference due to start the regulation from 0V
> > > instead of 1.2V (normal limit of an LM317)
> > > i would like to use an lm705 for the 5 volt reference using this
> > > voltage for an ausiliary power supply for TTL boards
> > > i obtained this basic principle scheme , not yet dimensionated
> > > i will have an opinion about eventual problem or improvements
> > >http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7.pdf
> > > thanks to all for the patience
>
> > Your bridge rectifier is wrong.
>
> > Ed
>
> LOL!!
> you have reason!! :)
> excuse me
> I have placed it without thinking
> I correct the outline immediately
> thanks ehsjr
> other problems relative the current control?
> that one is the part too much complicated for me
> have you got an idea for join the two current controll into one?
> the updated scheme:http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7B.pdf
> thanks for the help
I have found an other error of distraction
and I have update the schematics
please criticize it :)
http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7C.pdf
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Author: Paul E. SchoenDate: 17:27 22-08-07
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<dunsscoto2@gmail.com> wrote in message
news:1187721056.752932.204730@19g2000hsx.googlegroups.com...
> On 21 Ago, 12:12, "dunssco...@gmail.com" <dunssco...@gmail.com>
wrote:
>> On 21 Ago, 06:59, ehsjr <eh...@bellatlantic.net> wrote:
>>
>>
>>
>> > dunssco...@gmail.com wrote:
>> > > hi to all
>> > > i'm an italian electronics hobbyist,
>> > > i'm sorry for my bad english :(
>> > > in this holiday i try to build my first lab fully adjustable power
>> > > supply unit
>> > > i try to hack the scheme at pag.8 of the datasheet of the lm317
>> > >http://www.ortodoxism.ro/datasheets/nationalsemiconductor/DS009063.PDF
>> > > for add the negative section,
>> > > the tracking voltage mode,
>> > > the transistor for increase the output current,
>> > > and a costant current output protection..
>> > > i ' ve implemented 5V reference due to start the regulation from
>> > > 0V
>> > > instead of 1.2V (normal limit of an LM317)
>> > > i would like to use an lm705 for the 5 volt reference using this
>> > > voltage for an ausiliary power supply for TTL boards
>> > > i obtained this basic principle scheme , not yet dimensionated
>> > > i will have an opinion about eventual problem or improvements
>> > >http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7.pdf
>> > > thanks to all for the patience
>>
>> > Your bridge rectifier is wrong.
>>
>> > Ed
>>
>> LOL!!
>> you have reason!! :)
>> excuse me
>> I have placed it without thinking
>> I correct the outline immediately
>> thanks ehsjr
>> other problems relative the current control?
>> that one is the part too much complicated for me
>> have you got an idea for join the two current controll into one?
>> the updated
>> scheme:http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7B.pdf
>> thanks for the help
>
>
> I have found an other error of distraction
> and I have update the schematics
> please criticize it :)
> http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7C.pdf
>
I think something is wrong with the +5 VDC supply. I'm not sure what is the
purpose of Q5 and Q6, and the bases tie to each other, but nowhere else.
Also, what is the raw DC voltage of +VCC and -VCC, and what is the
specification of the supply? It appears to be something like 0-15 VDC at
maybe 2-5 amperes, and the 7805 will provide 5 VDC at about 1 ampere. But
if its input is 20 VDC, it will dissipate 15 watts. And the other series
pass transistors will dissipate more than that. Also, the +VCC and -VCC
connect to the power supply of the op amps, which are only rated a maximum
of +/- 16 or 18 VDC.
It looks like the circuit is overly complicated for what is needed, and I
think there may be other problems. This could be a good project for
simulation using LTSpice.
I'd probably design it using a PIC!
Paul
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Author: Jonathan KirwanDate: 18:04 22-08-07
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On Tue, 21 Aug 2007 11:30:56 -0700, "dunsscoto2@gmail.com"
<dunsscoto2@gmail.com> wrote:
><snip>
>I have found an other error of distraction
>and I have update the schematics
>please criticize it :)
>http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7C.pdf
Spend a little time discussing your small +5V design near the bottom.
In particular, where the more positive side of it connects and I'm
also curious about the roles of Q5 and Q6 and R24 and R25 in the
context of the 7805.
Jon
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Author: dunsscoto2@gmail.comDate: 18:36 22-08-07
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On 22 Ago, 23:27, "Paul E. Schoen" <pst...@smart.net> wrote:
> <dunssco...@gmail.com> wrote in message
>
> news:1187721056.752932.204730@19g2000hsx.googlegroups.com...
