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Miniscribe 8425S Sound Reproduction

jmacz

Well-known member
My Quadra 700 is running off of a ZuluSCSI 1.1 and that works great but I definitely miss the noises from a physical hard drive. Specifically, I miss the crazy noises from the Miniscribe 8425S 20MB hard disk I had in my Macintosh SE back in the day.

I first thought of developing an extension which reproduces the sound but that would only kick in after the Mac boots. I decided to try something else first.

I was able to get my hands on a working Miniscribe hard disk and used a Tascam DR-40 to record the noises. I then cut it up into shorter samples and copied them into an Adafruit Audio FX Mini Sound Board. It can take 10 samples and play them back randomly using a pin as a trigger. The idea was to tie this pin to the LED activity light from the ZuluSCSI as a trigger.

I recorded a video of the first test below. The speaker I got (an Adafruit 3885 Stemma Speaker) is kinda weak and I'll have to find another option. Very much a hack but thought I'd give it a try. :cool:

 

jmacz

Well-known member
The 10 samples are using up a little under 2MB, roughly 200K each. The audio fx module I had was the smaller one (they sell them in 2MB and 16MB capacities). The samples are mono 44KHz 16bit PCM wav files. The clips sound better on my Mac vs through this contraption so I'm in the process of determining whether it's the audio fx or the cheap mini speaker I'm using (guessing it's the latter). But if I'm able to get this semi working, I'll need to capture cleaner samples. Also I thought the stepper motor actuations were a higher pitch back in the day so need to look at whether or not this particular Miniscribe I procured is a good source for the samples or not. It's quite possible I need to take these samples with the drive mounted within an SE to capture the proper muffling from the case, rumble/echo via case vibrations, etc. There's no programmable controller on this audio fx so if I want to do more, I'll have to add a controller like a small Arduino in front of this managing the signals to the pins.

But anyhow, just a fun side project purely for the nostalgia :)
 

avadondragon

Well-known member
I've been thinking about doing this but actually driving the actuator arm of a Miniscribe (or similar) for the sound. I thought it would be cool to put in a MacEffects case and leave the top off the drive to watch it move. 😁
 

jmacz

Well-known member
I've been thinking about doing this but actually driving the actuator arm of a Miniscribe (or similar) for the sound. I thought it would be cool to put in a MacEffects case and leave the top off the drive to watch it move. 😁

Haha nice! That would be cool!
 

jmacz

Well-known member
@avadondragon @jmacz Someone did it with a TashTwenty, but I can't find the thread. It connects to a real Miniscribe servo and makes the servo whizz around during activity.

Ok, will explore that if this turns out to be sad. This is like $17 in parts ($14 for the fx board and $3 for the speaker) I had lying around from a halloween costume so was worth an attempt.
 

olePigeon

Well-known member
@jmacz Oh, no, no. I didn't mean your attempt has already been done. What I meant is that someone successfully controlled a servo motor on the TashTwenty. I figured it'd be worth looking into for ideas on how to implement it on a SCSI adapter since it's an entirely different device compared the TashTwenty.

This is fantastic work. Having the real sound synced up to the ZuluSCSI is freaking awesome. :D Plus you could change the sounds around too, I would assume. So if you like more bass you could have the thump of an old Quantum.
 

olePigeon

Well-known member
@mg.man Yes, that thread. And also, yes, apparently it was a Rodime. My memory isn't very good. But I wonder if it could be adapted.
 

warmech

Well-known member
@mg.man Yes, that thread. And also, yes, apparently it was a Rodime. My memory isn't very good. But I wonder if it could be adapted.
You bet. I'm wrapping up work for the day, but I'll post some schematics this evening. Long story short, it's stupid simple. The Arduino stepper motor library will drive it through an H-bridge without issue; the only thing you need to know is how many steps per revolution your motor has. The motor chassis probably has a model number on it somewhere; start with googling that and see if you can find a datasheet for the motor. If you do, it should tell you how many steps are in one rev; with that info, it's just plugging in some values in your code and running some trial and error testing and you're good. The stepper sequence you'll likely have to match by ear, though, to get the "pitch" (speed) right.

Edit: Just to be clear, taking this approach will render the drive useless as it disconnects the stepper from the hard disk and connects it to the Arduino via the H-bridge. This is really only to be used when your disk is unrecoverable (as my Rodime was) but the stepper is still functional.
 

jmacz

Well-known member
Well, it's been a little while. I started using a larger speaker and that definitely helps. I have it wired up and powered via 5V from the motherboard and it's using the LED signal to trigger. Learned something new... I didn't realize most hard drive LEDs (including the ZuluSCSI) are switched using the ground (ie. the positive is always hot and it's the ground connection that is on/off to drive the light).

Anyhow, I've run into an issue. The Adafruit audio board I'm using triggers based on a pin being held low for at least 125ms. The LED is actually flashing much faster... so it's not low long enough to trigger. If for example I remove the SD card from the ZuluSCSI, then it will blink slowly (to indicate no SD card) and that triggers just fine. But the normal hard drive activity is flashing the LED too quickly and not holding the low signal long enough to trigger all the time. Fun. I'll have to brush up on how to hold this signal low for a bit longer ... or I can introduce an Arduino to better control this. Will get back to trying some things when I get more free time. But as @dramirez stated earlier, after hearing these miniscribe noises non stop for a few hours messing with this today, silence might be better LOL!

Latest picture:

IMG_2128.jpg
 

Phipli

Well-known member
There is a 555 timer circuit called a "one shot" that would fix your 125ms issue. But to be honest, I'd use an ATTiny45, because it is far more flexible for the same size chip. You can program ATTiny45s like they were an Arduino, so you can include some programming logic.
 

jmacz

Well-known member
There is a 555 timer circuit called a "one shot" that would fix your 125ms issue. But to be honest, I'd use an ATTiny45, because it is far more flexible for the same size chip. You can program ATTiny45s like they were an Arduino, so you can include some programming logic.

Hmm, interesting. I'll take a look. Thanks!
 

Phipli

Well-known member
Hmm, interesting. I'll take a look. Thanks!
The ATTiny45 is actually quite good at doing audio using PCM. Better than an arduino Uno in fact. You could move your design to that and drop the Adafruit board. Use something like a single MOSFET to drive the speaker. It would be more compact.
 
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