You can't just get an adapter, you also need something to bring the signal up to the minimum for VGA - 640x400 [31.5kHz] - since most VGA displays wont sync at frequencies low enough for the A500.
You'll need a line doubler or upscaler device and you'll probably want to spend a lot of time researching it (google, youtube) because some of these things are quite pricey.
Line doublers will generally give you VGA, and upscalers will provide 720P or 1080P HDMI outputs.
There is a DB23 to SCART adapter on trademe at the moment though, that'd work with a SCART to HDMI converter if that suits.
I personally haven't tried any as I just use my 1084S CRT, but the topic comes up a fair bit.
Just my two cents, hopefully some Amiga regulars pop by and share their experiences.
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