Hi, I'm using this (OPA134)
I've double checked the connections and measured the voltages directly at the input pins..
Have somehow fried the IC or have i just misunderstood something?
thanks for any help!
-Anthony
You haven't exactly described how you have it wired up. That might make a difference ...
**Of course. We need to see what you've done wrong. BTW: The 5 Volts available from a USB port is at the very low end of what is usable for that particular chip.
-- Trevor Wilson www.rageaudio.com.au
Yes. A schematic or description of how you are using it may help.
A photo of your breadboard setup is best and easiest way we can see exactly what's happening.
Ideally you should be using a comparator for this, like an LM311 for example.
Dave.
-- ================================================ Check out my Electronics Engineering Video Blog & Podcast: http://www.alternatezone.com/eevblog/
ok, a picture makes sense. But i can't get a clear one with my crappy camera phone even with flash.
I'll try a higher supply voltage but i read just over 5v from USB port and
5.00v exactly on the power supply pins of the IC.I can get a LM311 in a few days.
What i'm trying to achieve and how i'm doing it: perform an analogue to digital conversion on a sine wave signal with a max frequency of about 266Hz. Originally started with a dedicated ADC IC but at the highest rated clock speed the sample rate was still too slow for what i needed.
Then tried using DAC chip driven by a counter and connected to comparator to act as Analog-digital converter. For some reason the DAC chip outputted completely weird voltages (i've checked the counter outputs that pass to DAC chip as counter ic was clocked) so i've temporarily replaced DAC chip with a R/2R resistor network.
so i'm just left with weird op amp behavior
thanks for suggestions so far!
You don't have a real camera? Most likely a low light (indoors) problem, take it outdoors on a sunny day and try again.
What ADC would be too slow for 266Hz?
You are jumping through hoops doing it that way. Try a real ADC again.
What is reading the data and controlling this?, a microcontroller perhaps?
Dave.
-- --------------------------------------------- Check out my Electronics Engineering Video Blog & Podcast: http://www.alternatezone.com/eevblog/
On Tue, 4 Aug 2009 13:48:46 +1000, "Trevor Wilson" put finger to keyboard and composed:
... and the Common-Mode Voltage Range is (V?)+2.5 to (V+)?2.5.
- Franc Zabkar
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On Tue, 4 Aug 2009 21:31:10 +1000, "fuzzymonkey" put finger to keyboard and composed:
I think you need a device that goes rail-to-rail on the input side.
Maxim Micropower, Low-Voltage, UCSP/SC70, Rail-to-Rail I/O Comparators:
"The MAX985/MAX986/MAX989/MAX990/MAX993/MAX994 single/dual/quad micropower comparators feature low-voltage operation and rail-to-rail inputs and outputs. Their operating voltages range from 2.5V to
5.5V ..."Free samples:
Be aware that some comparators have open-collector or open-drain outputs which means you will need to add a pullup resistor.
- Franc Zabkar
-- Please remove one \'i\' from my address when replying by email.
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