# DC Voltage Level Shifter

#### Beckalina

Joined Feb 17, 2009
3
Hi,

I'm working on an undergraduate project at the moment and have been asked to design a level shifter circuit. The world of electronics is a mystifying and confusing world for me, but I'm trying to learn, so I'd really appreciate some help with this task!

Basically I have two input DC voltages of 3.3V and 5V and I need to create a circuit where when the 3.3V input is on, the circuit has a 5V output, but when the 3.3V input is off, there's not output at all. My team leader has suggested a voltage level shifter and asked me to research it, but if anybody has any better ideas, those would be much appreciated!

As I said, I have no electronics experience at all, so finding this all a bit confusing but am ready and willing to learn!

#### eblc1388

Joined Nov 28, 2008
1,543
Basically I have two input DC voltages of 3.3V and 5V and I need to create a circuit where when the 3.3V input is on, the circuit has a 5V output, but when the 3.3V input is off, there's not output at all.

I think you meant you have two voltages of 3.3V and 0V(instead of 5V).

You want the circuit to output 5V if input is 3.3V and 0V if input is 0V. Is that right?

#### mik3

Joined Feb 4, 2008
4,846
Here is a simple one.

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#### Beckalina

Joined Feb 17, 2009
3
Hi, thanks for your reply, I'll have a look at that circuit tomorrow with my team leader and see if he thinks it will work. I've attached a diagram of the circuit he asked me to simulate in case that sheds any light on what I mean!

I'm 99% sure I meant what I said about the two inputs, but as I mentioned - I'm totally inexperienced in electronics!

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#### mik3

Joined Feb 4, 2008
4,846

Move resistors R2 and R4 between drain and Vcc.

#### Beckalina

Joined Feb 17, 2009
3
ok so i've attached a picture of the new circuit I've created - will this one work? between which points should i measure the voltage when i'm changing V2 between 0V and 3.3V?

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#### mik3

Joined Feb 4, 2008
4,846
Remove R2 and R3. Connect the source of the MOS to ground and its gate to the collector of Q1. Then put a 560 ohm resistor between the collector of Q1 and 5V. Finally, take your output between the drain of the MOS and ground. Your input voltage is V2.