I teach highschool physics, and want to connect my smartphone (LG V20) to a Chladni plate (vibrating plate for studying interference patterns in sound in solids).
I have successfully done this by connecting a standard 3.5mm male-to-male lead to the phone, and crocodile clips on the other end, connected by 4mm leads to a vibration generator with the Chladni plate attached. This works, and I can play tones and even music through the Chladni plate, and see interference patterns start to form.
However the amplitude is far below what I need. I have a signal generator with amplifier which works well, and provides a peak output of around 6V; the speaker cable sending the same signal provides around 0.4V.
I therefore need a signal amplifier, ideally that inputs and outputs on 3.5mm or 4mm, and outputs with a variable setting up to around 20x. I know almost nothing about electronics, and the school doesn't have a tech lab, but I do have an old Marshall G10 Mk2 (10W guitar amplifier) . I would like some advice on how to cannibalize this speaker/amp to achieve my aims.
I did already connect these, attaining an appropriate voltage, but the quality was very poor - a lot of hissing and apparently poor connections. I'm unsure if this is to be expected, or a sign of a problem with the amplifier. The speaker in the Marshall is broken, but may be fixable.