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Binary Clock

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New Member
Oscillators and Counters

What's the question :?:

Do you want an oscillator to give a clock pulse train to a binary circuit?
Do you want a series of square waves, each at half the frequency of its predesessor?
Could it be a clock that displays time of day in binary (weirdo of the week award)?

Will it be TTL (0v to 5v) compatible or for CMOS (you choose the voltage) or relay logic (capable of hundreds of mA, could be mains voltage) or what?


New Member
Answer #3 would be the one

I would like to build a clock that displays the time of day in binary.
Would like to run it from a 9v battery.


New Member
24 hours in binary?

Assuming you only want minutes (no seconds) then the circuit will need to count to 1440 (decimal) or 10110100000 (binary) - 11 bits.
If you want seconds as well this becomes 86400 (dec) or 10101000110000000 (bin) - 17 bits.
The above assume 24 hour(!) format and true binary - not binary-coded-decimal - which would give bigger numbers.

If an oscillator is set to run at 1 pulse per second then counting will be easy - just use normal (CMOS for 9v) logic counters, each stage of counter driving the next and an output of some sort (an LED? - short battery life!)

Assuming you build this device I wonder how long it will take to work out that 1011010000 is lunchtime?

Jay E. Morris

New Member
Can't believe this hasn't been answered. But I've been looking across the net for plans for a binary clock also. I can find the clocks with no problem (http://www.computergear.com/binaryclock.html) and I have found kits (anywhere from 2 to 3 times the price of the clock - wasn't the idea of kits the fun of putting it together AND it was cheaper?) but cannot find a simple layout.

While I weld a mean soldering iron, I'm not an EE.

So if anyone has one, how about posting?


LApprenti Sorcier

New Member
Hey! I know what you want

I've seen thos clocks, i want to build one too, i know how to do the clock, but i need to find a good (precise) oscillator for the seconds!

In junior high i did this clock with some 74**'s but the oscillator was a 555 and of course a pain in the ass to adjust it, it would run early a couple of minutes every few days...

All we have to do is get rid of those 7447 (Digit encoders) and use the 7493 outputs directly to get our bits... Also, modify the reset inputs for the last 7493's to get militar or standard time...

Could someone please comment on the circuit (i.e. if we should be using something better than 7493... etc.)

And please give us a precise 1 Hz oscillator!!!!

I'll redraw the circuit and send it as we should use it soon.

This is what it should do:




LApprenti Sorcier

New Member
Sorry for not having posted the diagram yet...

I've had a lot of work, but i'm working on it.

Anyone, ideas on the "seconds" oscilator? thanks.


Active Member
I would use a oscillator module (give it VSS; VDD, and a fixed freq comes out)...

You won't find one of 1Hz tough. But you can divide the freq. with counters

LApprenti Sorcier

New Member

I'm already getting feedback on the oscillator to use...

Should have everything ready soon.

LApprenti Sorcier

New Member
Power module

I've been wondering for how long would a common battery supply a circuit like the one drawn above... any idea?

What would be the most efficient means of getting those 5V?
How much current can a 7805 give me???



Active Member
Re: Power module

LApprenti Sorcier said:
I've been wondering for how long would a common battery supply a circuit like the one drawn above... any idea?

What would be the most efficient means of getting those 5V?
How much current can a 7805 give me???

If you use LED's then a battery won't last long... Leds don't really use much energy, but it's a lot of leds...

7805 can give approx. 100mA uncooled, and should give 1A cooled (but it is best you don't go that high)
It also depends on what voltage you have to start with... if you use the 7805 to regulate a 9V supply then he will be able to deliver more power then when you want to regulate a 24V supply.. simply because the 7805 will have to 'get rid' of more power and get hotter in the latter case...

LApprenti Sorcier

New Member

Actually that's what I was planning on... a 9V battery.

Do you really think it's a lot of led's?

(Note that the plans aren't doing it as somebody commented above, but as a link i included before, let me bring the image here...)

