I want to build a metronome that has a ring of 16 LEDs, each representing a 1/16th note.

Thread Starter

Ribid

Joined Sep 28, 2007
2
Hi, I'm looking for suggestions to do this simply. Thanks for any tips.
I want to build a metronome that has a ring of 16 LEDs, each representing a 1/16th note. Together they would constitute one measure in 4:4 time, and the LEDs would loop around the circle repeatedly. Looks like this is an 'LED chaser' type application, and I've read the posts about chasing LED's to arbitrary counts using the CMOS 4017, with special tricks to sequence which 4017 is enabled to light LED's.
I'm wondering if there's an opportunity to do this more simply, given that I have 16 LEDs? Kind of a digital magic number. Doesn't need to use the 4017.
Thanks for any suggestions.
ribid
>>>>>>>>>
In case you're interested in the application, I'll mention that not all the LEDs will have the same color. The upbeat and downbeat LEDs will have unique colors, and the quarter note LEDs will share a different color (less bright), and the rest of the 1/16th note LEDs will have another color, even less bright. I'm a drumming student and so far I'm working in only 4:4 time and this project will help me coordinate fills with the beat. I'll drive it from my function generator so I can easily change the beats per minute. I may add a BPM indicator once I get the metronome working. And maybe a bar counter that counts to 12 for 12-bar blues.
ribid


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AnalogKid

Joined Aug 1, 2013
9,956
Another option is a binary counter plus a 4-line to 16-line decoder. This has the advantage of a totem pole output stage that might be able to drive the LEDs directly. You don't say what the power source is or what logic technologies you have access to, but old, standard TTL and LSTTL parts could sink 16 mA per output. Or, more contemporarily, AC CMOS parts can source and sink 20 mA.

A different option is a pair of LM3915 dot/bar graph drivers. The datasheet shows hot to cascade them. This would be driven by a sawtooth wave.

ak
 

Alec_t

Joined Sep 17, 2013
12,743
I would be concerned that the LEDs turning on/off would cause light flashes in the frequency range (typically 5-30Hz according to the Epilepsy Foundation) known to trigger epileptic seizures in sensitive people.
 

BobTPH

Joined Jun 5, 2013
4,766
Yep, for 1/16 notes it would be right in that range. Dance music goes from about 90 to 180 beats per minute or 1.5 to 3 Hz, but 1/16 notes, would be 4 times that or 6 to 18 Hz. I would also question the usefulness of going beyond one flash per beat, to anyone used to a traditional metronome, I would think it would be distracting.

Bob
 

KeithWalker

Joined Jul 10, 2017
2,306
The flashing frequency could be a problem if the LEDs were very bright but a small, low power display would have no more effect than an audio volume bar display. The 4017/LM555 solution is certainly the simplest and easiest to implement. The last batch of miniture coloured LEDs I got from AliExpress are quite bright even at 100uA so they could be driven directly by the 4017 outputs.
 
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