Thank you Drake, I will add a little explanation from my point of view...
Idea
The idea of making a noise board with a small relay has been around for a while. I chose a small microcontroller to solve this easily. I made this with ATTiny85, but I may change it to ATTiny13A due to availability issues. Now that these aren't available, I've created two programs to work with both.
The prototype was made with a universal board. It sounded pretty good, so I handed over the schematic to Stephen and he designed the PCB. Drake was in charge of drawing the cute artwork. I think this has become a pretty fun device.
Programs and sounds
The sound is divided into two stages.
The hard drive has an initial start-up sound. The initial start-up sound is inspired by Quantum's old drive. It is a familiar sound that the clutch disengages and the splatter starts to move due to centrifugation. It waits 3 seconds when the power is turned on and then makes a sound. This always activates the relay when the power is turned on, regardless of the actual access to the SD card, but it is only once and will not start after that.
Next, you will hear a sound linked to the access of the SD card. This repeats ON and OFF of the relay 10 times per second. Of course, this doesn't make any sound when there is no access.
About the sound of the relay
The Beleth ’s Drum PCB is fixed with 1mm double-sided tape or 2mm screws. The layout is up to the user. If you replace the double-sided tape with a sponge, the sound will be less reverberant and muddy, and if you attach it directly with screws, the reverberant sound will be loud and a little noisy. Also, if you wrap a sponge and mute it, the volume will drop to the point where you can hear it faintly, so it should sound more realistic.
Devices that can be connected
It is designed on the assumption that it will be connected to BlueSCSI, but since the voltage of a device with an LED output of about 2V can be input, it can also be connected to the device you can imagine. Of course, it can also be used for CF card adapters and SSDs.
*This is the prototype#1
About connection
From BlueSCSI, take out + and- (anode and cathode output) from the ACT output pin and connect them.
Unfortunately, it cannot operate at the voltage that the LED shines, so it is necessary to supply 5V power from Berg cable for Floppy.
The LED lights up by relay operation. It can be removed. If you prepare a wire that can be extended to the front panel of your Mac, you can also illuminate the LED on the front panel...
Finally, a Japanese named "okkun" helped me to make the program. I am deeply grateful to him.
And this time I made the overall specifications and schematics, but Stephen and Drake of the Satanic Mac Club are also good at this kind of work than me, so the products they will lead will be released in the future. We love small devices so we don't make big ones, but we want to make a lot of devices to enjoy your Mac...
We value our relationships with each other rather than our claims. For that reason, I want to be honest above all else. There may be times when we use someone's ideas, but they should all be manufactured with permission. And I'm the oldest, and I'm sometimes worried that this motivation will continue 10 years from now, but I hope the younger ones will pull me. I am also deeply grateful to Stephen and Drake.
Thank you for reading to the end.
Beleths Drum 
