The HDD Synth recreates the aural experience of old mechanical hard drive by playing back a recording of the start-up sequence, followed by the idling and access sounds.

I was inspired to create this after learning about the HDD Clicker which is an inspired and nicely engineered device, but one I felt I could exceed in realism.

After a purchase of a £5 Raspberry Pi Pico and £15 Pico Audio I found some mechanical HDD records and crafted some MicroPython code to play back the sounds at the correct times.

The next steps were to determine the best way to power and mount the device inside a retro PC.

At first the obvious way of powering it was by using a 5V rail from molex drive connector. However I then had the realisation that I could kill two birds with one stone by mount it all on an ISA card and using the 5V rail it exposed.

After some experimentation detecting HDD activity via the motherboard LED header, I decided instead to use an HDD activity LED output from a CompactFlash IDE adapter board.

The benefit here being that I didn’t need to capture the motherboard LED HDD activity and then rebroadcast it via a separate connection to ensure the case LED still lit up.

Although my original non-ISA mounted Pi Pico prototype was able to successfully detect the HDD activity via the motherboard LED using the analog inputs of the Pi Pico to monitor voltage. For some reason in the ISA mounted version this isn’t working correctly.

I’m certainly no electronics expert, but I suspect that the interference may be causing the voltage monitoring values to float above the trigger threshold even when the LED isn’t on.

My next steps are to setup another Pi Pico using an LED output to display the detected voltage from the HDD activity LED. This should help be debug what the problem is.

Once it’s all working I’m keen to open source the Python code and the hardware list so other than build on this work. I’ve considered building a few devices and selling them, but I’m unsure if they’ll be the demand and if it’ll be worth the effort.

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