1 minute Timer circuit

Status
Not open for further replies.
K

kiks

Member level 1
Joined
Jun 1, 2004
Messages
35
Helped
3
Reputation
6
Reaction score
3
Trophy points
1,288
Activity points
349
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.
 

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

Thanks anyway
 

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!
 

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:
 

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

    E

    empser

    Points: 2
    Helpful Answer Positive Rating
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.
 

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

Ken
 

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

Ken
Click to expand...

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

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

Hi,

For accuracy of microchip pic internal clock it's on the data sheet:
Precision Internal 4 MHz oscillator factory calibrated to ±1%
Click to expand...
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.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…