Circuit Design - Button activated timer with small "chirper"?

[HighFlight]

Hello all. I have a personal need for a small circuit. I have a good
understanding of components, how they are connected, and actually building
them, but an electrical engineer I am not. I was wondering if someone could
lend me a hand. It's probably very simple in design. Attached are my
requirements:

* Needs to be as small and light as possible.
* Attachable with Velcro. I'm imagining a PCB where the back has a stick on
Velcro pad.
* Small momentary button that when pressed, activates a 15 second timer
(approximately and no display needed). When the 15 seconds expires, a small
speaker should emit an audible chirping sound (audible from within
approximately 50-100 feet outdoors in a relatively quiet setting) at 5
second intervals. This chirping will continue until the button is pressed
again.
* There may be two buttons if size/weight/complexity is
smaller/lighter/simpler than required circuitry with single button.
* Replaceable battery (I'm imagining a watch size battery).
* Should be able to take a bit of bumping around. It is for a child's use
and will be attached to something that will undoubtedly be thrown or
dropped.
* Did I mention as light as possible???

I've bought from Allied et all in the past, so buying the speaker, buttons,
battery holder, etc. shouldn't be a problem. The physical layout and PCB
building should be something I can do. This is just a little project for my
son and me so I can just etch a board (hopefully one layer is enough). I
just have no idea what components to use.

Thanks very much for any assistance!

Jon

 

[D from BC]

[snip]

Small momentary button that when pressed, activates a 15 second timer
(approximately and no display needed). When the 15 seconds expires, a small
speaker should emit an audible chirping sound at 5
second intervals. This chirping will continue until the button is pressed
again.
Jon

...Just translating the logic.
1) If state change on button then start 15 sec delay and process next.
2) Start chirp procedure (An FM modulated square wave further
modulated by 5 sec blanks)
3) Exit procedure until state change on button
4) Wait for another state change to start (1)

Now the above might need some editing but it's a start and other
posters may make use of this for design ideas..

To me this is a microcontroller project

D from BC

 

[Rich Grise]

* Needs to be as small and light as possible. * Attachable with Velcro.
I'm imagining a PCB where the back has a stick on Velcro pad.
* Small momentary button that when pressed, activates a 15 second timer
(approximately and no display needed). When the 15 seconds expires, a
small speaker should emit an audible chirping sound (audible from within
approximately 50-100 feet outdoors in a relatively quiet setting) at 5
second intervals. This chirping will continue until the button is pressed
again.

You should look into the beeping softballs and stuff the they use for
blind pepole to play sports.

Good Luck!
Rich

 

[D from BC]

3) Exit procedure until state change on button

Ooopss...Correction to step 3
3) Exit procedure if state change on button..

D from BC

 

[DaveM]

Hello all. I have a personal need for a small circuit. I have a good
understanding of components, how they are connected, and actually building
them, but an electrical engineer I am not. I was wondering if someone could
lend me a hand. It's probably very simple in design. Attached are my
requirements:

* Needs to be as small and light as possible.
* Attachable with Velcro. I'm imagining a PCB where the back has a stick on
Velcro pad.
* Small momentary button that when pressed, activates a 15 second timer
(approximately and no display needed). When the 15 seconds expires, a small
speaker should emit an audible chirping sound (audible from within
approximately 50-100 feet outdoors in a relatively quiet setting) at 5 second
intervals. This chirping will continue until the button is pressed again.
* There may be two buttons if size/weight/complexity is
smaller/lighter/simpler than required circuitry with single button.
* Replaceable battery (I'm imagining a watch size battery).
* Should be able to take a bit of bumping around. It is for a child's use and
will be attached to something that will undoubtedly be thrown or dropped.
* Did I mention as light as possible???

I've bought from Allied et all in the past, so buying the speaker, buttons,
battery holder, etc. shouldn't be a problem. The physical layout and PCB
building should be something I can do. This is just a little project for my
son and me so I can just etch a board (hopefully one layer is enough). I just
have no idea what components to use.

Thanks very much for any assistance!

Jon

Unless I'm very confused, sound level from a watch-sized battery powered audio
transducer is going to be very faint at 100' outdoors, even if it's quiet. I
think you're going to have to look at something a bit more powerful.
As another poster said, seems a natural for a uP project, except for the audio
part.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Some days you're the dog, some days the hydrant.

 

[ehsjr]

Hello all. I have a personal need for a small circuit. I have a good
understanding of components, how they are connected, and actually building
them, but an electrical engineer I am not. I was wondering if someone could
lend me a hand. It's probably very simple in design. Attached are my
requirements:

* Needs to be as small and light as possible.
* Attachable with Velcro. I'm imagining a PCB where the back has a stick on
Velcro pad.
* Small momentary button that when pressed, activates a 15 second timer
(approximately and no display needed). When the 15 seconds expires, a small
speaker should emit an audible chirping sound (audible from within
approximately 50-100 feet outdoors in a relatively quiet setting) at 5
second intervals. This chirping will continue until the button is pressed
again.
* There may be two buttons if size/weight/complexity is
smaller/lighter/simpler than required circuitry with single button.
* Replaceable battery (I'm imagining a watch size battery).
* Should be able to take a bit of bumping around. It is for a child's use
and will be attached to something that will undoubtedly be thrown or
dropped.
* Did I mention as light as possible???

I've bought from Allied et all in the past, so buying the speaker, buttons,
battery holder, etc. shouldn't be a problem. The physical layout and PCB
building should be something I can do. This is just a little project for my
son and me so I can just etch a board (hopefully one layer is enough). I
just have no idea what components to use.

Thanks very much for any assistance!

