Voltage Lever Shifter of PIC PI

[goldfinder]

Anyone know of a way to shift a -10v to 0v pulse to a 0v to 5v pulse. I have converted a 555 PI detector to a PIC driven detector with current capability to detect a 1 OZ gold coin at 3 feet in the air. I want to run the signal into another PIC to do some DSP and increase the depth detectability. I have scoured the opto-isolators and they all require about 1.5 volt input and obviously I am about 10x too high. Another possibility is to reduce the signal level. Or redesign the output section which I am loath to do.

Any help would be greatly appreciated.
Goldfinder

[Muntari]

Hi Goldfinder,

If you are looking to shift transmit pulse signals from -10 to +5v/0v then perhaps this little circuit will help. the 4050 is essentially meant for level shifting but must be AC coupled for your job.

You don't need the square up circuit if your logic already has it. The circuit is good from a few Hz up to 20-50kHz but beware of phase shift from input to output. Choosing the capacitor is a matter of pulse width and frequency range.

It does work and while not the only way, it is simple and cheap enough.
If I may ask, what is the reason for coupling the pulse back to another MPU?
Is this for sync signals?

Hope this helps.

regards

Brian K

[goldfinder]

Many Thanks

Thanks for your inputs. However, I found a way to change the input pulse to 0 to +10, then simply put the pulse into an opamp running a plus or minus 5. The resultant output is 0 to +5.

Goldfinder

[Carl-NC]

The simplest solution is to use an NPN level shifter. One NPN, and 2 resistors.

[Muntari]

Hi Goldfinder,

Reading your second post , I can see you are looking for level changing your recieve signal. Of course, the circuit I posted is useless for that. I was of the impression you were looking to change transmit pulse levels...stupid me.

Ok at least you have found a way that suits.


Cheers

Brian K

[goldfinder]

Carl - ? re NPN level shifter

HI Carl,
Thanks for a great site. Lots of good info re THing. Its a great service for all us wannabe treasure finders.

In regard to your post on the NPN level shifter. Is this a simple NPN transistor plus a couple of resistors or what. Please elucidate w/ part number and a circuit diagram of an internet address that describes this. I checked GOOGLE before ever posting and found no good solution.

Thanks in advance!
Goldfinder

[Carl-NC]

Below is the NPN level shifter I was thinking of. It is rather grungy, and a little non-linear, but would work just fine for converting a logic pulse.

But it seems you might have wanted to convert an analog signal, not a digital pulse. So the second circuit would be more suitable.

- Carl

[diggerbarns]

So you have -Batt +batt this can be 10/12v. so its -12 to 0v in respect to 0v you need a +5 and -5 why not then anchor your pics to -12 and have a +5v with respect to - 12 just to drive the pics. If you look at the Goldpic by Trevor Hill you will see how to drive from the pic via one transistor and two resistors. Driving to the pic can be done with a device LM393 N, this has an open collector output that can be tied to your +5v digital supply.

When you have worked it all out post it here.

[Unregistered]

level shifter

I used an NPN transistor as Carl shows to do just what you are doing. Connecting up a 5V PIC to the coil pulsing circuit. It worked just fine.
Boattow

[goldfinder]

Thanks for your inputs

I used a version of Carl's NPN opamp. Many thanks. I started a new thread for you electronic geniuses. Have a go at that please.
Best 2 U All,
Goldfinder