The “Spindicator” Project

63 thoughts on “The “Spindicator” Project”

    1. Thanks for the comment. An interesting idea, I’m going to have to give that a go and see what it looks like.

    1. An interesting idea with the 555 timer. I was sure that others must have done this before, but I didn’t find you post. Good job.

  1. Why did you use all these gnd cables ? You can connect all the leds gnd together and then use a single brown cable to connect it to the board. There is always one led on. so no need to worry that there will be a high current request. I also advice you to connect a resistor to the gnd of the leds

    1. It’s a little complicated, and partly to do with the fact that I was initially planning to drive the LEDs via a transistor array (common anode, don’t want to risk case grounding). The leads are not very long and in the end it seemed just as easy and tidier to run individual cathode leads.

    1. With my Canon EF 50mm f/1.8 II plastic fantastic lens, and a wide lens aperture. A wide aperture gives a narrow depth of field. The pros call the background blur effect “bokeh”.

  2. nice work! one note on: “If the opto’s NPN transistor collector is connected to V+, and base connected to ground”

    i think you wanted “emitter” instead of “base”.

  3. Very Very neat project, i did one for my case and it looks fabulous!
    Hope to see more great things from you! Cheers!

  4. nice hack, congrats on getting it featured on HaD.

    i did have a thought, what about using RGB LEDs and having the colour determined by the speed of rotation? that would look awesome and only needs a very minor change in the base circuit with the integrated signal from the activity input determining the colour (via ROYGBIV) using diode logic and an LM3914.
    also gets around the need for resistors as the ‘3914 controls current directly.

  5. Nice project but it has a flaw, you dont have any current limit to the leds and this can cause problems for both the leds and the cmos 4017

    I suggest that you cut the ground common to the leds and fit a 680 Ohm resistor

    This mod will increase the life of the 4017 and leds at the cost of reduced brightness

    1. The 4017 can only source 4mA on a 5V supply (and I measured it to be sure), and up to 10mA at higher voltages, so is it current spikes or something you’re worried about? My reasoning was that 4 mA is well within the tolerance of the LEDs and 4017. But maybe there’s something I don’t understand, so please add a resistor if you want.

  6. I really like this project and I think it is just the mod I want to spruce up my case. Now I am off to find the parts! Good work!

    1. I finally built this but I have two leds that won’t light up. q6 will never light and q1 only lights every once in a while. I tested both and the leds work fine. Could this be from the filtering from the .47u cap?

      Also, what caps would you recommend for the ‘trailing’ effect Ced suggested?

      1. Sorry for the late reply, I have not been checking the comments. I’m not sure what the problem is there, but it could be poor connection to the 4017 pins. This often happens to me with ICs plugged into a breadboard. Check the continuity between each pin and the circuit board. You could also try the circuit without the cap, or change its value. Lastly, you could try driving the LEDs with transistors. I have added a circuit for this to the article above.
        With regard to the fading effect, I did some experiments and found that 5V is not sufficient for a good fade. You need to power the circuit from the 12V supply and adjust things accordingly. The value of the fading caps depends on how fast you want the fade. I found around 100 micro Farad to be good in tests, but you should experiment. This does add a lot of components as each counter output must drive a transistor with a current limiting resistor and LED in series between its emitter and ground. The fading capacitor is connected between the emitter and ground in parallel with the resistor and LED such that it charges when the transistor (and LED) switches on, and then discharges through the resistor and LED when it switches off.

  7. Hi! Great idea for replacing activity led. I am going to built 1 too but i have a problem.
    I simulated first and everything worked ok but then i replaced the green leds with blue wich probably need more power so now they dont turn fully on. Any suggesttions to this problem? If its possible not to mess with optoisolators. Thnx!

      1. If there is no other solution i can reverse but i prefer this way. Thnx for the comment. Any other solutions?

  8. Hello
    Let me first send mine congrats to you for this great page.
    But I am looking for something I believe is more simple.
    I just want to connect say 10 led’s to the HD activity pin connector on the motherboard.
    I believe I cannot do it directly since the motherboard shouldn’t that much juice on the pin connector.
    Can you please propose a circuit for this purpose ?

    Thank You

    José Machado

    1. Hi,

      I think you might be able to get away with driving 10 LEDs directly via an optocoupler like the 4N25, if you use an LED array like this:

      circuit for 10 LEDs

      The current draw should be just below what the optos’ NPN transistor can handle (50mA I think). Note that the LEDs are connected to a 12V supply (use a 4 pin molex plug to access the computers 12V supply). This circuit should flash all 10 LEDs when there is hard drive activity. You may have to adjust the resistor values depending on the LED forward voltage and desired LED current. I’ve based this on Vf of 3V, and current of 15mA. Use an online LED array calculator to get the values.

