I was thinking of a simpler way to make a buzzer sound at a given time. For example, using a potentiometer to set the time to 1 minute, 5 minutes, 13 minutes, 22 minutes etc. Once the time has reached, the buzzer will sound.

Does this need a microcontroller for this to operate? What alternatives are there for this idea? Perhaps counters? If so, what would be a good counter for this buzzer to sound at a given time?

 

If you want the time to be somewhat accurately set, then you will likely need a micro to control it and input the time with a keyboard.
Or buy a kitchen timer.

 

If you want the time to be somewhat accurately set, then you will likely need a micro to control it and input the time with a keyboard.
Or buy a kitchen timer.

Well if thats the case, I'd just go along with using a PIC10F200. Is it that when twisting the potentiometer, I assume depending on the voltage level that it would make the buzzer sound?

 

Since your sole input is a potentiometer there really is not an accurate way to adjust this thing. So how accurate do you want it?

I don't see any compelling reason to use a micro on this. Something like a CMOS timer similar to the MC14541B could do the job to adjust the timeout over a 22:1 range.

 

Or.If you don't want to roll your own here's a fairly easy to hook up timer..http://www.amazon.com/Altronix-6062...=UTF8&qid=1421177884&sr=8-2&keywords=altronix

 

Since your sole input is a potentiometer there really is not an accurate way to adjust this thing. So how accurate do you want it?

I don't see any compelling reason to use a micro on this. Something like a CMOS timer similar to the MC14541B could do the job to adjust the timeout over a 22:1 range.

Well, what would be your alternative or better component to use instead of a potentiometer? separate buttons for different timings?

 

Basic 555 Timer and a simple buzzer? Simple single pole 5 way switch to select preset Capacitor/Resistor pairs... or as you say, use a Pot and mark a few positions.

PIC is overkill for this, as much as I love them. If I were using a PIC I'd want a display to watch the countdown too... then I'd want at least 3 buttons for reset, start/stop, add minutes...

Depends if you want to go basic and old skool, or all fancy and start using blue LEDs...

 

Well, what would be your alternative or better component to use instead of a potentiometer? separate buttons for different timings?

HOW I would do something depends on WHAT I am doing.

You state your range, resolution, and accuracy and I will give a way/ways to do it.

Here is a timer I made that is in the public domain.

I've also made timers that live inside some MIL-PRF relays. While I can't provide the schematic (I don't own it) I can answer lots of questions.

 

HOW I would do something depends on WHAT I am doing.

You state your range, resolution, and accuracy and I will give a way/ways to do it.

Here is a timer I made that is in the public domain.

I've also made timers that live inside some MIL-PRF relays. While I can't provide the schematic (I don't own it) I can answer lots of questions.

Basic 555 Timer and a simple buzzer? Simple single pole 5 way switch to select preset Capacitor/Resistor pairs... or as you say, use a Pot and mark a few positions.

PIC is overkill for this, as much as I love them. If I were using a PIC I'd want a display to watch the countdown too... then I'd want at least 3 buttons for reset, start/stop, add minutes...

Depends if you want to go basic and old skool, or all fancy and start using blue LEDs...

Thanks for the reply. I actually thought of using a 555 timer, BUT my buck boosts out around 2.5 volts. It's not enough to power the 555 timer. I don't recall how many volts a CMOS 555 timer would turn on. I assume lower voltage?

My idea was basically a count down timer. So basically if I was to set the time at 15 minutes (Position 1 of the potentiometer), the buzzer doesn't go off until 15 minutes has reached etc.. 30 minutes (Position 2), 60 minutes (Position 3)....

 

CMOS logic chips will need 3V and above to work. There are some micros that work down to 2V but then you have the problem of finding a buzzer that buzzes at 2.5V.

Any '555 based timer has the problem of needing a large value cap with very small leakage, as the time interval is based around one RC time constant. Devices like the MC14541B use an oscillator driving a digital counter to get long times with smaller (and cheaper) caps. That is what the customers orgionally used in those MIL-PRF relay timers (or a close similar chip, the number & data sheet doesn't strike the mental bell hard so I'm not 100% sure it is what was used).