>
>
>
> > On 21 Ago, 12:12, "dunssco...@gmail.com"
<dunssco...@gmail.com> wrote:
> >> On 21 Ago, 06:59, ehsjr <eh...@bellatlantic.net> wrote:
>
> >> > dunssco...@gmail.com wrote:
> >> > > hi to all
> >> > > i'm an italian electronics hobbyist,
> >> > > i'm sorry for my bad english :(
> >> > > in this holiday i try to build my first lab fully adjustable
power
> >> > > supply unit
> >> > > i try to hack the scheme at pag.8 of the datasheet of the lm317
> >> >
>http://www.ortodoxism.ro/datasheets/nationalsemiconductor/DS009063.PDF
> >> > > for add the negative section,
> >> > > the tracking voltage mode,
> >> > > the transistor for increase the output current,
> >> > > and a costant current output protection..
> >> > > i ' ve implemented 5V reference due to start the regulation
from
> >> > > 0V
> >> > > instead of 1.2V (normal limit of an LM317)
> >> > > i would like to use an lm705 for the 5 volt reference using this
> >> > > voltage for an ausiliary power supply for TTL boards
> >> > > i obtained this basic principle scheme , not yet dimensionated
> >> > > i will have an opinion about eventual problem or improvements
> >> > >http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7.pdf
> >> > > thanks to all for the patience
>
> >> > Your bridge rectifier is wrong.
>
> >> > Ed
>
> >> LOL!!
> >> you have reason!! :)
> >> excuse me
> >> I have placed it without thinking
> >> I correct the outline immediately
> >> thanks ehsjr
> >> other problems relative the current control?
> >> that one is the part too much complicated for me
> >> have you got an idea for join the two current controll into one?
> >> the updated
> >> scheme:http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7B.pdf
> >> thanks for the help
>
> > I have found an other error of distraction
> > and I have update the schematics
> > please criticize it :)
> >http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7C.pdf
>
> I think something is wrong with the +5 VDC supply. I'm not sure what is the
> purpose of Q5 and Q6, and the bases tie to each other, but nowhere else.
when r108*imax it becomes approximately equal to the Q26 Vbe,
Q26 is turned on ,it short circuit R109 and then switch off Q25 and it
limits therefore the output current
i copy it :)
http://www.ortodoxism.ro/datasheets/fairchild/LM7805.pdf
pag.23 fig.13
> Also, what is the raw DC voltage of +VCC and -VCC, and what is the
> specification of the supply?
:) this is a problem.. i have may transforma at home
but no time for searching the right one to use
> It appears to be something like 0-15 VDC at
> maybe 2-5 amperes,
yes i add the 5v regulator for force the zero volt
transistors hold 5A but i don't have choose the transformer yet
>and the 7805 will provide 5 VDC at about 1 ampere. But
> if its input is 20 VDC, it will dissipate 15 watts.
I suppose that I will use an other transformer
> And the other series
> pass transistors will dissipate more than that. Also, the +VCC and -VCC
> connect to the power supply of the op amps, which are only rated a maximum
> of +/- 16 or 18 VDC.
this is the greater limitation but i don't know how to do otherwise
>
> It looks like the circuit is overly complicated for what is needed, and I
> think there may be other problems.
for having complete protection against the short circuits voltage
tracking
and currente regulation I do not see other possibilities :(
>This could be a good project for
> simulation using LTSpice.
i try but seem that not exist a model for lm137,
and I have problems when I simulate the single part with the
operational
the simulation of the circuit does not want to converge
i'm not very expert with spice
>
> I'd probably design it using a PIC!
a pic?
how?
controlling the levels with the dac?
and the sensing with the adc?
is not a bad idea
therefore you could use a lcd
but you would have to write the software and
to the end you would only eliminate the three opamp..
now my big problem it's to group the
two current regulation at the same one
I thought to use the opamp advanced
>
> Paul
many thanks for the answer!
I have corrected the scheme newly,
led and the diode in the negative part was inverted
this is the new scheme:
http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7D.pdf
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Author: Jonathan KirwanDate: 18:53 22-08-07
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On Wed, 22 Aug 2007 15:36:31 -0700, "dunsscoto2@gmail.com"
<dunsscoto2@gmail.com> wrote:
>> I think something is wrong with the +5 VDC supply. I'm not sure what is the
>> purpose of Q5 and Q6, and the bases tie to each other, but nowhere else.
>when r108*imax
r108?
>it becomes approximately equal to the Q26 Vbe,
Q26?
>Q26 is turned on ,it short circuit R109
R109?
>and then switch off Q25
Q25?