  9. Thank you for your reply
    I am think of using led strips that works directly with 12v.
    But I believe that I need more than 50mA so can you suggest a replacement for the 4N25 that can handle higher currents than 50mA ?
    Than You


  10. I just tested the version you propose to me and it works fine with the led’s stripe.
    But now I have the same problem as your first version.
    It blinks to fast.
    Do you think I can put the capacitor as in your second version as a cut off ferquency ?
    once again thank you a lot for your input.


    1. Hi Jose,

      So what is it you want to do with your LEDs? Do you not want them to act like 10 HD activity LEDs, but rather to just steadily blink on and off when there is HD activity? If you can describe exactly how you want them to behave I might be able to suggest something. To add a low pass filter as in the spindicator, you would need something that switched on at a certain voltage level, such as a logic gate. You could then use this to switch a suitable transistor (e.g. a 1 amp NPN) which would drive your LED array.

  11. Hi, first off, let me say that this is a great project ! I would like to build one using 12V and a fading led effect.
    you said “The fading capacitor is connected between the emitter and ground in parallel with the resistor and LED such that it charges when the transistor (and LED) switches on, and then discharges through the resistor and LED when it switches off”.I am just not following this, can you post a drawing to this effect ?
    Also, how do I calculate the value of the current limiting resistor for the leds ?
    Thanks in advance.

    1. Hi,

      Sorry I’ve been very lax about checking for comments, and missed your questions. I have since made another spindicator with fade capacitors, so what I will do is write a short blog about it and include a circuit diagram. Regarding calculating LED current limiting resistor values, there are web pages that will do it for you such as this one, or for a single LED, just use R=V/I where R is the resistor value, V is the supply voltage minus the LED forward voltage, and I is the desired current (usually 10-20mA).

      Once again, sorry for not replying sooner.

      1. Please please please post the updated project! I absolutely love this type of indicator and would love to see the updated project!

  12. Hello Harvey, hope you well and in good health. first off congrats on a super circuit! i have a few questions if you can help it would be greatly appreciated.

    1. is it possible to get the signal directly from a sata drive? i see image reference above to the sata spec. digging around so far leads me to believe Pin 11 is used for led signal or staggered drive spin up and also not all drives support pin 11 led activity. it possible to use SMD leds by creating a custom pcb to mount them on along with the driver circuit?

    I am in the middle of planning a case mod and would love to use this circuit and adapt it for my needs with your help if you dont mind? naturally all credit will go to you for your design?

    any help would be greatly appreciated.

    Thank you in advance

    kind regards,

    1. 1. No, old IDE drives had a reserved pin for a status LED, but newer SATA drives are not equipped with this pin and so the status LED is done by the motherboard. That said some hardware raid controllers have a status LED for each HDD.

      2. Electrically there is no reason that shouldn’t be possible but SMD LEDs are much less forgiving with current. All SMD components are generally just small versions of the same thing (smaller means less heat dissipation, lower currents, and more strict voltage requirements), so long as you stay within the operating specs they shouldn’t be any different. That said since your asking these questions I’ll assume you haven’t worked much with them before, and I’d caution you as to the difficulties associated with soldering such small pieces.

  13. Just a thought but what if you tried something like this with a 555

    It would count at the slowest rate determined by R1+R3 and at the fastest rate determined by R2+R3.

    This way the hardrive light can be thought of like a duty cycle.

    Just a thought of course.

  14. What a great project!

    It is one of those ingenious yet simple projects you want to build right away and it’s as close to instant gratification as it ever gets – would only take a couple of hours to build. I think everyone who’s started building electronics back in 80s or 90s, when not everything was done on an MCU, has a handful of 4017s or similar decade or hex counter ICs just sitting there waiting to be discarded. What a great use for an old IC!

    As a practical question though, does anyone know where to get semi-transparent 5.25″ bay covers? Drilling the circular pattern seems to be a bit less fun than just making them shine through a solid panel.


  15. Heya i’m for the first time here. I came across this board and I to find It truly helpful & it helped me out much. I’m hoping to give something again and help others
    such as you helped me.

    1. Thanks for your kind comment. It is satisfying to put something on the internet that might be of interest to others.

    1. Dziękuję. Awesome work. Keep on creating and sharing!

      P.S. Do you write Android apps by any chance?

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