I have been working on a project that uses an Arduino to control the locking/unlocking of Jack and Jill bathroom doors. As part of this project I am using a DFplayer audio board to issue verbal warnings as to the door status - "Close Back Door", "Bathroom is Locked" etc. My goal is to issue these warnings over the speaker in the bathroom that is part of my whole house audio system. I tried this circuit: http://www.geofex.com/article_folders/cd4053/cd4053.htm. While it works fine, it requires a separate power supply and I would like to make one that works off of only a 5V trigger from the Arduino. Based on extensive internet searching I settled on a DPDT relay based system using a single TQ2-5V Relay. When I breadboarded this it worked perfectly, but when I went to production with a fab'ed board I got a loud pop when the relay switched from Music to Message. It does not pop when it switches from Message back to Music. I can't explain why the bread board worked but the production board did not? I suspect the pop only occurs on the music switch because it is always on (no way to mute it during switching) while the message is muted (via software) before/after each switch. Note, the inputs are stereo line level from either the DFplayer or the Whole home audio source and the output is to the whole home amp which has 40 watts/channel at 8 ohms. More internet research (many hours) led me to an RC based circuit. The attached is my current Eagle schematic. Finally, I am only switching the positive legs (seems like religion on whether or not negative legs have to be switched) because the DFplayer has its audio ground tied to system ground - thus there is no way to isolate the audio grounds from the system grounds.
After this (sorry so long) introduction I have the following questions:
1) Is this the right approach to eliminate pop?, if not please recommend another.
2) What are the correct values for the resistors and capacitors and why? I currently have breadboarded the same as recommended in the CD4053 design, but values recommended in my internet searches range from 2.2uF to 470uF and 100 ohms to 1M ohms. Please note the CD4053 design has the resstors going to a reference voltage while the relay design has them going to ground.
3) What is the correct orientation of the capacitors - in the CD4053 design they all have positive connected to the CD4053, but it seems logical to me that the input capacitors would be biased opposite the output capacitors?
Thanks in advance,
Tom
After this (sorry so long) introduction I have the following questions:
1) Is this the right approach to eliminate pop?, if not please recommend another.
2) What are the correct values for the resistors and capacitors and why? I currently have breadboarded the same as recommended in the CD4053 design, but values recommended in my internet searches range from 2.2uF to 470uF and 100 ohms to 1M ohms. Please note the CD4053 design has the resstors going to a reference voltage while the relay design has them going to ground.
3) What is the correct orientation of the capacitors - in the CD4053 design they all have positive connected to the CD4053, but it seems logical to me that the input capacitors would be biased opposite the output capacitors?
Thanks in advance,
Tom
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