Cleaning up a voltage

[Peter]

I have a voltage source that alternates between 2v and 7v. I want to
drive a logic level Mosfet with it, so I need the input to be either
0v or 5v. I can limit the high (not really necessary) with a zener,
but what is a SIMPLE way to make the 2v become 0v? I am worried that
the 2v will partially turn on the mosfet and overheat it.

 

[John Larkin]

On Mon, 28 Jul 2003 03:04:17 +0000 (UTC), "Costas Vlachos"
<c-X-vlachos@hot-X-mail.com> wrote:

"Peter" <pmolsen@one.net.au> wrote in message
news:6ba442b.0307271718.7a42412b@posting.google.com...
I have a voltage source that alternates between 2v and 7v. I want to
drive a logic level Mosfet with it, so I need the input to be either
0v or 5v. I can limit the high (not really necessary) with a zener,
but what is a SIMPLE way to make the 2v become 0v? I am worried that
the 2v will partially turn on the mosfet and overheat it.



Do this:

. 3 x 1N4148
.
. 2 - 7V o------->|-->|-->|---+-------o 0 - 5V
. |
. |
. .-.
. | |
. 10k | |
. '-'
. |
. |
. ===
. GND

Regards,
Costas

Right, with maybe a bypass cap across the diodes if mosfet off time is
important.

John

 

[Costas Vlachos]

"Peter" <pmolsen@one.net.au> wrote in message
news:6ba442b.0307271718.7a42412b@posting.google.com...

I have a voltage source that alternates between 2v and 7v. I want to
drive a logic level Mosfet with it, so I need the input to be either
0v or 5v. I can limit the high (not really necessary) with a zener,
but what is a SIMPLE way to make the 2v become 0v? I am worried that
the 2v will partially turn on the mosfet and overheat it.

Do this:

.. 3 x 1N4148
..
.. 2 - 7V o------->|-->|-->|---+-------o 0 - 5V
.. |
.. |
.. .-.
.. | |
.. 10k | |
.. '-'
.. |
.. |
.. ===
.. GND

Regards,
Costas
_________________________________________________
Costas Vlachos Email: c-X-vlachos@hot-X-mail.com
SPAM-TRAPPED: Please remove "-X-" before replying

 

[Baphomet]

That's why God made Schmitt triggers
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/schmitt.html

"Peter" <pmolsen@one.net.au> wrote in message
news:6ba442b.0307271718.7a42412b@posting.google.com...

I have a voltage source that alternates between 2v and 7v. I want to
drive a logic level Mosfet with it, so I need the input to be either
0v or 5v. I can limit the high (not really necessary) with a zener,
but what is a SIMPLE way to make the 2v become 0v? I am worried that
the 2v will partially turn on the mosfet and overheat it.

 

[Peter]

"Costas Vlachos" <c-X-vlachos@hot-X-mail.com> wrote in message news:<bg23rh$ja3$1@hercules.btinternet.com>...

Do this:

. 3 x 1N4148
.
. 2 - 7V o------->|-->|-->|---+-------o 0 - 5V
. |
. |
. .-.
. | |
. 10k | |
. '-'
. |
. |
. ===
. GND

Regards,
Costas

Thanks for the idea, but will it work with a Mosfet atached to the
output given that the gate is effectively infinite resistance? Will
the diodes still drop the voltage?