0-5V square wave to sine wave with zero crossing?

I just tired a 22, 47, 100 and 150uF caps with no luck. This is starting to get discouraging.

Hmmm? The data sheet I'm looking at says, in Absolute Maximum Ratings...

Input Voltage -0.3VDC to +36VDC

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

If the sensor has three wire it IS a Hall Effect.

The signal is an open-collector output, so you will HAVE TO pull it up (usually about 1K ohm) to either 5 volts or (more often) to 12 volts.

What brand data sheet are you looking at? I'm looking at National's and I'm not seeing that to which you refer.

But that's all right, I've probably designed in more LM324's and LM339's than you are days old ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

It's likely that the original speed _indicator_ clips the sine VR signal anyway.

You might look into the _indicator_ specs.

What will likely work is a variation on Blogg's post, but I'd do 2x2 diodes (2 each in series, then back-to-back parallel) and add an R in series with the C. (Real men don't do ASCII... if it's not clear to you I can post a _real_ schematic on A.B.S.E ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

** Add one capacitor - stir well.

.......... Phil

The version I find DOESN'T have the "0" in the LM339 column, just for the LM2901 and LM3302.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

i think i was the one that told you to try a transformer your looking a sine wave, a transformer should suppress the fast slew/skew to give you a more rounded pulse.. it's just a throught. P.S. i think you stated that you needed a 10v P-P ?

--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

Jamie, That's on my list stuff to try, I'm just doing the easy stuff first. What type of transformer do you recommend? I need something with a decent level 10Vpp is just a random number i made up.

-Rich

Jim, Thanks for replying. I tired drawing out what you wrote but i couldn't figure it out. Could you please send me a schematic.

-Rich

Hello Jim,

I know it would work but the data sheet says 0V. Foot note 6 states that neither input shall be allowed more than 300mV below. However, that cannot be considered a guarantee that it will remain fully functional while below 0V. So, in a heavily regulated field you can't really do it. Until they change the data sheet or give it to you in writing. Which they don't. Been there, tried that, didn't fly...

Regards, Joerg

Hello Jim,

Yes, but proper circuit function is not guaranteed over the abs max ranges. All the abs max says is that it won't fry within the stated limits. For example, on the LM339 both V+ and Vin are allowed to 36V per abs max, single supply. If you supply it with 36V then the device is guaranteed not to function with Vin at 36V because its common mode range doesn't include the positive rail. You'd have to take V+ to 38V to do that, probably followed by a pop and a puff of smoke.

In regulated industries you can only go by what's under "Electrical Characteristics". And even there you cannot use the "Typ" columns but the circuit around the chip must tolerate any chip that is between "Min" and "Max".

Regards, Joerg

Hello Jim,

National. Page 4, input common-mode voltage range: Min 0V, max V+ minus

1.5V. Note 6 says 300mV but not that it will work properly down to that. (Yes, I know it will...)

I know that these are just legal technicalities but if you have the FDA and other agencies constantly breathing down your neck it's better to stick to the rules. If something goes wrong, and that can be totally unrelated (unit fall on someone's foot, whatever), those are the tiny things that lawyers may ask their expert witness EEs to go going looking for. Just to attack the design engineer's reputation.

In med electronics you've got to have it in writing. It's the same with other chips, like the MSP430. Looking at the graphs it is easy to see that they have 30ohm devices at the port pins. Yet TI specs 2mA as the limit (even in the abs max). So I called. "Yep, they can drive a lot more" ... "Could I have an email to that effect?" ... "Nope." So I didn't design it in.

It wasn't too many LM339's on my side. Main reason is that you can often do the same with a free 1/4th of an LM324 plus a diode if you need OC output.

But the number of LM324's shipped for production on my designs is quite huge. It's my staple amp. The sole reason is cost and the fact that it's input CM range includes the negative rail.

Regards, Joerg

Hello Jim,

Hmm..., mine does. Shows up first at the bottom on page 2, Electrical Characteristics, 4th row, 2nd columns:

Unless there is a special Arizona version of it ;-)

Page 4 of the online version actually doesn't have it on page 4. Must be a printing error because it is on hardcopies and also on the tables above it.

Regards, Joerg

Aha! You're fretting over Common Mode Voltage Range. I thought we were worrying over flame ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

I'll post a schematic at a URL so all can see.

What frequency range are we talking?

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

Lets see 8000 pluses per mile means if i want to go 60mph, one mile per min. So 8000/60=134 Hz but im always in a hurry so 134*2= 268Hz. Does that look right?

-Rich

Rich, I talked to my prof and he says the output voltage is not linear and the frequency is measured. With my DMM i measured around 8Vrms at sensor, I was probably going 20mph. I havent looked at the reluctor sensor on a scope since i have no way of simulating the moving teeth and i have no way of getting a scope into the car.

-Rich

Well, you're never going to get anywhere if you're just making stuff up. What signal is the gauge actually looking for? What is the actual output of the sensor you're trying to simulate? Have you looked at it on a scope?

Good Luck, Rich