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Simulating Disk Sounds

If you’ve ever used an Apple II computer, then you’ll remember the click-clack-whack sounds of a 5 1/4 inch floppy drive. The internal stepper motor moves between tracks on the disk, and every step makes an audible sound. When the computer first boots, it makes an unforgettable buzzing sound as the stepper is repeatedly whacked into the mechanical stop at track 0. By comparison, running an Apple II with a Floppy Emu disk emulator is silent. Should we add back some of that old-fashioned noise?

I built a simple circuit with a 12V relay that’s controlled by the Phase 0 signal on the disk interface. Phase 0 is one of the four control signals for the disk stepper motor, and ignoring the other three signals won’t produce totally authentic sounds, but it’s pretty close. The circuit uses a transistor, so the coil current won’t be drawn directly from Phase 0. The relay here isn’t actually controlling any load – the coil is energized simply to create a mechanical click sound. And it works! Here’s the demo:

Relays can be awkward to work with, they require a comparatively large amount of current compared to digital circuits, and a diode to prevent dangerous voltage spikes when the coil shuts off. What about using a speaker element instead? I modified my circuit to replace the relay with a tiny speaker that I had in a drawer, and change the driving voltage from 12V to 5V. To be honest I have no idea what the speaker’s specs are or how much current this might be drawing from the supply, but it works:

I was considering integrating a click relay or speaker into the much-discussed Floppy Emu daisy chain adapter. What do you think? After running these tests, I’m less excited about the idea than I was initially. It’s fun for a few minutes, but after that I’m concerned it would grow irritating. I could include a disable switch, but it seems foolish to incur the expense and design time of adding this extra feature if most people will turn it off anyway. Relays and speakers aren’t exactly cheap either, at around $1.00 to $1.50 in the quantities I’m looking at, making them more expensive than a microcontroller. Rapid on-off switching of the coil or speaker current will also generate electrical noise in the power supply and disk I/O signals, increasing the chances of disk errors if the signal quality is already marginal. So even if cost isn’t an issue, malfunctions are still a risk.

Of the two versions, I think I prefer the relay’s more authentic sound, but the speaker would be easier to work with and probably less likely to cause electrical trouble. Either one could work. Aside from the difference in tone, the speaker also produces a different series of clicks than the relay. The speaker can respond more quickly to changes on Phase 0, while the relay’s mechanical design likely misses any Phase 0 pulse that’s shorter than a few milliseconds.

If most people feel this is a compelling extra feature, and they wouldn’t mind the few extra dollars in cost, that’s great. But if the reaction is more mixed or merely “would be nice”, then I’ll probably leave it out.

Read 17 comments and join the conversation 

17 Comments so far

  1. Keith Kershaw March 21st, 2019 1:38 pm

    Steve,
    Was not a fan of the original drive sounds, so this would not work for me. If I get nostalgic will put a couple of HD disks in the duodrive and wait for the io error. Lots of click’s there.

  2. Dillon Nichols March 21st, 2019 3:12 pm

    Super fun idea but I think that is a feature that belongs in the past. Another option may be to have the pads on the connector and leave the parts unpopulated and the savy can add the components themselves if they desire the sound.

  3. Michel Kakulphimp March 21st, 2019 4:03 pm

    I think this is a really fantastic idea. At the very least you should include a header to attach the speaker!

  4. Jerry March 21st, 2019 6:36 pm

    Just put in a header or a 1/8\” jack so someone can hook up their own speakers.

  5. Steve March 21st, 2019 9:17 pm

    I normally try to avoid optional features or unpopulated footprints unless there’s no downside. In this case, including a relay or piezo on the daisy chain adapter board would probably involve some tradeoffs that don’t make a lot of sense if it’s not a standard feature. It’s more than just including a header. I’ll give it some thought.

    This might make more sense as a stand-alone item. A pass-through board with a slightly improved version of the relay circuit would be easy to make.

  6. groinksan March 21st, 2019 11:37 pm

    DO IT!!!! One of the things I miss when using the Emu is the noise.

  7. dk3406 March 22nd, 2019 12:40 am

    Do you know what?

    On my IIGS, with 4Sonic Sound card built in, I’ve added an external sound mixer device to merge its speaker output and the sound card output into *one* external speaker, to manage their different volume controls.

    A device like this could be easily added to a setup like this.

  8. Peter March 22nd, 2019 6:22 am

    I vote for a pass-thru board which I most certainly would buy or make. I love the old sounds.

  9. Gary March 22nd, 2019 8:36 am

    I like the idea… On my II+, I’ve stuck with physical floppies in part because of sound they make.

    However, the stepper is just one component in the floppy drive sounds. There was often an initial clack! noise of the drive motor starting up followed by the steady swish-swish-swish of the disk as it spun. Only then would you get the tick-tick-tick of the stepper moving the head. And there’s the unmistakable sound of the drive head hitting its limit (which William Gibson charmingly called “a farting toaster” noise) which usually indicated something was wrong with the floppy.

    I also recall the UniDisk drive’s varying sound of the drive motor as they sped up and slowed down depending on the track they were reading.

    I sort of doubt the floppy emu emulates all parts of the floppy system (i.e. the turning on of the drive motor, or tracking where the head is) so a lot of that might not be available for emulation. But I’d consider buying a pass through that would emulate the sounds or even expose those signals to something that could emulate those sounds (i.e. like a Raspberry Pi you could load up with sound samples of actual disk drives).

  10. UpgradeFever March 23rd, 2019 8:47 pm

    I would love to have a sound option. So something that could be on/off.

  11. Rusty March 25th, 2019 3:50 pm

    Love the idea! I’d upgrade from my revB immediately. 🙂

  12. Ted Thompson March 27th, 2019 12:19 pm

    Great idea. I’d say do it, but have an option to disable, and maybe control the volume level of it.

    You got to know the drives sound, and it was a very real feedback that could alert you to a problem. Even if thinga like media failure are all but eliminated by not using actual floppies, it’s something I’d miss.

  13. Tim Buchheim March 27th, 2019 2:07 pm

    I’d skip it. When I want to listen to floppies I’ll use my actual floppy drive.

  14. Steve March 27th, 2019 3:09 pm

    Sound effects didn’t make the cut for the daisy chain board. When I have time, I’ll design a simple pass-through board with sound effects for those who like mechanical nostalgia.

  15. Jack March 30th, 2019 9:37 am

    The relay would be a better idea, it’s more acoustic and mechanical sounding.

  16. James Lewis March 31st, 2019 8:56 am

    The only sound I miss is the servo slamming into the rail at power up. The noise during operation would be a nice indicator something is going on, but not necessary. I’ve gotten to a point of disabling drive activity LEDs on my modern devices because the flickering is annoying (and unnecessary.)

    That said, knowing how to get back some sounds when I’m nostalgic for them is worthwhile. 🙂

  17. Case Harris April 11th, 2019 11:58 am

    I’m über-nostalgic over munch //e and IIgs, so I’m all for sound recreation!

    In my other hobby – R/C model aircraft – much has been done to produce full-scale internal combustion engine noises from a modern electric motor setup. I’m currently working on an oversized vape atomizer to produce “smoke” on an electric motor powered aircraft.

    For the Emu, would it be practical and/or functional to simply sample the various drives’ clicks, clunks, and whirring and store them on a chip for playback via the small speaker?

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