It's in the transformer on a PCB at the bottom. I used a battery powered neon light bar from Amazon. Here is an example. https://www.amazon.com/lychee-Strobing-Electroluminescent-Halloween-Decoration/dp/B013FZHD06/ref=sr_1_39?dchild=1&keywords=battery+led+wire+light+3vt&qid=1613078040&sr=8-39

I can not find the original. But they all make the same noise. :-(