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1 minute Timer circuit

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kiks

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Does anyone have a circuit for a low cost 1 minute precision timer circuit? I have built a timer with a 555 ic. It is ok but the accuracy varies with time.
 

kiks

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If I wanted to buy one I would not have asked on the forum!! I want to make one.

Thanks anyway
 

memarian

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Hi,
If you need precise timing,using 555 is not good. your timing is depending on a Capacitor Value that will change with temperature easily (you can decrease the temperature sensitivity by using NPO Capacitors),also other parameters will change with temperature.

you have other solutions , like buying a real-time clock IC. easier solution will be using a 32768 Hz Crystal (Clock Crystal , 2^15=32768 ) . you can easily design a simple oscillator with that and with a 15 bit counter, you will have 1 second trigger, with another counter you can count seconds for reaching anytime (1 minutes,..etc).

Good Luck!
 

IanP

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Another option is to use the simplest microcontroller (8pin DIP, same as 555) PICAXE-08 ..
Simple instruction such as WAIT 1 is an exuivalent to 1sec, and WAIT 60 =>60sec=1min ..
Have a look at this Circuit Notebook (aricle on camera recorder):
Silicon Chip Online - Circuit Notebook

IanP
:wink:
 

cent24.3

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May be a low cost pic10f206 and the appropriate program will be accurate enough (with internal 4MHz clock).
 
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Tahmid

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Hi,
When you bring in "precision", I would prefer to use a microcontroller. Doing the same with discrete circuitry is possible, but can make the circuit complex. In that regard you can use an ATtiny, the ATtiny10 is I think the cheapest or a PIC12. Internal oscillator is not accurate enough, so an external crystal is recommended. This is quite precise. You could use the PICAXE as suggested, but I don't know much about those.

A program in mikroBASIC for this could be:
Code:
program something

main:
   'Initialize I/O and anything required
   'Wait for trigger
   delay_ms(60000) 'Waits for 60000ms = 60sec = 1min
   'Do whatever you need
end.

That's just an example and nowhere near a complete code, which by the way isn't too hard either.

Hope this helps.
Tahmid.
 

KMoffett

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Guys!...kiks hasn't been back since they started the thread 6 months ago.

Ken
 

memarian

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Guys!...kiks hasn't been back since they started the thread 6 months ago.

Ken

Hi Ken,
This thread has been started 2 days ago, 5th of November. The date is in European format :idea:(dd-mm-yy) not US format.
 

Lloyd Lagace

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How about the XR2204 Programmable timer. Time base is R/C but cheap and reliable good repeatable accuacy.
 

cent24.3

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Hi,

For accuracy of microchip pic internal clock it's on the data sheet:
Precision Internal 4 MHz oscillator factory calibrated to ±1%
May be 1 minute ± 0.6 second is enough for kiks's application.

If you don't want mcu based solution I would say I really like daretodream25's solution. It's able to be feed directly by a 9V battery and it's a low current consumption solution.
 

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