Sensor problem....

Thread Starter

Lithos

Joined Sep 10, 2011
14
Hello!
I am embarrassed because I had this thread for a long time and I didn't respond...
Sorry for that as I was abroad for a long time...
Finally I managed to put this into an oscilloscope for finding out input and output signals.
So this is what I came out with:


SgtWookie, helped me a lot with the previous one, so I am counting on him :)
One thing I want to say is that I want the output voltage to be managed by a capacitor (to avoid ICs), and the circuit can be more simple.
I am trying to use basic components as resistors, capacitors etc for this...

Any help would be accepted!
 

wayneh

Joined Sep 9, 2010
16,398
It's not clear whether the the input and output are linked, though I assume that is your goal. What logic/condition produces the output?
 

Thread Starter

Lithos

Joined Sep 10, 2011
14
Of course and they are linked, as you can see on the bottom graph...
When I open the switch the input signal in the graph, pass through the "box" and the box creates the output that I want to emulate...
If the output is like the output signal in the graph, then the sensor doesn't return fault, if it has another output I get the error...
 

joeyd999

Joined Jun 6, 2011
4,410
You cannot get the linear response you are looking for with just Rs and Cs. You need a constant current integrator, usually using an op amp.

You could use two current sources through a digitally controlled analog switch, but that still violates your 'no IC' requirement.

EDIT: Also, your ramp waveform is not synchronized with your original squarewave input. This 'non-linear' (i.e. output frequency fundamental != input frequency fundamental) transformation cannot be done with passive components.
 

SgtWookie

Joined Jul 17, 2007
22,210
I really don't have anything more to add to joeyd999's statements, as he's correct.

I gave you an opamp solution in the other thread, but that was a straight-line solution; this one would be different.

I am in the hospital recovering from heart bypass surgery. I don't have a "real" computer available to work the problem on. Perhaps someone else will assist you.

Lastly, you sent me an off-line E-mail with bad links to this thread, and no way to reply to your Email as you have E-mail turned off. I'm going to have a Moderator turn your E-mail and PM's on to prevent that annoyance to another member.
 

Thread Starter

Lithos

Joined Sep 10, 2011
14
I wish you well recovery SgtWookie!
Sorry for the inconvenience I didn't saw your signature about PMs...
I will try with op-amps...
 

SgtWookie

Joined Jul 17, 2007
22,210
I wish you well recovery SgtWookie!
Thank you.

Sorry for the inconvenience I didn't saw your signature about PMs...
If it is a thread that I have already participated in, and that more information later provided hasn't been acted on by myself over a period of sevearl days, then a PM to request a look at a given thread would be warranted. I wasn't complaining about your current PM. What I found really annoying, is that the link you provided to the thread was incorrect, and I could neither PM nor E-mail you to find out what you were talking about.

[/QUOTE]I will try with op-amps...[/QUOTE]

Using proper opamps will be helpful to getting a good start. However, the kind of response you are looking for is not a straight 1:1 correlation - you will need to use more than just op-amps with passive componenets.
 

Thread Starter

Lithos

Joined Sep 10, 2011
14
I think that the input acts as a trigger to an internal circuit that is powered through the source of 5 Volts.
So I am thinking using the source of 5Volts, pass it through a voltage divider to 3.5 Volts and then try to decrease and increase the voltage.
Also I suspect that the output timing doesn't matter the sensor, but just the lower (0Volts) and upper (3.5Volts)...:confused:
 

Thread Starter

Lithos

Joined Sep 10, 2011
14
What op-amp should I put, if I have to use this DC Voltage?



I also want the op-amp to be cheap and easy to find....
 

Thread Starter

Lithos

Joined Sep 10, 2011
14
The power supply is a PIECEWISE_LINEAR_VOLTAGE (Multisim)
And signal timings are 150ms, for fast simulation results...



But when I use an LMC6484AIN, all is normal...
 
Last edited:

Georacer

Joined Nov 25, 2009
5,182
Multisim has been caught before giving wrong results, for example driving the output of a 741 rail-to-rail. Maybe it's a bug.

Someone else might have a better suggestion.
 
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