Schematic for a variable timer

[tnvoon]

Hello,

I need a schematic for a timer circuit (preferably using a low voltage 555 timer) that will give an output at 10 minutes and then another output 1 hour later when triggered. The output will be used to drive a beeper. Supply voltage for the whole circuit is to be at 1.5V and power consumption should be minimal since the whole circuit will be battery-powered. Timing accuracy is not critical. A +/- 2% error is acceptable.

Any help given will be much appreciated.

Nang

 

[nbucska]

If VERY large number : Xtal controlled digital custom circuit like dig. wristwatches. $$$$$$

If small number : trade off more battery . Use dc-dc
to raise VTG, use XTAL/CMOS COUNTER.

Are the times fixed or programmable ? How much battery lifetime is OK ? Volume limit ?

Need schematics ? Give a FAX#. <nbucska@pcperipherals.com>

 

[melone]

Why don't you just look at the 555 timer app notes? Actually, you can use the 556 (dual 555) IC.

 

[nbucska]

Hi melone:
Not with 2% accuracy ! <nbucska@pcperipherals.com>

 

[tnvoon]

Thanks for the feedback.

What I need is something simple and low-cost. Two months battery life at least. I'm looking at button-type batteries as used in watches. The circuit doesn't need to be active all the time. The circuit only turns on when a push button switch is pressed. And the alarm goes off twice at the fixed times of 10 min. and then 1 hour later and the circuit should then turn off.

Nbucska, my fax# is:
Country code:60
Number is: 4-2628690

Thanks.
Nang

 

[nbucska]

One measurement sequence takes 70 minutes. HOW many
sequences do your battery have to survive ?

With CMOS logic, you will need about 4 or more IC-s
Do you have enough space ?

It could be smaller with microcontroller if power is acceptable.

If you need only one, why can't you use larger battery ? <nbucska@pcperipherals.com>