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digital clock +alarm+power supply

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yousuf

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can anyone help me to find a circuit for a digital clock and alarm with own power supply ,
but without microcontrolers, using IC's

please and thank u all
 
What voltage and current?

Why can't you use the LM317? It's such an easy IC to get hold of and use.
 
well im kind of new to this field , so i really dont know much

im looking for a circuit design for a digital clock alarm ,,
 
Here's a tutorial which contains a schematic and explanation.

HowStuffWorks "How Digital Clocks Work"

I'd recommend using HC CMOS rather than TTL parts, i.e replace the 7490 with 74HC90 and the 7447 with the 74HC47 etc.
 
thanx a lot fot the information ,, but ive been through it and it doesnt contain information about alarms ?

thank you
 
It should be fairly easy to add an alarm.

You need some digital comparator ICs, such as the 74LS85 or 74LS688, and four rotary BCD switches, one for each digit.

The inputs to the comparators connect to the outputs of the counters and the BCD switches. The comparator's output will go high when both inputs are equal to each other, this sets off the alarm - connect a piezo buzzer to the output of the binary comparator.

The comparators need to be cascaded so they behave like one comparator, this is easier for the 74LS85 (it's shown on the datasheet) but you need to use four ICs, as they're only 4-bit comparators and you need a 16-bit. For the 8-bit 74LS688 but it should be fairly easy to add a gate to the P=Q outputs so the buzzer is activated when both ar low. I probably wouldn't bother with using another IC and would use a combination of diodes and a transistor, ask if you don't know how.

What's the mains frequency in your area? If it's 50Hz, you'll need to modify the circuit: change the divide by 6 counter to divide by 5.
 
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