>and it limits therefore the output current
>i copy it :)
>http://www.ortodoxism.ro/datasheets/fairchild/LM7805.pdf
>pag.23 fig.13
Yes... but... where did you get your value for 1k for R24 (that's waht
appears on the schematic you posted latest), which corresponds to Rsc
on the datasheet page? What figure are you using as the short circuit
current limit? And you show 1k for R25, when the datasheet's
corresponding R1 is 3 ohms? Why?
Jon
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Author: dunsscoto2@gmail.comDate: 19:01 22-08-07
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On 23 Ago, 00:04, Jonathan Kirwan <jkir...@easystreet.com> wrote:
> On Tue, 21 Aug 2007 11:30:56 -0700, "dunssco...@gmail.com"
>
> <dunssco...@gmail.com> wrote:
> ><snip>
> >I have found an other error of distraction
> >and I have update the schematics
> >please criticize it :)
> >http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7C.pdf
>
> Spend a little time discussing your small +5V design near the bottom.
> In particular, where the more positive side of it connects and I'm
> also curious about the roles of Q5 and Q6 and R24 and R25 in the
> context of the 7805.
>
> Jon
the necessity of the +5V is given from the problem that introduces the
two regolators
to supply 1,2 volt in place of 0 when refered to the ground.
In the schemeI had not still connected the regolator of the +5
because I was estimating to connect it on a transformer to part,
I would have intentional to use the same one but thinking that it
would have been revealed useful
to have a local power source for feeding logical TTL (that they
consume a lot current)
I have preferred to connect it to a transformer to part
i copy it from
http://www.ortodoxism.ro/datasheets/fairchild/LM7805.pdf
pag.23 fig.13
but I am stupid and have mistaken to copy! lol!
sorry!
me of I was not shrewed not even when I have tried to explain the
outline to Paul!
excused! the problem is that in Italy it is late night :D
and I am distracted of nature
i correct the scheme:
http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7D.pdf
many thanks!
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Author: dunsscoto2@gmail.comDate: 19:04 22-08-07
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On 23 Ago, 01:01, "dunssco...@gmail.com" <dunssco...@gmail.com> wrote:
> On 23 Ago, 00:04, Jonathan Kirwan <jkir...@easystreet.com> wrote:
>
> > On Tue, 21 Aug 2007 11:30:56 -0700, "dunssco...@gmail.com"
>
> > <dunssco...@gmail.com> wrote:
> > ><snip>
> > >I have found an other error of distraction
> > >and I have update the schematics
> > >please criticize it :)
> > >http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7C.pdf
>
> > Spend a little time discussing your small +5V design near the bottom.
> > In particular, where the more positive side of it connects and I'm
> > also curious about the roles of Q5 and Q6 and R24 and R25 in the
> > context of the 7805.
>
> > Jon
>
> the necessity of the +5V is given from the problem that introduces the
> two regolators
> to supply 1,2 volt in place of 0 when refered to the ground.
> In the schemeI had not still connected the regolator of the +5
> because I was estimating to connect it on a transformer to part,
> I would have intentional to use the same one but thinking that it
> would have been revealed useful
> to have a local power source for feeding logical TTL (that they
> consume a lot current)
> I have preferred to connect it to a transformer to part
> i copy it fromhttp://www.ortodoxism.ro/datasheets/fairchild/LM7805.pdf
> pag.23 fig.13
> but I am stupid and have mistaken to copy! lol!
> sorry!
> me of I was not shrewed not even when I have tried to explain the
> outline to Paul!
> excused! the problem is that in Italy it is late night :D
> and I am distracted of nature
> i correct the scheme:http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE7D.pdf
> many thanks!
http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE8.pdf
excused me still
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Author: Jonathan KirwanDate: 19:38 22-08-07
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On Wed, 22 Aug 2007 16:04:39 -0700, "dunsscoto2@gmail.com"
<dunsscoto2@gmail.com> wrote:
><snip>
>http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE8.pdf
>excused me still
I see the tie-in, now. That's a beginning. But what about R24 and
R25?? Exactly how did you calculate their values? What is the short
circuit current limit you desire, here?
I roughly calculate hundreds of microamps and I have to imagine that
the 7805 can handle that without any outboard BJTs floating about. And
that if you really do want to limit the current to that tiny level,
the circuit isn't going to do it because all it does is route the
excess current via Q6 and then the 7805, neither of which will 'know'
anything about the limits set up by R24 to limit what bypasses the
7805 via Q5. It's just shunted aside R25 and R24 + Q5 and back into
the 7805 to hit its own internal limits, based on temperature and/or
otherwise, instead. Do you agree?
