Build alarm clock

You didn't specify analog or digital clock. I made the worlds simplest mod ? to a small quartz analog travel clock to start when triggered. I use it to time how long it takes to discharge a battery to a specific voltage with a given load. The clock runs from a 1.5 volt AA cell. I stuffed a small strip of double sided pc board between the battery + and the contact in the battery compartment. The pc board sticks out of the back of the clock. A wire is soldered to each side of the PC board - when the wires are connected (by whatever - relay, switch, scr etc) the clock runs. By setting it at exactly 12:00:00 before starting, you have essentially a second counter that will last for 12 hours.

Like this:

-------------- || | AA }||{ < contact in clock battery compartment -------------- || || < double sided pc bo0ard +----||----+ | | | +---- < wires to +--------------- < switch/relay/etc

Electronic Goldmine has clocks like the one I used: item #G14709

Ed

I'm pretty sure the clocks at

will start counting up after they hit their target. I've got a Y2K clock from them kicking around somewhere, and I seem to remember this behavior. Check with them to be sure...

They start at $13 for the blank "make your own" clocks...

I was planning on using a digital clock, but will use analog if it's easier. I don't understand what exactly your device does.

I want to build an alarm clock that will trigger a stopwatch when it goes off. (Meaning, at 5AM, the buzzer will beep and start counting up.)

Say you set the alarm clock (any alarm clock) for 5:00 A.M. It goes off, at 5:00 A.M. Why do you need another clock/stopwatch/counter to count the seconds? The original alarm clock keeps running, so you can get the time directly from it.

That said, if you must have a second clock to count the time, what I posted originally does that. It does not start counting until it is triggered. Once triggered, it keeps on counting until the trigger is removed.

The alarm in the clocks in the link I posted is piezo. The signal that makes the piezo sound can turn a transistor or comparator on or off, and that can be used to control whatever you want to use as your counter, either directly or indirectly.

We need to understand what you are trying to accomplish. As pointed out, merely counting the seconds after an alarm clock rings is a function already available from the clock. We also need to know the anticipated duration. As mentioned in the previous post, a simple analog clock is good for only

12 hours.

Ed

There's plenty of Palm Pilot stuff that does that and more:

I am a high school student and need this for a science fair experiment.

I want to be able to record exactly how long it will take for the person to wake up. As soon as the buzzer wakes them up, they will press the button to stop the stopwatch.

So at a predetermined time at night (say, 5AM, or 2AM, or whatever), the buzzer will go off and a stopwatch will start counting up. As soon as the person wakes up, they will press a button to stop the counting-up. They will record whatever the stopwatch says on a sheet of paper. (Or, if possible, the time will be stored onto a memory chip.)

I need to make this device as dummy-proof as possible, so many students will participate in my experiment. It needs to be as cheap as possible to build and it needs to be very easy to use (All they have to do is press a button and the time shows up. They don't need to set anything, or do anything whatsoever.)

Ok - I can give you part of it. First, break it down into

3 pieces:

------- --------- --------- | Alarm | | Control | | Elapsed | | |========>| |======>| | | Clock | | Logic | | Timer | ------- --------- ---------

The alarm clock is a battery powered (*important* for safety) travel alarm clock you can buy. You can also buy the elapsed timer. See the web sites below for possible examples.

The control logic input is as follows:

+Vcc ---------------+--------+ | |k [Relay] [1N4001] | | +--------+ Alarm | Clock /c Piezo + ---[1K]----| NPN 2N3904 Buzzer \e | Ground

When the alarm rings, the relay will energize; when the alarm is turned off by the subject, the relay will de-energize. Ground connects to the negative side of the supply and the negative side of the battery in the clock.

If you use a clock/timer/stopwatch other than what I describe below (for example, one of those on the links I furnished above), then additional circuitry will be needed, and cannot be specified without knowing details about the device you choose.

If you use another battery powered travel clock like the ones at the Electronic Goldmine link I posted, then you can connect the relay operating point and normally open point to the double sided PC board I mentioned in an earlier post, ans slide that into the battery compartment of the elapsed time clock, between the battery + post and the contact in the battery compartment of the clock. That second clock will start running when the alarm rings, and stop running when the subject turns the alarm off.

You *will* need to ensure that the alarm is set before each test. Whether you let the total time accumulate on the elapsed timer, or record it each time (and reset the elapsed timer if you like) is up to how you want to perform the experiment.

The above approach is about the cheapest/easiest you can use for your experiment. You can go for a more high-tech looking project at increased cost/complexity. You can also go for a higher precision in counting the elapsed time, again at a higher cost/complexity. You'll need to consider your budget/skill/time available to decide which way to go.

Ed

If you're going to require your test subjects to read the stopwatch, why can't you just require them to read the time off the clock when they whap it? Set it for precisely 5:00.00, and if it takes it ten minutes to wake them up, the clock will say 5:10.00 or whatever.

