Hi
I have a project where I'm trying to drive audio from my own source (an **broken link removed** from Nuvoton) into the speaker of a kid's toy that already has its own sound driver. When I hook up the output of my source, I notice a significant drop in the level of the toy's output, to a level so low that it's barely detectable. This is, I'm guessing a conflict between impedances of the two outputs. I can see the toy's audio output consists of a chip coupled to an SMT transistor, and the ISD2100's seems to be direct from the IC itself.
In fiddling with the circuits, I connected two low value resistors (47 ohms), one on each source's output, then fed that into an **broken link removed** I had lying around. It partially worked, but the amp's input level control (the pot in the diagram) has to be adjusted just to the point where it wants to start squealing (feedback?) to work, a condition that also has a lot of distortion.
Can someone please explain the interactions I'm seeing between the two sources (why one swamps out the other, even when not outputting anything) and/or recommend some designs that would work well for this application to make the two sound sources share the same speaker without distortion? Should I be using dual amplifiers, each with their own gain adjustments? Maybe an impedance matching transformer on the toy's output?
Thanks in advance for your help!
-Dewey
I have a project where I'm trying to drive audio from my own source (an **broken link removed** from Nuvoton) into the speaker of a kid's toy that already has its own sound driver. When I hook up the output of my source, I notice a significant drop in the level of the toy's output, to a level so low that it's barely detectable. This is, I'm guessing a conflict between impedances of the two outputs. I can see the toy's audio output consists of a chip coupled to an SMT transistor, and the ISD2100's seems to be direct from the IC itself.
In fiddling with the circuits, I connected two low value resistors (47 ohms), one on each source's output, then fed that into an **broken link removed** I had lying around. It partially worked, but the amp's input level control (the pot in the diagram) has to be adjusted just to the point where it wants to start squealing (feedback?) to work, a condition that also has a lot of distortion.
Can someone please explain the interactions I'm seeing between the two sources (why one swamps out the other, even when not outputting anything) and/or recommend some designs that would work well for this application to make the two sound sources share the same speaker without distortion? Should I be using dual amplifiers, each with their own gain adjustments? Maybe an impedance matching transformer on the toy's output?
Thanks in advance for your help!
-Dewey