Hi, i'm making a doorbell and i've tested it on my breadboard where it works perfectly fine. However, when i transfer it to a soldered circuit i have some issues. The switching of the transistor is ok, and works with my reciever/transmitter circuit. But the transistor does not draw current from the 9v battery attached at the collector. Instead it draws current from the Arduino board, just enough to turn on the amplifier circuit but not enough for any sound to play. I'm guessing it has something to do with my wiring or setup at the soldering board? There are should be no conductivity issues between the soldering tho.

Any tips or recommendations are highly appreciated. I have attached a quick schematic and a picture of my horrible soldering job.

 

Welcome to AAC!
Your board pic shows some unsoldered pins. Is that correct? IC input pins should not normally be left floating.
The solder for D2 strays on to the pad for one of those pins.

 

Thank you Alec!
That is correct that i didn't solder all of the IC pins. However my issue is not with the switching or signal from the reciever. My issue is with the amplifier module that is not getting enough current to play any audio through the speaker

 

UPDATE: I've included a picture of my wiring.

most orange: 5v from Arduino to reciever, orange: from arduino_11 to trans. base, purple: from reciever D2 to arduino_2, red: 9v+, green: 9v-, white: emitter to amp+, gray: arduino_gnd to amp-.

 

I don't see any series resistor to limit the transistor base current which the Arduino is providing. The base-emitter junction of the transistor plus the speaker resistance may draw enough current to have damaged the Arduino output stage or the transistor.
With the speaker driven the way you show (via an emitter-follower) it will never see more than about 5V-0.7V = 4.3V.

 

No worries, it works as intended and first laid out. There was a loose connection between the ground to the 9V battery or something. I ended up hooking the ground to the reciever and the 9v battery up just next to each other and now it works.

 

Resistors are cheap and can keep your Arduino from driving the transistor so hard that it might shorten the life of either the transistor or more expensively, the Arduino.

 

So you suggest adding a resistor to limit current at the base of transistor?

The arduino can only supply 20 mA at max from digital pins and as far as i can see from the datasheet for the transistor base could handle 20 mA. The amplifier has a max current rating of 500 mA and is only drawing 300-400 at max, so would i need another resistor in series here to limit current here? And the arduino can handle 9-12v and iv'e read somewhere it can handle an input of 1.25A to 2A. Thank you for the advice, i'm just usnure how to apply it

 

The arduino can only supply 20 mA at max from digital pins

Sureley that is the specified maximum allowable current; not the near-short-circuit current?

 

Your circuit does not have an audio amplifier. Instead it has a transistor putting pulses of DC in the speaker.
A speaker is usually driven with AC, not DC.

 

So you suggest adding a resistor to limit current at the base of transistor?

The arduino can only supply 20 mA at max from digital pins and as far as i can see from the datasheet for the transistor base could handle 20 mA. The amplifier has a max current rating of 500 mA and is only drawing 300-400 at max, so would i need another resistor in series here to limit current here? And the arduino can handle 9-12v and iv'e read somewhere it can handle an input of 1.25A to 2A. Thank you for the advice, i'm just usnure how to apply it

Often experience is the best teacher.

 

Your circuit does not have an audio amplifier. Instead it has a transistor putting pulses of DC in the speaker.
A speaker is usually driven with AC, not DC.

I don't know how it works but i think the blue module on the picture is an amplifier?
At least the description is; "Compact MP3 audio module with integrated 2W amplifier, starts automatically when power is supplied." I'm only using the N2222A transistor as a switch where Arduino sends a "high" pulse for a specific duration to the base of the transistor so 9V can be supplied to the amplifier from collector to emitter.

 

so 9V can be supplied to the amplifier

No. With the configuration you show, only about 4.3V gets supplied to the amplifier.

 

In your post #1 you show an unlabeled "box". Is it an audio amplifier?
What is the function of its pins 2 and 11?
Who sells it? Who makes it? Doesn't it have a detailed datasheet?
What is the impedance of the speaker?

I think the amplifier output should feed the speaker, the transistor should feed the amplifier some DC power. The transistor should be two transistors making a DC level shifter that applies 9VDC to the amplifier when the receiver is activated.