we are using the arduino uno board
we added a Bluetooth to our project
our project is about to make a wearable alcohol sensor to measure the alcohol level in your body.
here is the info of the sensor :
Is 741 OP AMP can be used in this circuits ? if yes , what should be the bias voltage ?
Probably. What bias voltage are you referring to? Please provide a link to information about the sensor.
I'd take a stab at saying No.
The '741 needs + and - supplies, something like a single-rail LM358 might be a better bet and happens to match the pinout of that diagram.
Yours,
TonyWilk
TonyWilk:
I'd take a stab at saying No.The '741 needs + and - supplies, something like a single-rail LM358 might be a better bet and happens to match the pinout of that diagram.
Yours,
TonyWilk
Bzzzt. Wrong. The 741 can be used in single supply configuration.
aarg:
Bzzzt. Wrong. The 741 can be used in single supply configuration.
Ok, yes... stuff >20v on it and you can use it single-rail, but hardly something to recommend these days.
Still, I am jumping the gun somewhat - not knowing anything yet about the context.
Yours,
TonyWilk
zakariaalmalki:
Is 741 OP AMP can be used in this circuits ? if yes , what should be the bias voltage ?
What is the supply voltage?
What is the sensor?
Why would you choose a 50 year old opamp?
If you describe what you are trying to do, we will be able to help you choose the best approach,
its not clear that this circuit is useful to you without knowing all the details of your hardware
and what you want to do with it.
Hi,
The 741 can be used in single supply configuration.
I used 741's with +12V and biased to 1/2 (6v) for audio amplifiers back in 1975. It works OK.
The 358 is a better choice today but I think you'd want to bias it differently? If there is existing PC board the 741 might be best. Or a modern chip like NE5532 .
See THIS PAGE for some popular "Today" IC Chips
terryking228:
I used 741's with +12V and biased to 1/2 (6v) for audio amplifiers back in 1975. It works OK.
Ah, ok... didn't know you could get away with that.
To be honest, I've never used the '741.
Used to work for Nat.Semi so they always had something newer and shinier to promote.
Yours,
TonyWilk
P.S.
In my interview, my to-be-boss asked: how would you light a 12V 20W lamp from a logic output ?
Me: scribble... mosfet
Him: nope.
Me: huh ?
Him: That's wrong because National do not make MOSFETs
A couple of transistors later, I got the job and realised I wasn't to design stuff,
I was to Design-In National stuff 
P.P.S. Unless you wanted Mil.Spec, then you could have 741's for $50 a pop
Hi,
then you could have 741's for $50 a pop
Wow, I remember paying about $12 for a 741 / 748 when the Philbrick Researches discrete-transistor boxes were $55.
As you can see, it's first in my box labelled "Linear ICs"
Here are 3 different ones in there:
One is National Semiconductor, I think. And one has a 1973 date code.
The silk-screen labeling wasn't too good back then. Today that would be evidence of a counterfeit. The dust on my box tells me they are genuine.
There is no way to say that 741 will work none without knowing the supply and output needs
LM741, LM741A ±10 ±15 ±22
aarg:
Probably. What bias voltage are you referring to? Please provide a link to information about the sensor.
Breath Alcohol Sensor 1000 ppm
Ethanol Sensor
Breath Alcohol sensor designed for applications in:
Law Enforcement Breathalyzer
Evidential Breath Alcohol Testing
Portable Breath Alcohol Tester
Personal Breathalyzers
It offers many benefits to your design
Small Size with Low Profile
Long Life (10 years expected life)
Fast Response (15 seconds typical)
Long Term Stability (2000 ppm overload)
Low Power (0 mW @ 0 mV bias)
Individually Calibrated
ROHS Compliant
Measure Breath Alcohol up to 1000 ppm
MarkT:
What is the supply voltage?What is the sensor?
Why would you choose a 50 year old opamp?
If you describe what you are trying to do, we will be able to help you choose the best approach,
its not clear that this circuit is useful to you without knowing all the details of your hardware
and what you want to do with it.
we are using the arduino uno board
we added a Bluetooth to our project
our project is about to make a wearable alcohol sensor to measure the alcohol level in your body.
here is the info of the sensor :
Breath Alcohol Sensor 1000 ppm
Ethanol Sensor
Breath Alcohol sensor designed for applications in:
Law Enforcement Breathalyzer
Evidential Breath Alcohol Testing
Portable Breath Alcohol Tester
Personal Breathalyzers
It offers many benefits to your design
Small Size with Low Profile
Long Life (10 years expected life)
Fast Response (15 seconds typical)
Long Term Stability (2000 ppm overload)
Low Power (0 mW @ 0 mV bias)
Individually Calibrated
ROHS Compliant
Measure Breath Alcohol up to 1000 ppm
Guess this would be too hard https://www.spec-sensors.com/product/breath-alcohol-sensor-1000-ppm-pinned-package/
we are doing a project about wearable alcohol sensor to measure alcohol level in your blood.
we will build the following circuits on Arduino Uno breadboard.
we will install alcohol sensor to measure alcohol level and Bluetooth for sending data.
anyways my question is that :
I am going to buy a rechargeable battery for the project but I need to know how many battery volts we need ?
here is info about the sensor and the Bluetooth :
Also here is the websites for the sensor and the Bluetooth :
Rather than me looking at all the links you have, why don't you just list the voltage requirements for each of the devices and post that then we can all look at what you have. The volts, then should be obvious.
Paul
Wawa:
Continuation of this project:
I guess he still is looking for someone to do the project for him.
Paul
Threads merged.
The links have more information than the OP can provide.
Here is the most important one:
I posted there pdf on this they really don't give much about what you need they sale a board to use this with
for a little over $50 I'm sure they want you to buy it.
bias Ethanol 1000 ppm +100 mV that's about as much as it shows