Notice the tenths and units of the hours minutes and seconds are all divided, so all that is needed is 20 leds, is that a lot???

Also, I once heard you needed like 5V to power blue LEDs is that true? or can you get them working on the usual LED voltage? what's the max current i should admit through them? through more common colored leds?

Thanks a lot![/img]


Active Member
I thought you were going to make the scematic above with 7-segments

20 Leds shouldn't be a problem...
If you give each led 10mA (+- 330ohm resistor @ 5V) then 20leds will draw 200mA. 7805 Can deliver this, but remember to add a heatsink
This is for normal leds...
If you use blue leds or other superbright leds then current consumtion will rise

LApprenti Sorcier

New Member
Ok, now, I have the 2Hz oscillator, the flip flop to divide it into 1Hz, the power source...

Will it be ok to use the 7493's? or is there a better option???



New Member
Save power

If you abandon the 7400 series and use 4029 counters you will save power
(important if you want to run from batteries)
and avoid a 5v regulator - everything will be happy on a 9v supply (but why use 9v? ... see later).

Are you planning on 12 or 24 hour format ? (or switchable???)

At 17:37.37 this display will light 14 LEDs - at 10mA/LED = 140mA
At 00:00.01 there will only be a single LED on .... 10mA
A stack of 'C' cells may give a life of 4 days or less ...
A stack of 'D' cells might double this - 160 hours
I guess you will be buying new batteries twice a week then ?
Are you sure you want this to be battery powered ?

If you use batteries then you want to keep the voltage as low as possible -
Every LED has to have a series resistor, any resistor will dissipate (waste) energy.
The lower this dissipation is the better your circuit's efficiency,
a higher voltage means a bigger resistor and more wasted power.

LApprenti Sorcier

New Member
Sorry for te double reply...


Got the software... I'll be uploading the schematics soon!

LApprenti Sorcier

New Member

Got the software... I'll be uploading the schematics soon!

panic mode

Well-Known Member
I was thinking about doing something like that but I'm still
pondering some details. This is what I had in mind:

I would like to use AC power in normal operation and OLEDs
controlled by PIC. OLEDs (organic LEDs) would be multiplexed
and powered by PIC directly. This is possible because PIC can drive
up to 25mA sink or source. OLEDs take much less power than
standard LEDs (ca 10x lower current) so that even if all 4 LEDs
in one group are turned at the same time that would mean
2mA * 4 = 8mA. Multiplexed LEDs should be driven with higher
current so they apear as bright as if they were powered continuously.
Also note that in one group, max number of LEDs to be on at the
same time is only 3 (when displaying number '7').
So 3mA * 3 = 9mA per group which is well under 25mA limit.
This way no additional transistors are needed for multiplexing.
Whole circuit can be one PIC with Xtal and two capacitiors,
LEDs, one diode, 6 resistors, two buttons to set time,
pair of rechargable batteries and little 3V PSU. I don't think
this can get any simpler without sacrificing some functionality.

Even with lowered current requirement, PIC would be only thing
running from (trickle charged) 2x1.5V batteries if the AC power is off.
(thats where diode and two resistors are planed to be used).

While batteries are full, LEDs would be cycled one group at the time
with low duty cycle at very low frequency (optional).
For example each group of LEDs would be illuminated only one
group at the time and only for one second (first display 10s of hour,
then 1s of hour, then 10s of minute etc.). After that all LEDs would
be off. This would repeat periodically (for example every 30 second
to save power). Once the voltage drops bellow certain setpoint,
LEDs would turn off completelly so I don't have to set time when clock
is moved from one outlet to another or in case of power outage (remember Big Blackout?).
Anyway, I would appreciate comments or ideas.

LApprenti Sorcier

New Member

Does anyone know the appropiate Vcc to drive and input 4029's???

Also, the diagram or info about the terminals.

How should i connect it?

Q: Do they output the same V+ they are fed?

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