Voltage Shifter

M

mlt57sooner

New Member

• Apr 21, 2005

• #1

I am actually pulsing a 555 timer with amicroprossor to give burst of 40 kHz. I would like to pulse the 555 with 12 volts instead of the five that comes out of the processor. I would like to know of a simple way to turn the 5 volts into 12 volts. The voltage shifter circuit also needs to be able to respond to the fast pulses very well. Thanks

 

David Bridgen

Member

• Apr 21, 2005

• #2

If you don't need to preserve the polarity of the pulse a single transistor will do the job.

If you do want to keep the same polarity you will need two transistors.

 

Phasor

Member

• Apr 21, 2005

• #3

I assume you have the 555 in astable configuration? You can connect the microprocessor output directly to the reset pin of 555 (pin 4). A high signal enables the timer, a low signal disables it.

(The 2khz signal in the screenshot below represents the microprocessor output)

edit: Just realised this is ALMOST my 555th post. That would have been so appropriate...

 

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M

mlt57sooner

New Member

• Apr 21, 2005

• #4

Transistors?

How would I arrange the transistors? Do you have any example schematics? As for the second reply I have already generated the signal I want I just need it to have a larger pk-pk value. Thanks

 

Phasor

Member

• Apr 21, 2005

• #5

mlt57sooner said:

I am actually pulsing a 555 timer with amicroprossor to give burst of 40 kHz. I would like to pulse the 555 with 12 volts instead of the five that comes out of the processor.

Click to expand...

In that case, I'm not quite sure what you are doing exactly. Got a schematic of your current set-up?

 

M

mlt57sooner

New Member

• Apr 21, 2005

• #6

Set-up

I just have the 555 set up to produce a 40 kHz signal and I am turning the 555 on and off with the microprossor. I know that reset lead is supposed to be used to pulse the 555 but I could not get a clean pulse out of the 555 using the reset lead. So I would like to turn the 555 on and off using 12 volts instead of 5 volts.

 

Phasor

Member

• Apr 21, 2005

• #7

I think this is what Mr Bridgen was suggesting:
(again, the 2khz signal represent the uP output)

 

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David Bridgen

Member

• Apr 22, 2005

• #8

What a strange thing to do Phasor.

All your circuit does is apply a 1k load to the 555 2,000 times a second.


No. What I meant is something like this:

 

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Phasor

Member

• Apr 22, 2005

• #9

David Bridgen said:

What a strange thing to do Phasor.

Click to expand...

Ah yes, what was I thinking?? As Ron H would put it, I had a Brain Fart.

 

David Bridgen

Member

• Apr 23, 2005

• #10

Yes, I have them myself.