Hi,

Am sure there is a very easy answer to this! I'm getting back in to electronics and need some help with how to construct a circuit.

Essentially I am looking to build an LED clock which has an "analogue" look to it. I've done a normal clock a few years back using 4017 ics (so have a basic electronics understanding) but they're not of use this time.

If I take the seconds display which will explain this best, what I want is to, over the course of 1 minute, light 60 LEDs around a clockface. Each LED will remain lit until second "zero" is reached again when the display resets.

Thus:

time display
0 blank
1 LED 1 illuminates
2 LED 1 remains illuminated and LED 2 illuminates
.
.
.
59 LEDs 1, 2..., 58 remain illuminated and LED 59 illuminates
0 LEDs reset

With minutes and hours I will do something similar though with only one LED lit at any time.

My question is, is there an easy way to achieve the above either with transistors or basic logic gates? I'd like to build this using readily available chips without having to go down the PIC/programming route.

Any help greatly appreciated.

Dan

 

As I suspect you already know?, a PIC would make this project a LOT simpler, and assuming it's not a school assignment (but a practical project) would be the obvious way to go.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

It is definitely buildable without a micro. chain 6 4017s for the minutes and 2 or 3 for the hours (depending on 12 vs 24). getting the effect you want for the seconds could be done with 8 cascaded serial-in, parallel out shift regs. The input is one. Reset when the 60 position sees a 1. look at the 74hc595 but there are others. Chip resets would be generated at the appropriate places. Also, you would need to determine if you can drive all those LEDs from the chips, You might be able to get away with high efficiency LEDs and no drivers but check the chip specs. I'd use 74HC logic as those can drive a fair amount of current (for logic devices).

 

Of course it's 'buildable' - but is it practical? - you've already suggested chips in double figures, a micro-controller is a far more practical method.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

The OP expressly said he didn't want a uC solution.

If the builder has no uC skills (and no desire to learn them), then what I suggested is the easier approach. Also, given that he has to wire up 144 LEDs, I suggest that the extra chips aren't making the complexity dramatically higher and, in fact, the wiring may be easier since the SR and decade counters can be placed near the LEDs with a common ground and one wire to each LED. With a uC, he'd have to matrix the LEDs - 11x10 or perhaps several matrices. 144 pairs of wires. It would be a real rat's nest of wires given LED placement.

I usually prefer micros but if I were building this, I might still use SRs.

 

Philba - that's exactly what I was looking for. Many thanks for your help...

Dan