circuit-designconnectorpinsschematicsspeakers
I have a circuit schematic (this is just a part of it):
I am trying to find what those little circles above and below the speaker are. I dont think they are part of the speaker itself, as there is more of them elsewhere in the circuit without any speakers attached.
My best guess would be they are some kind of connection pins, but i couldnt find anything.
A similar schematic I found is this one
Obviously is not this because the DSP chip has only 20 pins and the jack optput is placed in a different position
The amplifier chip is something similar to MC434119 , datasheet and looking into it I see the possible reason why you failed. The pot is in the feedback path not on the input path, leave the pot in place otherwise the gain is way to high and the circuit is unstable or oscillating. Jason's solution might work but it needs a decoupling capacitor to break the DC path through the external source.
The synth output goes through C4 (marked in red) to the jack output path (in purple) and to the amplifier path ( in yellow ).
What you can do is to unsolder C4 or cut the trace to it and use the Jack connector as input.
If the volume is to low then short the 10K resistor in the path (the one with 103 on it under the purple arrow).
To minimize the noise and spare battery power you can also cut the power to the synth chip by unsoldering the small 3 pin chip on the right of the yellow arrow or at least it's upper left pin. Just for the record, I don't understand why it has a permanent 4.7 ohm load that drains the battery with no obvious reason.
Best Answer
Probably tie points, terminals, headers/pins, loose wires, etc.
The diagonal line probably imitates something like a cross-screw, or clip, as you would have in a screw terminal, terminal strip, Fahnestock clip, etc. The diagram seems old, and these traditions probably date back to the 40s or thereabouts; they may also be relatively current, check ANSI schematic standards for ideas.
The purpose of indicating them on the schematic, might be for assemblers or repairpersons looking for where (or when) to attach the speaker leads (whether by connectors or soldered), or to populate BOM items (more in the post-CAD era, where automatic BOM generation is available; the symbols ought to have designators, then, too).
If you don't have a library symbol to use, drawing it anew is probably the intended route (perhaps making your own library as well).