About function generator and multiplexer

Thread Starter

viraj.dali

Joined Oct 20, 2016
36
Hallo
I wanted some information regarding the function generator. I want to generate the signal of 5V/TTL from function generator. For that I have set the frequency as 1kHz, amplitude as 2.5V. Output is square signal. When I observe this signal on oscilloscope it shows me 5V square signal. But later, when I connect this signal to multiplexer input, then at the input pin of multiplexer shows voltage level of 2.5V.

I want to have 5V/TTL signal at the output of Multiplexer.
Please suggest some suggestion.

Thank you in Advance.
 

AnalogKid

Joined Aug 1, 2013
8,927
Without a schematic there is no way to narrow down the many possibilities to a single answer. Also, what is the multiplexer part number.

ak
 
Last edited:
It almost looks like your measuring amplitude wrong. +-2.5 V is 5 V p-p, but not 0-5V p-p.

The function generators I have used had a TTL output.

I'd throw together a logic FET and effectively a full up to your +5 and keep the output below Vgs Max.
For slower signals an optocoupler or even a transistor and the appropriate glue (resistors).
 

Reloadron

Joined Jan 15, 2015
5,776
Hallo
I wanted some information regarding the function generator. I want to generate the signal of 5V/TTL from function generator. For that I have set the frequency as 1kHz, amplitude as 2.5V. Output is square signal. When I observe this signal on oscilloscope it shows me 5V square signal. But later, when I connect this signal to multiplexer input, then at the input pin of multiplexer shows voltage level of 2.5V.

I want to have 5V/TTL signal at the output of Multiplexer.
Please suggest some suggestion.

Thank you in Advance.
What is the input impedance of your scope and what is the input impedance of your mux? Reading your MUX data sheet:
Supply voltage range, VCC −0.5 V to 4.6 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Input voltage range, VI (see Note 1) −0.5 V to 4.6 V
NOTES: 1. The input and output negative-voltage ratings may be exceeded if the input and output clamp-current ratings are observed.

It would appear you are over driving the MUX with 5 volts.

What impedance is your source (Function Generator) designed to work into? That should be labeled on the output connector. One of my function generators is designed to work into a 50 Ohm load. If I set it up working into 50 Ohms and then remove the load and look at the output it doubles.

Ron
 
Yes. I’m relatively new to LabVIEW and am kinda confused about the usage of the multiplexer. I’m using usb 2020 card which has 2 analog and 7 digital channel but for my project I need 8 channels which would read data from the surface. So I decided to use a multiplexer taht offer 16 analog channels. cd74hc4067 But I’m confused on how to use those analog channels. I made a mux subvi with the truth table in order to enable the channels. I create 4 digital outputs and connect it to the subvi to get the outcome channel but then I don’t knwo how to use the channel. I would appreciate any help
 

Reloadron

Joined Jan 15, 2015
5,776
This likely would have gone better if you started your own thread. The truth table is on page 2 of THIS DATA SHEET. Yes, you have 4 digital channels to address whichever channel you want. The data sheet covers switching specifications in detail. Less seeing a schematic of exactly what you plan to do this is as good as it gets and again, I suggest you start your own thread.

Ron
 
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