Persistent Counter Recommendations please

Thread Starter

KevinSRussell

Joined Mar 11, 2019
40
Chaps

I am building a Floor Piano. I'd like to record and display a count of the notes that have been pressed. I think I need 6 digits.

I imagine a red LED counter, with a battery.

The Keys input is 3V to trigger the counter.

I'd like the display to turn off when the Piano is turned off (9V)

As always, any advice is gratefully received.
Kevin
 

ian field

Joined Oct 27, 2012
6,536
Chaps

I am building a Floor Piano. I'd like to record and display a count of the notes that have been pressed. I think I need 6 digits.

I imagine a red LED counter, with a battery.

The Keys input is 3V to trigger the counter.

I'd like the display to turn off when the Piano is turned off (9V)

As always, any advice is gratefully received.
Kevin
No idea of any commercial products, but a DIY build will require BCD counters and decoder/drivers to suit whatever displays you end up using.

the 7490 is long obsolete, but this was replaced by a dual unit - possibly 74290. The CMOS 4511 is one of the alternatives, the 4518 might be a counter decoder - but my memory isn't getting any younger.

A PIC or AVR is lots less soldering - but you won't have enough pins unless you multiplex the displays.
 

dl324

Joined Mar 30, 2015
16,644
Your requirements are unclear.
  1. Do you want this count to be maintained across power cycles?
  2. Do you want a different counter for each note?
  3. What is the purpose of the battery for the "red LED counter"?
  4. Why is the counter trigger 3V when the piano operates from 9V?
 

danadak

Joined Mar 10, 2018
4,057
Is the floor piano keys already wired in a linear fashion or muxed ?

Linear meaning each key wired to a corresponding logic input, like
10 keys 10 inputs.

How many keys ? Full piano set, 88 ?



Regards, Dana.
 
Last edited:

Thread Starter

KevinSRussell

Joined Mar 11, 2019
40
Yep - 6 digits. I probably need to build one, or at least by an OEM counter as I don't want the buttons, reset and other gubbins that comes with a pre made Counter.
 

pmd34

Joined Feb 22, 2014
527
Hi Kevin! Still building that piano! I guess for a counter you really need to use some form of micro-controller or programmable device. (As it will get a bit bulky with individual logic gates.)
I needed a counter myself recently, and opted for using one of the Altera Max II programmable logic devices. I'm a stickler for using atmel avr 8 microcontrollers, but it can be somewhat laborious driving 7 segment displays, and if you have too many characters you get a noticeable flashing, and the display can be dim (and I also need it to be very fast in this case). This is what I ended up with:
IMG_20190327_132414.jpg

The programmable logic, takes a bit of getting into at first, but the software is free ("Altera Quartus"), and the ICs and programmers can be got very cheaply from china:
https://www.aliexpress.com/item/5pc...80.html?spm=a2g0s.12269583.0.0.75f122adDUw8FZ

https://www.aliexpress.com/item/USB...870.html?spm=a2g0s.9042311.0.0.27424c4d1vi2zP
This chip has basically been programmed with some cascaded logic counters, and seven segment display drivers (so the displays are on all the time and not strobed). It could be a good solution for you also, as you can "OR" all your key input signals, very simply internally, and there is no shortage of pins on the ICs.
 

Thread Starter

KevinSRussell

Joined Mar 11, 2019
40
@pmd34 Hi! Yep - still building the Piano, and asking for your advice! I have all the main components and the Polycarbonate arrives on Friday so I may have a single keyboard module (1 octave, 12 keys) by Sunday night!

Thanks everyone for the Advice above - I'll look into it.
 

AnalogKid

Joined Aug 1, 2013
10,943
I needed a counter myself recently, and opted for using one of the Altera Max II programmable logic devices.
I'm a *huge* fan of programmable logic. I always start there, and move to uC only when necessary. I baby-ducked on Lattice and they're still my fav, but I've done both Altera and Xylinx. As you noted, this project is perfect for a CPLD.

And, *very* nice board design. What was the overall project?

ak
 

Thread Starter

KevinSRussell

Joined Mar 11, 2019
40
@AnalogKid

As you will be aware, Youtube recommends videos. A few weeks ago it recommended the Clip from the film "Big" where they play Chopsticks on a massive Floor Piano. I started investigating how much it is to buy one, then when I couldn't find any (apart from the rolled up ones) I looked into building one. The two or three projects (instructables et al) weren't viable or used Arduino/Raspberry Pi.

I was sure it would be easier to buy a Music Keyboard, remove the PCB, reverse engineer the Keyboard PCB and enlarge the design while sticking the PCB, LED Driver etc in a Project Box.

After some fantastic advice from this forum :rolleyes: I have created a single prototype Key from MDF and on the weekend I ordered the Materials. So far it's cost me around £600 including a Bench saw! On the plus side, it costs £1,135 minimum to hire one for the day!

The Kids can't wait...

EDIT: The Counter is just for curiosity, not essential.
 

pmd34

Joined Feb 22, 2014
527
Hi AnalogKid... its some comments from a previous thread as you might have seen :rolleyes:
Thanks for the kind comment! I wanted a "high-speed" (ADCMP600) pulse counter with (adjustable threshold), for counting pulses from a silicon photo-multiplier.
It was also one of those items, that I have occasionally needed, and had no option for.. though I was able to remember what the bench-top, lab versions look like exactly!!
 
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