Jon
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Author: dunsscoto2@gmail.comDate: 20:42 22-08-07
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On 23 Ago, 01:38, Jonathan Kirwan <jkir...@easystreet.com> wrote:
> On Wed, 22 Aug 2007 16:04:39 -0700, "dunssco...@gmail.com"
>
> <dunssco...@gmail.com> wrote:
> ><snip>
> >http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE8.pdf
> >excused me still
>
> I see the tie-in, now. That's a beginning. But what about R24 and
> R25?? Exactly how did you calculate their values? What is the short
> circuit current limit you desire, here?
r24 and r25 still they have not been calculates to you
1K it is the value of default of orcad
I still do not know that transistor I will use for Q5
>
> I roughly calculate hundreds of microamps and I have to imagine that
> the 7805 can handle that without any outboard BJTs floating about. And
> that if you really do want to limit the current to that tiny level,
> the circuit isn't going to do it because all it does is route the
> excess current via Q6 and then the 7805, neither of which will 'know'
> anything about the limits set up by R24 to limit what bypasses the
> 7805 via Q5. It's just shunted aside R25 and R24 + Q5 and back into
> the 7805 to hit its own internal limits, based on temperature and/or
> otherwise, instead. Do you agree?
i understood.. you have reason
this is very very beautifull http://digilander.libero.it/i2viu/curlimit.gif
but an other lm317..
I will try to search an other solution
wath do you think about the other part?
the operational can work?
i think that I will have to adjust some resistore value in the opamp
schematic part but i do it under final testing
have you got an idea on how to group the
two current regulation at the same one?
thanks for the patienz jon
>
> Jon
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Author: dunsscoto2@gmail.comDate: 21:02 22-08-07
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On 23 Ago, 01:38, Jonathan Kirwan <jkir...@easystreet.com> wrote:
> On Wed, 22 Aug 2007 16:04:39 -0700, "dunssco...@gmail.com"
>
> <dunssco...@gmail.com> wrote:
> ><snip>
> >http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE8.pdf
> >excused me still
>
> I see the tie-in, now. That's a beginning. But what about R24 and
> R25?? Exactly how did you calculate their values? What is the short
> circuit current limit you desire, here?
>
> I roughly calculate hundreds of microamps and I have to imagine that
> the 7805 can handle that without any outboard BJTs floating about. And
> that if you really do want to limit the current to that tiny level,
> the circuit isn't going to do it because all it does is route the
> excess current via Q6 and then the 7805, neither of which will 'know'
> anything about the limits set up by R24 to limit what bypasses the
> 7805 via Q5. It's just shunted aside R25 and R24 + Q5 and back into
> the 7805 to hit its own internal limits, based on temperature and/or
> otherwise, instead. Do you agree?
>
> Jon
creed that I will use one solution similar to this
for the 5V protection:
http://web.tiscali.it/i2viu/electronic/protez98.gif
me he seems good not?
this other solution is brilliant:
http://web.tiscali.it/i2viu/electronic/prot99.gif
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Author: dunsscoto2@gmail.comDate: 18:48 23-08-07
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On 23 Ago, 01:38, Jonathan Kirwan <jkir...@easystreet.com> wrote:
> On Wed, 22 Aug 2007 16:04:39 -0700, "dunssco...@gmail.com"
>
> <dunssco...@gmail.com> wrote:
> ><snip>
> >http://dunsscoto2.googlepages.com/SCHEMATIC1_PAGE8.pdf
> >excused me still
>
> I see the tie-in, now. That's a beginning. But what about R24 and
> R25?? Exactly how did you calculate their values? What is the short
> circuit current limit you desire, here?
>
> I roughly calculate hundreds of microamps and I have to imagine that
> the 7805 can handle that without any outboard BJTs floating about. And
> that if you really do want to limit the current to that tiny level,
> the circuit isn't going to do it because all it does is route the
> excess current via Q6 and then the 7805, neither of which will 'know'
> anything about the limits set up by R24 to limit what bypasses the
> 7805 via Q5. It's just shunted aside R25 and R24 + Q5 and back into
> the 7805 to hit its own internal limits, based on temperature and/or
> otherwise, instead. Do you agree?
>
> Jon
I am trying to plan and to simulate my new protection:
http://groups.google.it/group/sci.electronics.basics/browse_thread/thread/d4cd355e2e84bb
5a/21ffec1f40800100#21ffec1f40800100
with circuit foldback protection and pass transistor
i think that I will use that for the +5V
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