? about my clock project

[jbelectric777]

I thought all I needed for my clock was a 555 pulse, a decade counter and a comparator. Am I missing an IC like a decoder or something ? I have the clock pulsing 1s from the 555 then I have the counter which is outputting 0-9and then I thought the comparator de coded and lit my segments.

 

[jbelectric777]

Now I reduced the resistance for the 555 trigger and I still don't have a clock but I have one heck of a tracer light goin on..... pretty fun actually, my mother in law saw it and wants me to put led's in her Christmas picture using clear extra bright led's to simulate snow falling (or white led's if they make em ) how long would a new 9V battery last with a pulse every 1-2 seconds, I read somewhere a 9V battery has a 500ma hour rating so is it correct to say that the battery could output 500ma for one hour ? and just divide the ah rating by the led's ma rating ?

 

[k7elp60]

A digital clock has divide by 10 and divide by 6 counters for the seconds and the minutes, and a divide by 12 or divide 24 for hours depending on wether you want a 24 hour or a 12 hour clock. Some counters have built in decoders for seven segment displays.
The MAH rating for a battery is its capacity, and it always does not mean you can get that amount of current out of it in 1 hour. It depends on the chemistry of the battery. For example generally Ni-Cad can supply the rated current for on hour. Lead-Acid batteries are at the 20 hour rate.

 

[audioguru]

You forgot to attach a schematic of your circuit so we don't know anything about it.

The max current for ordinary LEDs is only 30mA. The max current for seven-segment displays is less. If all segments of a seven-segment display are lighted with 10mA each then the current is 70mA.

A little 9V alkaline battery is 9V when new. With a 70mA load its voltage will drop to 8V in 1.5 hours. The display will look a little dimmed.
At 6 hours the voltage will be about 7.2V, at 9 hours it will be about 6.2V.
The display will be dimming and the current will be reducing so the battery will last a little longer than I just described. But how dim is too dim?

I used a low-dropout voltage regulator on some of my 9V LED projects so that the LEDs stay bright as the battery voltage runs down to 5.4V. Ordinary 7805 5V regulators stop regulating when their input voltage is below 7.5V.