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### Topic: Help reading voltage on an analogread pin (Read 7383 times)previous topic - next topic

#### mem

#30
##### Mar 01, 2009, 10:31 pm
I am not clear what you are saying.  Could you clarify what voltages you see when the pin connected to the base through the 1k resistor goes high?

On the collector (should be a fraction of a volt)
On the 12 volt line (should be 12 vols)
On both sides of the relay coil (this should be the same as the two values above)

#### StealthRT

#31
##### Mar 01, 2009, 10:39 pm
Ok..

goes high on the 1k = 0.76v on the base
on the collector = 0.03v
12v line = 12.07v
Yes, both are the same as the above values (0.03v & 12.07v)

Quote

On the 12 volt line (should be 12 vols)

You do mean the other side of the coil, right? The opposite end of where i am getting 0.03v?

David

#### StealthRT

#32
##### Mar 01, 2009, 10:45 pm
Here, maybe this will help?

David

#### retrolefty

#33
##### Mar 01, 2009, 10:55 pm
One question: Is the ground connection on the Arduino wired to the ground connection of the emitter lead of the transistor AND the gound side of the +12vdc power supply? They all have to be wired together for this to work correctly.

Lefty

#### StealthRT

#34
##### Mar 01, 2009, 11:10 pmLast Edit: Mar 01, 2009, 11:13 pm by StealthRT Reason: 1
I am using a RBBB kit

I have the grounds all connected to pin "G" between the 5v and A5 pins.

David

#### StealthRT

#35
##### Mar 02, 2009, 11:04 pm
Ok, i re-soldered the 10k to the base and it seems to work when i provide 5v on the pin BUT it doesn't trigger back off once i take away the 5v?

Base without 5v: 8.48v
Base with 5v: 5.87v

David

#### retrolefty

#36
##### Mar 02, 2009, 11:24 pm
Quote
Ok, i re-soldered the 10k to the base and it seems to work when i provide 5v on the pin BUT it doesn't trigger back off once i take away the 5v?

Well the Arduino output pin will be driving the resistor to either +5vdc or ground, not letting it just float. Does the relay turn on and off if you hook first to +5 and later then to ground to the resistor?

Lefty

#### StealthRT

#37
##### Mar 02, 2009, 11:31 pm
The relay turns on when i supply the 5v from the Digital Pin on the Arduino. Once i take the 5v away, the relay still stays on.. does not go off.

David

#### retrolefty

#38
##### Mar 02, 2009, 11:39 pm
Quote
The relay turns on when i supply the 5v from the Digital Pin on the Arduino. Once i take the 5v away, the relay still stays on.. does not go off.

I understand that, but if you then touch the disconnected resistor end to ground does the relay then turn off???

Lefty

#### StealthRT

#39
##### Mar 02, 2009, 11:40 pm
hum i have the resistor soldered to the ground and the base pin....??

David

#### retrolefty

#40
##### Mar 02, 2009, 11:42 pm
Quote
hum i have the resistor soldered to the ground and the base pin....??

That's not what you drew up. You showed the resistor connected to pin on the Arduino and the other end to the base of the transistor?

Lefty

#### StealthRT

#41
##### Mar 02, 2009, 11:47 pm
Yes i do not have the resister in the drawing. Do u want me to take the current resisiter on the pin OFF? so 5v goes to the base without the resister?

currently i have both the 1k resister AND the 10k resister....

David

#### retrolefty

#42
##### Mar 02, 2009, 11:49 pm
I'm sorry I'm having problems understanding, so it would be best to draw what you actually have and lets see what is what. Got to run out for now but will check back later.

Lefty

#### StealthRT

#43
##### Mar 03, 2009, 03:05 am
Ok here's another drawing of how its currently hook up

David

#### retrolefty

#44
##### Mar 03, 2009, 05:44 am
I see no reason for the resistor installed between the base and emitter of the transistor, not sure where in this thread it got suggested? Anyway the way it is wired should work even with the 10K resistor between base and emitter.
It's best to test your circuit independently of the Arduion by disconnecting the Arduino end of the 1K resistor. You should be able to test the circuit by applying +5vdc at the Arduino end of the 1K resistor and the relay should turn on. Then if you ground the Arduino end of the 1K resistor (while NOT attached to pin 9 of the Arduino) the relay should turn off.

If this doesn't work, either wiring error or component actual values wrong or component failure. It would be easy to troubleshoot if it was in front of me with my test equipment, but troubleshooting by posting back and forth is difficult at best. Is there anyone local that has electronics experience that might lend you a hand?

Lefty

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