Good Luck! Rich

Thanks. I asked the guy at Radio Shack, and he said that the hardest part would be finding the relay switch in the alarm clock (the thing that is triggered when the alarm reaches, say, 5AM). How can I find that?

Thanks. I asked the guy at Radio Shack, and he said that the hardest part would be finding the relay switch in the alarm clock. How can I find that?

Well, since you've neglected to copy/paste any context, I'm guessing as to what it is you're talking about here: it has something to do with triggering something when the alarm goes off. I did that once by hacking into the clock, and just picked off the pulse where it triggered the piezo, and fired a retriggerable one-shot with it. I didn't suppress the piezo sound, since it was for an actual alarm clock - the way I partied in those days, a wimpy little piezo on a clock radio wouldn't wake me up, so I built an oscillator - a couple of monostables, where one changed the frequency of another, so it went kinda "BRAAABRAWWWBRAAABRAWWWWBRAAABRAWWW" with an 8" 20-watt speaker.

Good Luck! Rich

How'd you pick off the pulse?

As for the context, it's earlier in this thread. I need to build an alarm clock that would also trigger a stopwatch. As soon as I hear the buzzer at 3AM, I would slam on the button to stop the stopwatch, and record the exact amount of time it took me to wake up.

Yes, but I'm using a real newsreader. It doesn't display whole threads like google does. All I see is the headers and the one message. When you learn to copy/paste, you save your readers the inconvenience of having to go track down what it is you're talking about.

Copying and pasting is really simple - move your mouse cursor to just before the first word of the thing you're answering, press the left mouse button, and drag the mouse to the end of the text you want to copy, highlighting it, and release the mouse button. Hit Control-C. That copies the highlighted text to your clipboard. Move the mouse cursor down to the google input box, position it appropriately, (preferably first thing), and hit Control-V to paste the clipboard. It's so simple, and effortless, and just imagine the number of people worldwide who might be more likely to want to participate if you did such a simple, courteous, considerate thing?

OK, find the transistor that drives the piezo, solder a .001 uF (1 nF) capacitor to its collector, condition the pulse, probably fire a non- retriggerable monostable, and start the stopwatch with it. Nothing to it! :-)

Have Fun! Rich

Yes, I know how to copy and paste.

OK, find the transistor that drives the piezo, solder a .001 uF (1 nF) capacitor to its collector, condition the pulse, probably fire a non- retriggerable monostable, and start the stopwatch with it. Nothing to it! :-)

I just went to Target and bought the cheapest alarm clock they had. It is a $5 alarm clock and has a radio, no buzzer. I can't find the transistor. (There's too many little things.)

Thanks, Jeff

I forgot to ask, what is a non-retriggerable monostable?

A lot of people might call that a crappy newsreader.

I don't understand why all these militant usenet crusaders are always whining at the google community because we don't clutter up the internet by sending the same text over and over and over every time we reply.

Usenet article headers contain all of the information your newsreader needs to follow the thread back to the original post. If your reader can't figure that out then you should be whining at the people that wrote it, or switching to a better one. I used to use pine about six years ago, and I am pretty sure it had no problem dealing with this. Heck, I think even netscape could do it back in the 90s.

I've used a bunch of software to browse usenet over the past 15 or so years, and I think google is just great because now I can see all of my threads no matter where I am, at a friend's house, on a library pc, or on any of the other pc's in my house.

But anyway, about the topic...

Alarm clocks are among the most obnoxious devices I've ever taken apart. They seem to do everything in the most complicated manner possible. I don't understand the rationale behind their design because it seems a $2 microcontroller, a crystal, and some LEDs would do what apparently takes a hundred or more components in a $9 alarm clock from Wal-Mart. It's almost as if they don't want you to reverse-engineer their product and discover the secret of counting to sixty.

So if you are up to the challenge, and have a little bit of time to work on it, you might consider building a clock from scratch. It's not very hard to do (or very expensive), and I happen to be developing a "build-your-own-alarm-clock" project for engineering students at my university. I'd be happy to send you a copy of the source code or even a few programmed chips. It wouldn't be very hard to tweak the programming to do what you want. In return maybe you and your teachers could write us a nice letter that we could show to the money people to prove that we're actually doing something.

You could even build an alarm clock that permanently stores a couple months worth of wake up time data and lets you read it back later; you could give out a handful of clocks, and the users could give them back to you to extract the information from. There'd be no need for them to remember to write down the times. Just email me if you're interested.

After you fire one , it finishes its cycle , before you can trigger it again.

Google choose to ignore general practice. Now you want the rest of the world to go along with that? If so ,expect to be ignored by lots of people,because I for one do not respond to a message without context.

You don't have to, just rectify the speaker output and use it to trigger your stopwatch.