Hi folks, I have a really complex (to me anyway) analog project that I'm building for a Halloween prop. It's a 12 volt PIR sensor that triggers a TIP 31c that in turn grounds a 12 volt motor, 12 volt LED and a 7805 based voltage regulator that runs a 5v MP3 player and 5Volt speakers. *whew* Anyway, the TIP31c acts as a switch (tripped by the PIR signal) to turn everything on (and off) all at once. Here's my problem: the 5V power to the speakers requires a ground and because the speaker jack also has a ground there is an issue; if I run the speakers off the same 5v system running the MP3 it quits and if I run an external 5v to the speakers it negates the TIP31c ground switch and the system reads a constant 5v. I tried putting a diode between the external 5v ground and that didn't work... What am I doing wrong?

 

Schematic please........

 

Hi Rasmussons, thanks for replying! I was afraid you might ask that...the closest thing I have is a Fritzing diagram (I'm new to this stuff) but what is represented as a 9v battery is actually a 12v power supply, and the speaker is also plugged into a 5v PS which is what's causing the issue.

 

Do you have component part numbers so we can pull datasheets? And what exactly do you want this thing to do? Step by step?

 

Just as a side comment: Fritzing diagrams are difficult to read. I won’t try to read them. Schematics are the language of electronics and you’ll get more help on here if you learn how to draw one.

Drawing a schematic may show you the problem.

ExpressSCH is a free program that lets you draw a schematic with stage/drop/click actions. There are others.

 

Thank you all for your input! Sorry I never did get the time to draw a schematic, but it turns out that the amplifier on the speaker was blown and causing the ground crossover! New speaker and amp; problem solved! Thank you again for your input!