FAN - Problem GND??

Hello guys

I did the following circuit:

Can someone tell me if I'm calling the masses in the right place?

I'm connecting to digital GND pins to ground source 12V.
Side analog pins'm calling the mass of the power supply of 16.4 V to GND Analog!

Basically the fan immediately starts to work, when I have the 11 pin level "LOW". : |

Greetings.

http://forum.arduino.cc/index.php/topic,148850.msg1118325.html#post_etiquette

Ha Pedro,
Please remove one of the double posts, and we can start working on the one that is left.
Thanks

jackwp:
Ha Pedro,
Please remove one of the double posts, and we can start working on the one that is left.
Thanks

Done :slight_smile:

What I understand is:
when the signal from arduino, goes low (ground), the transistor should not conduct, so the fan should be off. But, unexpectedly, the fan runs.

  1. Disconnect the wire from the arduino (d11). Does the fan run now?
  2. Touch that wire to ground (the one you took off d11, and is now still hooked to the 2 resistors). Does the fan run?
  3. Touch that wire to +5v. Does the fan run?

I assume that led near the transistor is working as you expect it to?

This is the real problem ..

The potential difference of the masses is 8.2 V.

I see a solution that wanted to put the output of the circuit, ie ahead of V0, one OPAMP 741 and make the OFFSET adjustment, up the internal signal 8.2 V, so the masses remain with the same potential - Zero !

Any other suggestions or best way on how to make this adjustment?

You didn't do the three tests I suggested?

I do not understand your word "masses". What does that mean?

Are you saying (your schematic also indicates), you are attaching the output of OP1 to ground?

jackwp:
You didn't do the three tests I suggested?

I do not understand your word "masses". What does that mean?

Are you saying (your schematic also indicates), you are attaching the output of OP1 to ground?

The fan runs for about 10 seconds but then stops and the engine is making noise ..

I connected the pin 1k resistor directly to the mass and the same happens.

I plugged in the 5V Arduino power the fan and it works without stopping, even with the entry-level D11 Low and connected to ground

Sorry,
*masses is ground

If:

The fan runs for about 10 seconds but then stops and the engine is making noise ..

I connected the pin 1k resistor directly to the mass and the same happens.

Sounds like the transistor is bad. When the base is connected to ground through the 1k resistor, it should turn off. You sure that is an NPN transistor connected as shown? I assume if you disconnect the transistor from the motor, then the motor will stop, right?

and if i conect one fan of 5V, to 8,2 V??
and the ground to analalog ground??

I use volts regulators 7806 and 7906, to garante the 6V in my Vo output.. you think the fan in 8,2v will afect my Tension Output??

Firstly that circuit seems to have an opamp without a feedback network (after the sensor bridge). Or
is it a fixed gain instrumentation amp?

Secondly you are sending a signal in the +/-8V range to an Arduino analog input pin, thus destroying the
Arduino - you must restrict voltages to 0..5V range at all times.

Thirdly you have two independent supplies to the same Arduino - if only one is powered up
you may have issues - add a 10k resistor in series with any input that might otherwise try
to power the Arduino when its rails aren't up.

(Oh and you are using a '741 - once a mainstay of signal processing, these days it is more like an
embarassment :slight_smile:

First thing, I don’t think “analalog ground” is the same as the normal ground, so don’t use it.

Second, what is Vo output?

You said that a grounded base on the transistor, made the motor run?
Did you try pulling the transistor? Did the motor stop?

MarkT I'm using voltage regulators to reduce from 8.2 V to 6.0 V and the output of the circuit I have voltages between 0 and 5V connected to the analog input of the Arduino... The first Ampop is 741, which I am using to divide the input voltage into two symmetric voltages, in which I will need for the instrumentation amplifier .The second Ampop is INA128 - Amplifier Instrumentation.

You are right in saying that I have two different grounds and hence be having these problems in turn on the fan, because I'm having a potential difference of 8.2V between the grounds of the fan (Power Supply) and the output of the circuit (symmetric voltages).

I think I have two solutions here:

  1. Put one Ampop in output voltage Vo, and make an adjustment OFFSET grounds to get to the same potential difference;

  2. Put a fan of only 5 V to 8.2 V connected symmetrical source and connected to the same common ground ..!
    [Here I put the question when the fan start working will affect the the output voltage, Vo, or as I am using voltage regulator ensures that it will not affect ..?
    And if aa fan is 5V, and the power supply is 0.35A, which is the current ideal fan to once again do not affect the output voltage, Vo?]

[In the Wheatstone bridge I have a temperature sensor that varies the output voltage according to ambient temperature.
In Arduino I am defining that output voltage, Vo, is greater than 4 volts, turns the fan on .. but if the fan is on, can the output voltage Vo to be affected?] - With this second solution??

Suggestions?

A grounded base on the transistor, made the motor run?
Did you try pulling the transistor? Did the motor stop?

If you have a problem with the transistor, it does not matter what you do before that.
First thing to do is to get the transistor/fan motor checked out.

In theory, if you apply a ground to the base of that resistor, the fan should stop,
If you apply a positive voltage, it should run. So far you tell us that is not the case, and then start asking about opamps and arduino. Forget those until you get the transistor/fan to work right.

What do you think?

I do this conection..

The Van stop 10 seconds after i connect and stay stopped ever.

The GND from Power Suplly 16,5 V is conect to GND of Fan, and to GND from Arduino...

Hi Pedro,

Take the arduino out of the circuit. Just check the transistor and fan.

In theory, if you apply a ground to the base of that resistor, the fan should stop,
If you apply a positive voltage, it should run. So far you tell us that is not the case, and then start asking about opamps and arduino. Forget those until you get the transistor/fan to work right.

What does this do?

I will tell something tomorrow, because now i’m not in the school… :frowning:

Thanks :wink:

Hang in there Pedro. It's a learning experience. I don't know all the answers (heck, I don't even know all the questions), but, I bet we get it figured out together.

Hi.

This is my circuit:

The fan don't work, anyone can tell why? The fan have a white wire, but for what i read it's not necessary to conect.

If i put the black wire fan, to the ground, the fan works.. :~

This is my transistor:

I think the conections is fine..
Base, from 5 V Arduino, pin 1,
Conetor from black wire fan, pin 2,
Ground, pin 3.

Tell me something!!

Hi Pedro,

Take the arduino out of the circuit. Just check the transistor and fan.

Quote
In theory, if you apply a ground to the base of that resistor, the fan should stop,
If you apply a positive voltage, it should run.

Tell us what happens.