"Simple" hour/minute binary clock?

Tried

?

Are you looking to buy this unit as a kit..... or schematics for a 74xx/40xx logic..... or some microprocessor schematic.....

By the looks of your description, you already have a spec.

Looks like an opportunity to design your own.

Pick a single chip controller with enough pins to drive the number of LEDs you want and start writting code.

easy

donald

ISTR Scientific American had one which had wooden toggling displays.

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Arguably the easiest way to do this in hardware would be to use a
4020 to divide the 60Hz mains by 3600 to get 1 minute ticks, then to
use those ticks as clocks to drive a 4040.  The 4040 could drive
low-current LEDs directly, and a decode at 60 minutes could be used
to drive a 4024\'s clock input, which would give you binary hours out
of the counter. Finally, a decode at 12:60 would reset everything to
00:00 when the sequence would begin anew.

Would you like a schematic?

12:60? Don't you mean 11:60?

Michael

Popular Electronics, or Radio & Electronics magazines had a DIY project for this back in the '70s.

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Service to my country? Been there, Done that, and I\'ve got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

No. You are at 12:59 and when you hit 12:60 you go to 1:00 instead.

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Yup, duhhh... Thanks :-)

Right.

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John Fields
Professional Circuit Designer

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Oops...

Like Homer said, 12:60 will reset to 1:00. (Not 00:00 as I wrote
earlier.)

"Homer brain beer well not work without"

John Fields wrote: (snip)

Actually, yes! Please!

My experience with electronics is somewhat limited - I've done some projects, but they've all been simple "hack it apart and change it" stuff, mostly on old video game systems (turning my NES into a portable system, making a light pen for my Commodore 64, etc.). I can read a schematic, and I'm sure any symbols I don't know can be found online.

I've found a few projects which are close (ticking out time using an array of chips/crystals rather than using a BASIC stamp or other programmed chip to count off time, which I've done before & didn't like), but all of them are much more complex than what I'm looking for (a twelve-hour hours/minutes display in two rows), usually including dozens of LEDs to count out 24-hours and even seconds. I'd like to see if I can make one running off batteries rather than A/C, which means I'd need a crystal since I wouldn't have the 60Hz line.

Like I said, though, my current experience is too limited to allow me to be creative, since I don't have much idea of where to start.

I'd start from the back-end so you have something to look at.

Get a 74HC4040 and hook up some LED's to the outputs. Ground the reset pin. feed any kind of square wave signal or pulses into the clock input. Watch the pretty LEDS count up.

That will be straight binary counting, which can get a little tedious to decode.

If you want BCD counting, with 8-4-2-1 lights for each decimal digit, then use a 4518, that's two decimal counters. But this will count up to 99, which is inconvenient.

To get it to flip over at 59, you need to detect the "6" and reset with that, you can do with an AND gate, say a CD4081 or two gates of a

74HC00.

Then to get your 1 cycle clock,I'd use another two 74HC4040s and a

32,768 hz crystal. The crystal you can get to oscillate with one of the NAND gates in the 74HC00. Google for "cmos crystal oscillator" for examples.

Have fun!

Thanks for the suggestions. I don't think I was clear on what I wanted to build, though. Most of the projects I'm finding have a separate string of four binary numbers for each place:

O O O X Tens of hours X X X X Ones of hours X X X X Tens of minutes X X X X Ones of minutes X X X X Tens of seconds X X X X Ones of seconds

With the Os being empty spots where no LEDs are needed. What I wanted to make is similar to a wristwatch I found online, with just two rows of places 8, 4, 2, and 1, the top row being hours and the bottom being

32, 16, 8, 4, 2, 1 for minutes. A link the image is here:

Maybe I'm just not clear on what you're explaining since I'm having trouble visualizing (like I said, I can read a schematic, but since I don't know much beyond that, I can't always "see" it when its spelled out).

Assuming you want the clock shown

It'd be quicker and easier to use a PIC chip.

Those guys do this:

1 ppm clock ----- [BCD 0-59 counter] ----- [BCD 0-12 counter] 10's 1's 10's 1's

All you want is this:

1 ppm clock ---- [Binary 0-59 counter] ---- [ binary 0-12 counter] 5 bits binary 4 bits binary

So, figure out how to get your 1Hz clock, then use three binary 4-bit counters, and some gating logic to get the minutes to wrap at 60 and the hours to wrap at 12.

Good Luck! Rich

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OK. I\'ll post a schematic to alt.binaries.schematics.electronic
tomorrow, but since Google won\'t let you access binaries through
Google Groups I\'ll email it to you as well.

BTW, what battery voltage do you want to use?

schreef in bericht news: snipped-for-privacy@h48g2000cwc.googlegroups.com...

Hm... So your requirements are straight forward:

- One X-tal ocsillator

- One divider/counter to bring the oscillator frequency down to 1/60Hz

- One divide by 60 (minutes) counter. All six ouputs to drive a LED and the rollover to clock the hour counter.

- One divide by 12 or 24 (hours) counter, all four or five outputs to drive a LED.

- All powered by battery.

You can get almost every X-tal you want if only you are willing to pay for it. Cheapest ones I'm aware of are in the simple quarz clocks. They contain an oscillator and divider that gives a pulse every second alternating on two different outputs. Powered by a 1.5V battery you have a 1/2Hz clock. You only need a transistor the amplify the 1.5V pulse to the level required by the subsequent logic.

As you want binary output you will need three binary counters. But as the range of the counters is not a power of two, you will need to reset them once they've counted to 29, 59 and 11(or 23) respectively. That means for the divide by 30 counter you should detect the value 29dec or 11101bin and reset the counter at the next clockpuls. IMHO best counters for this purpose are the classic 163 counters. Of course the CMOS version so CD40163B for instance. The divide by 30 counter requires two of then plus a four input NAND gate for the reset. Similar for the minutes counter. Decode 59dec or

111011bin to reset the counter. If you want a 12 hour clock, you need only one CD40163B and decode 11dec or 1011bin for the reset.

At 5V or 6V the CD40163b can provide the 1mA required to drive a low power LED. You can use buffers to increase this current but for a battery powered circuit I'd stick on the low power LEDs.

petrus bitbyter

(snip)

I really appreciate all your help on this! A big part of this project and a few other small ones I'm working on is to take my ability to read schematics and build something from them and actually learn what some of these components/circuits do so I can be a little more flexible and creative on some larger things I want to build down the road.

Battery voltage doesn't matter, whatever will drive the circuit. I'd prefer to not use one of the huge 12v flashlight batteries though, since I wanted to hook a few batts up in parallel and mount clips to the circuitboard so the whole thing can be hung on a wall. 9v maybe? The chips will need a 5v I assume (everything I've been working with so far does). To drive those, I've cheated and used 5v power adaptors from Radioshack, but like I said I wanted this to be a self-contained thing.

Thanks again!