Hi All,
I’m new to the world of electronics and have run into a conundrum I cannot seem to solve on my own. I hope you guys can provide some context and insight into what is going on here. Looking to learn!
I have made 2 circuits, one with an lm386 to drive a speaker, and one circuit around a TL072 to pickup and amplify signal from a piezo disc. When powered individually each by its own 9V dc battery it works perfectly fine (top picture in attachment). However I want to combine both circuits to be powered by a single battery (bottom picture), which is when things go haywire. I am picking up the sound from the piezo, which is good, however a significant amount of (low quality) sound from the line-in is now also making it’s way into the output. Through the process of elimination I have narrowed the search down to the Voltage in. If the circuits are combined I get the noise, if on separate batteries it’s fine. I played around with different grounding arrangements, but this does not affect the performance. Similarly I’ve tried an array of decoupling capacitors, as well as a voltage regulator, but neither has an affect.
Does anyone in the community here have an idea of what might be causing such interference? Especially if the only culprit seems to be the Vin.
I’m new to the world of electronics and have run into a conundrum I cannot seem to solve on my own. I hope you guys can provide some context and insight into what is going on here. Looking to learn!
I have made 2 circuits, one with an lm386 to drive a speaker, and one circuit around a TL072 to pickup and amplify signal from a piezo disc. When powered individually each by its own 9V dc battery it works perfectly fine (top picture in attachment). However I want to combine both circuits to be powered by a single battery (bottom picture), which is when things go haywire. I am picking up the sound from the piezo, which is good, however a significant amount of (low quality) sound from the line-in is now also making it’s way into the output. Through the process of elimination I have narrowed the search down to the Voltage in. If the circuits are combined I get the noise, if on separate batteries it’s fine. I played around with different grounding arrangements, but this does not affect the performance. Similarly I’ve tried an array of decoupling capacitors, as well as a voltage regulator, but neither has an affect.
Does anyone in the community here have an idea of what might be causing such interference? Especially if the only culprit seems to be the Vin.
Attachments
It sounds like coupling via the impedance of the battery.
Which voltage do you call Vin?
Where did you connect the voltage regulator to and what type did you use?
Is the line output clean when you disconnect the loudspeaker?
Which voltage do you call Vin?
Where did you connect the voltage regulator to and what type did you use?
Is the line output clean when you disconnect the loudspeaker?
