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'Parallel port current'
1999\11\11@225720 by Mike M

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hey guys i built a programmer to program 24lc32 eeproms, i wanted to know if the
parallel port would have enough current to supply power to operate the chip.  i
believe the 24lc32 needs a Vcc of 3ma at around 5v while its writing.  If not i
guess ill have to throw on a 9v battery and a 7805.

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1999\11\12@000936 by Richard Martin

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Theoretically the parallel port supplies (sources) _NO_ current
at 5V (or whatever is the precise voltage the logic is supplied).
So you will get _something_ less than 5V. How much less
(at a given current)  depends on the detailed design of the parallel
port silicon (which is pretty much unknown today). There are
programmers which power Atmel chips off several bussed
parallel port pins, but these (Atmel) chips can operate at reduced
voltages. Since you are likely to choose to use the battery and
regulator, I suggest you go ahead and add an e.g. 74HC244
or similar buffer inside the DB25 plug, as the Atmel 'dongle' does.
It will make things more predictable, and can serve as some
protection against dropping  a loose wire with a voltage that will
fry (at least part of ) your PC motherboard.
<The schematic for the Atmel 'dongle' seems to have vanished
from the Web?? But you can design your own singular pinouts.>

R.Martin

Mike M wrote:

> hey guys i built a programmer to program 24lc32 eeproms, i wanted to know if t
he parallel port would have enough current to supply

1999\11\12@050617 by Caisson

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> Van: Mike M <spam_OUTelektrikmanTakeThisOuTspamDYNAMITEMAIL.COM>
> Aan: .....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU
> Onderwerp: Parallel port current
> Datum: vrijdag 12 november 1999 4:50

Hi Mike,

> hey guys i built a programmer to program 24lc32 eeproms, i wanted to know
if
> the parallel port would have enough current to supply power to operate
the chip.
> i believe the 24lc32 needs a Vcc of 3ma at around 5v while its writing.
If not i
> guess ill have to throw on a 9v battery and a 7805.

I've got a 24C16 "programmer" here, that takes it's current from the
Printer-port.  I just wired 3 output-pins together thru BAT 85 diodes (0.3
volts voltage-drop).  Other parts are two  BAT 85 diodes to create two
Open-collector outputs (for SDA & SCL) , and two 10 K-ohm resistors as
pull-ups.  The whole "circuit" is build into a connector, just leaving 4
threads going to my "adapter" ( a simple IC-socket ).  It has not failed me
yet !

Regards,
 Rudy Wieser

1999\11\12@055633 by PerErik Klarenfjord

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{Quote hidden}

If you want the circuit i try to explain it for you.

/PEK

1999\11\12@082229 by Wagner Lipnharski

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Ok Mike, if this is for a single instalation, your computer and all, why
not just install a "Y" power connector at your PC I/O power supply cable
and then you can install a small terminal block outside with not only
+5Vdc (bunches of current available) but also +12V...?    All cpu fans
have those Y cables, so just look at the junk box.

There is a tendency to be afraid to mess with computer power supply, but
we are willing always to mess with the little and fragil voltage
generated by the parallel and serial driver chips... why is that?

PC's power supply are strong and some can stand a nice external short
circuit via 5ft #24 wire at +5Vdc without shutting down...  The worse
can happens is rebooting the PC, but if you fry a parallel port chip,
you be better buy another mother board or parallel port card.

Still afraid? ok, install a 1A fuse in the wire!

Wagner.

Mike M wrote:
>
> hey guys i built a programmer to program 24lc32 eeproms, i wanted to know if t
he parallel port would have enough current to supply power to operate the chip.
i believe the 24lc32 needs a Vcc of 3ma at around 5v while its writing.  If not
i guess ill have to throw on a 9v battery and a 7805.
>
> Send someone a cool Dynamitemail flashcard greeting!! And get rewarded.
> GO AHEAD! http://cards.dynamitemail.com/index.php3?rid=fc-41

1999\11\12@094405 by Mike M

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well i dont want to have to have wires sticking out of the pc all over the place
thats why.  I figured a nice simple card that just plugs in..running a y cable
from the internal supply to the outside will not look as clean.


On Fri, 12 Nov 1999 08:20:25 -0500 Wagner Lipnharski <wagnerlspamKILLspamEARTHLINK.NET> wro
te:
{Quote hidden}

the parallel port would have enough current to supply power to operate the chip.
 i believe the 24lc32 needs a Vcc of 3ma at around 5v while its writing.  If no
t i guess ill have to throw on a 9v battery and a 7805.
>>
>> Send someone a cool Dynamitemail flashcard greeting!! And get rewarded.
>> GO AHEAD! http://cards.dynamitemail.com/index.php3?rid=fc-41
>

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1999\11\12@095016 by Mike M

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>> I've got a 24C16 "programmer" here, that takes it's current from the
>> Printer-port.  I just wired 3 output-pins together thru BAT 85 diodes (0.3
>> volts voltage-drop).  Other parts are two  BAT 85 diodes to create two
>> Open-collector outputs (for SDA & SCL) , and two 10 K-ohm resistors as
>> pull-ups.  The whole "circuit" is build into a connector, just leaving 4
>> threads going to my "adapter" ( a simple IC-socket ).  It has not failed me
>> yet !
>>
>> I have allmost the same programmer which can program 24xxx but use the
>> seriell-port instead. It takes the current from the port. With some changes
>> it's a variant of the well known COM84-programmer which can program PIC16x84.
>> The software I use is PIP02.
>
>If you want the circuit i try to explain it for you.
>
>/PEK
>

Ive done the serial programmer writing the software for the parallel programmer
seemed easier to me so thats what i did.  But thanks anyway

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1999\11\12@095217 by Mike M

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Sounds like the best way to go thanks guys, sorry for all the replies : )

MikE

On Thu, 11 Nov 1999 21:12:43 -0800 Richard Martin <.....rmmartinKILLspamspam.....SERV.NET> wrote:
{Quote hidden}

the parallel port would have enough current to supply
>

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1999\11\13@165419 by miked

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>
> well i dont want to have to have wires sticking out of the pc all over
> the place thats why.  I figured a nice simple card that just plugs
> in..running a y cable from the internal supply to the outside will not
> look as clean.
>
>

+5V and Gnd are available on Game Ports and PS/2 ports.

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