How To Make MINI UPS For My Digital Clock ?

[pasanlaksiri]

Hi guys,

I make a digital clock. So now i need a back up battery for
in case of power falier. Im going to use 3.6V 300mA Rechargable Battery. ( cordless phone battery )

My clocks voltage is 5V.

So do u guys hv any ideas about How To Make MINI UPS ?


THANKS

 

[juan123]

maybe make it be trickle charged directly from the transformer from the power suppply..... that would make the battery be charged fully and at the same time work if the power died out...... sorry if this doesn't help much....i'm new.

 

[audioguru]

One of my clocks has a big filter capacitor that keeps its internal oscillator running and the timing IC working. The LEDs are turned off to reduce current.
Another clock uses a 9V battery which goes dead in a few months.

A 3.6V battery probably won't run a 5V clock.

 

[pasanlaksiri]

One of my clocks has a big filter capacitor that keeps its internal oscillator running and the timing IC working. The LEDs are turned off to reduce current.
Another clock uses a 9V battery which goes dead in a few months.

A 3.6V battery probably won't run a 5V clock.

No Friend, U wont believe I run it from a 3V CR2032 battery for two days as a test. ( of course without LEDs ) Results is superb. CLOCK time is running nicely and that battery is also good after two days.
**broken link removed**

 

[Krumlink]

Try a 1F memory backup capacitor, it is designed for these kind of things (I would assume).

 

[dknguyen]

No Friend, U wont believe I run it from a 3V CR2032 battery for two days as a test. ( of course without LEDs ) Results is superb. CLOCK time is running nicely and that battery is also good after two days.
**broken link removed**

THen why do you need a mini-UPS when you can just use the battery?

 

[kchriste]

I think he just needs a resistor to charge the battery from the 5V line in parallel with a diode to power the clock circuitry when the power is off. This assumes that the 5V regulator doesn't mind having 3.6V on it's output when it is powered down. It also assumes that the 5V reg won't drain the battery too much when the power is off.

 

[pasanlaksiri]

I think he just needs a resistor to charge the battery from the 5V line in parallel with a diode to power the clock circuitry when the power is off. This assumes that the 5V regulator doesn't mind having 3.6V on it's output when it is powered down. It also assumes that the 5V reg won't drain the battery too much when the power is off.

Thats exactly what i want

 

[pasanlaksiri]

When im googleing for it. I found this.

**broken link removed**

 

[audioguru]

DO NOT try to charge the CR2032 lithium non-rechargeable battery that is shown. Its datasheet lists its max reverse current is only 1uA.

If you try to charge it then it might explode or catch on fire.

 

[pasanlaksiri]

DO NOT try to charge the CR2032 lithium non-rechargeable battery that is shown. Its datasheet lists its max reverse current is only 1uA.

If you try to charge it then it might explode or catch on fire.

Holly amigo! who will ever do that

But THANKS U VERY MUCH FOR THE WARNING

 

[HiTech]

No Friend, ...........

Hehe hehe, Audio Guru has a "friend"!

 

[pasanlaksiri]

Hehe hehe, Audio Guru has a "friend"!

Hi hi heee

 

[ronsimpson]

This is a very interesting thread. I just tried my radio clock and it uses the 60hz power line frequency to count time. Adding a battery keeps the LEDs light but the time does not advance. This is not too bad. If the power goes out for 10 seconds the clock is late by 10 seconds. Much better than 12:59:59 blinking!

 

[HiTech]

Hi hi heee

From the looks of your avatar, thank you but I have enough friends. Audio Guru, being a Canadian fella, wouldn't mind an extra friend or two for warm conversations on those cold Alberta Clipper evenings!

 

[pasanlaksiri]

From the looks of your avatar, thank you but I have enough friends. Audio Guru, being a Canadian fella, wouldn't mind an extra friend or two for warm conversations on those cold Alberta Clipper evenings!

Oh I Seeee

 

[audioguru]

I think the Pasani guy is too far away from the cold of Canada.
The last few winters have been much milder than in the good old freezing days.

 

[blueroomelectronics]

What's better than a battery backed up clock is a WWVB clock (Radio signal time setting) No battery backup required and very very accurate.
http://www.amug.org/~jthomas/gc1000.html
**broken link removed**
Pretty Heathkit GC-1000, pretty sure that blue LED isn't factory...

 

[Sceadwian]

Even a WWVB clock won't go off without power... Completly useless for an alarm clock that needs to be relied upon in the event of one.

 

[blueroomelectronics]

The OP never mentioned alarm clock. If that's all that's required buy a watch with an alarm.