# Shifting 3V3 to 5V

Discussion in 'Homework Help' started by lexected, Jul 22, 2014.

1. ### lexected Thread Starter New Member

Jul 8, 2014
3
0
Hello!

I've got a bit of a dumb question. I'm using LTSpice for simulation of simple shifter which takes 0V or 3.3V as input and gives 0V or 5V as output. Here's my scehmatic (the image is way too large): http://i62.tinypic.com/16jrjmw.jpg .

When doing simulation I view the voltage on R2 and it's -4.7V instead of +4.7V or +5V.
What am I doing wrong? What must be changed to get positive voltage on R2?

Thanks.

2. ### ericgibbs AAC Fanatic!

Jan 29, 2010
3,223
554
Hi lex,
I use this simple circuit for non inverting logic level shifting.

E

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3. ### ScottWang Moderator

Aug 23, 2012
5,425
854
1. Please upload your circuit to the forum of this website.
2. When you drawing the circuit, put the positive on the upside and put the negative on the downside is better.
3. Please refer to the following circuit of fig-07.

You can using the value of resistor you like.

4. ### lexected Thread Starter New Member

Jul 8, 2014
3
0
ericgibbs, ScottWang, thank you both for your answers.

Using batteries was my intention. I'm bit confused about the source-ground thing, I always used to connect ground to the negative terminal of battery. fig-07 was actually my source and I tried to remake it to use battery.

Can I freely connect Vcc to battery+ and gnd to battery- without doing anything wrong? If not, what can I use as ground? Some big piece of iron?

5. ### ericgibbs AAC Fanatic!

Jan 29, 2010
3,223
554
hi lex,
Ground/0V/Common are often used to mean the same thing.

If you use batteries for my level shifter , connect both Negatives together as the Common/0V line.

Scotts circuits are not level shifters, but 'driver circuits'

E

EDIT:
Look at this edited circuit that shows a 0V Comm, Ground

An 'Earth' connection is something different from Ground.

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6. ### ScottWang Moderator

Aug 23, 2012
5,425
854
That's a level shifter, and also a 'driver circuit', it depends on how you connecting the +Vcc to 3.3v,5V,9V,12V, and how the values of resistor you are using.

May 4, 2013
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