Go Down

Topic: Need Help Verifying the Circuit (Read 506 times) previous topic - next topic

Anirudh_Ram

May 15, 2019, 02:38 am Last Edit: May 15, 2019, 04:57 am by Anirudh_Ram
I have a circuit here that I plan to make a PCB with. The Arduino is supposed to power ON and stay on with the press of Push button 1 (Digital Pin 6 will be updated to high on Press). To Turn off the Arduino you must press push Button 1, while pressing and holding down push button 2 (Delay will be accounted to update D6 to LOW once both buttons have been pushed and released).

The Circuit also contains a 7.2V (Coin-Cell) backup battery along with a primary DC source of 9V coming from the wall outlet (Use of an Adapter Plug).

I am only a beginner to Electronics so please let me know if I am doing things the right way. Also, verify that I have my resistor values right. The Base-Emitter Voltage on the NPN Transistor (2SC945) is 5V. Infact want to make sure all wires leading to the Arduino is 5V to prevent frying the board.


Please suggest any edits I should make in the circuit.

Thanks in Advance,
Anirudh

Anirudh_Ram

Sorry everyone. I must have hit "post" too quickly. Here is the picture of the circuit Diagram.

septillion

Will not work, you will blow the base if D5 is powered. Also, buttons without pull resistor will not work.

But why use an external circuit at all? Just put the Arduino to sleep, it will use very very very very little current.
Use fricking code tags!!!!
I want x => I would like x, I need help => I would like help, Need fast => Go and pay someone to do the job...

NEW Library to make fading leds a piece of cake
https://github.com/septillion-git/FadeLed

Anirudh_Ram

How would I put the Arduino to Sleep? Is there a circuit for that?

septillion

See https://www.gammon.com.au/forum/?id=11497

All baked in to the chip itself :)
Use fricking code tags!!!!
I want x => I would like x, I need help => I would like help, Need fast => Go and pay someone to do the job...

NEW Library to make fading leds a piece of cake
https://github.com/septillion-git/FadeLed

srnet

#5
May 15, 2019, 12:50 pm Last Edit: May 15, 2019, 12:50 pm by srnet
How would I put the Arduino to Sleep? Is there a circuit for that?
The way that circuit is drawn makes it very difficult, for someone who does not know your circuit to read. Gave me a brain hurt.

An Arduino Uno will consume several mA if you just put it to sleep.

Using a logic pin, once the Arduino is started, to keep the high side switch transistor on (by providing it with base current) does need a resistor in series to the base to limit current.

However the circuit will not work, when you attempt to turn off the high side switch the logic pin will be pulled to ground and this keeps the transistor switch on.

You need an extra NPN transistor in there, which you turn on with a logic high signal from the Arduino and the collector of the NPN pulls the base of the high side switch low. Then when the logic pin is pulled to ground, the NPN is off, there is no base current to the high side switch and it stays off.  

http://www.50dollarsat.info/
http://www.loratracker.uk/

septillion

Uno, yeah without modifications, yeah. So I would go for a Pro Mini and remove the power LED. Makes it possible to go down to 360 µA.
Use fricking code tags!!!!
I want x => I would like x, I need help => I would like help, Need fast => Go and pay someone to do the job...

NEW Library to make fading leds a piece of cake
https://github.com/septillion-git/FadeLed

Anirudh_Ram

I tried changing up my circuit a bit. Does this look right?

srnet

I tried changing up my circuit a bit. Does this look right?
Cannot tell.

The 'schematic' is too difficult to read.
http://www.50dollarsat.info/
http://www.loratracker.uk/

Anirudh_Ram

This should be much more clearer.

MorganS

This should be much more clearer.
Not really. The upside-down text is the worst part.

Second-worst is the lack of names on the parts. Names like R4 and Q2 are really important so that we can discuss the circuit, instead of "the second diode on the right."

Then there's more cleanup that could be done, such as using ground symbols but that isn't interfering with understanding the diagram at this point.

So,looking at the circuit, you have two 3V batteries in parallel, feeding through a series of diodes to the Uno's barrell jack, which itself has a series diode. Each diode drops 0.7V, so how could this possibly power an Uno which requires 5V?
"The problem is in the code you didn't post."

Anirudh_Ram

The batteries are actually 3.7V, and how do you know that the diode each removes .7V?

dougp

how do you know that the diode each removes .7V?
The perfect diode does not exist, they all have some forward voltage drop.
Everything we call real is made of things that cannot be regarded as real.  If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet. - Niels Bohr

No private consultations undertaken!

MorganS

The batteries are actually 3.7V,
Please update the diagram.


Quote
and how do you know that the diode each removes .7V?
Because I read the datasheet.
"The problem is in the code you didn't post."

Anirudh_Ram

I have uploaded a new version of the schematic, having fixed the errors people have complained about.

Go Up