Jon

The light weight requirement and 50-100' range is gonna
kill your battery life. I think the first thing you need
to do is find a sounder thatmeets your requirement for
audibility at the range you want, and then design from
there. The louder it needs to be, the more power it
will take from the battery. I think a Sonalert may give
you the best audibility vs power.

I'll ignore battery life for the following conceptual
level circuit. (You can Google for 555 circuits) It
requires 2 555's and a 4017, 2 mosfets and an SCR,
plus support components:

-----
/ | 555 |
Gnd ---o o---2| 15 |---A
Switch | secs|
-----

The 555 is configuired as a monostable.
Each press of the switch creates a + pulse
at point A for 15 seconds.

+----------+
| d|_
| | | P channel Mosfet
| |<| |
| s+-| |g___ to point B on 4017
| |
--- ------
A-+---|SCR| | 555 |
| --- | 5 |-----+
| | | secs | |
| | ------ |
| | | _|d
| +----------+ | | P channel mosfet
| | | |>|
+-->|-------+-----+___| |-|s
D1 | | |
| | |
| [1K] [Sounder]
| | |
Gnd ----+-----+-------------+

The 15 second pulse at point a is connected to the
gate of an SCR, which turns the SCR on, as long
as Q1 conducts. Q1 conducts while B is negative
(more on this later). That allows the 5 second 555
astable to run.

So, up to this point: 1 press of the button triggers
the 15 second time to run for 1 cycle, then stop.
That timer turns on an SCR, which will stay on as
long as current is drawn through it. Current is drawn
by the 5 second timer through Q1, so the SCR stays
on and the 5 second stable will keep running until
Q1 is turned off.

The output of the 555 astable feeds the sounder through
Q2. Q2 is held off during the 15 seconds that point A is
plus. Therefore, the circuit will not start sounding
during the 15 second cycle. After that, it will sound
every 5 seconds.

Now, all we need to do is control point B to be negative
until the second press of the switch. You can use a
flip flop or a counter to do that. I'll discuss using
a 4017 counter:
-----
A----|14 |
| 2|---B
| |
| 4|--+
| | |
| 15|--+
-----
4017

The clock signal comes in on pin 14, which is
connected to the output (point A) on the 15 second
timer. Each press of the switch triggers the 15
second timer. Each clock pulse advances the
4017 count by 1, until the 4017 is reset, at which
time the count returns to 0. As configured,
count 2 (pin 4) is connected to the reset pin
on the counter (pin 15). Therefore the counter
can only count 0,1,0,1,0,1 etc. That means that each
press of the switch changes the polarity on pin 2
(point B) from + to - or - to +

Ed

 

[HighFlight]

That was an awesome reply. Electronics has always intrigued me (that's why
I'm trying to expose my son to it). I've just never had the ability to "get
it" at the level making even simple circuits like this one. I'm sure it
took you longer to describe it and it did for your to craft it.

Everyone's point about the volume and battery life was already in the back
of my mind. But I'll start by shooting for the stars and I'm sure be more
than happy with a middle ground. I'm sure that 50', if attainable, would be
sufficient.

Thanks very much. I'll reply back if I have any follow-up questions. But
your response was excellent. I greatly appreciate you taking the time to
write it.

Jon

Thanks very much for the reply. I'll run with that and do some reading on
the components and play around with some sizing estimates.

Hello all. I have a personal need for a small circuit. I have a good
understanding of components, how they are connected, and actually
building them, but an electrical engineer I am not. I was wondering if
someone could lend me a hand. It's probably very simple in design.
Attached are my requirements:

* Needs to be as small and light as possible.
* Attachable with Velcro. I'm imagining a PCB where the back has a stick
on Velcro pad.
* Small momentary button that when pressed, activates a 15 second timer
(approximately and no display needed). When the 15 seconds expires, a
small speaker should emit an audible chirping sound (audible from within
approximately 50-100 feet outdoors in a relatively quiet setting) at 5
second intervals. This chirping will continue until the button is
pressed again.
* There may be two buttons if size/weight/complexity is
smaller/lighter/simpler than required circuitry with single button.
* Replaceable battery (I'm imagining a watch size battery).
* Should be able to take a bit of bumping around. It is for a child's
use and will be attached to something that will undoubtedly be thrown or
dropped.
* Did I mention as light as possible???

I've bought from Allied et all in the past, so buying the speaker,
buttons, battery holder, etc. shouldn't be a problem. The physical
layout and PCB building should be something I can do. This is just a
little project for my son and me so I can just etch a board (hopefully
one layer is enough). I just have no idea what components to use.

Thanks very much for any assistance!

Jon

The light weight requirement and 50-100' range is gonna
kill your battery life. I think the first thing you need
to do is find a sounder thatmeets your requirement for
audibility at the range you want, and then design from
there. The louder it needs to be, the more power it
will take from the battery. I think a Sonalert may give
you the best audibility vs power.

I'll ignore battery life for the following conceptual
level circuit. (You can Google for 555 circuits) It
requires 2 555's and a 4017, 2 mosfets and an SCR,
plus support components:

-----
/ | 555 |
Gnd ---o o---2| 15 |---A
Switch | secs|
-----

The 555 is configuired as a monostable.
Each press of the switch creates a + pulse
at point A for 15 seconds.

+----------+
| d|_
| | | P channel Mosfet
| |<| |
| s+-| |g___ to point B on 4017
| |
--- ------
A-+---|SCR| | 555 |
| --- | 5 |-----+
| | | secs | |
| | ------ |
| | | _|d
| +----------+ | | P channel mosfet
| | | |>|
+-->|-------+-----+___| |-|s
D1 | | |
| | |
| [1K] [Sounder]
| | |
Gnd ----+-----+-------------+

The 15 second pulse at point a is connected to the
gate of an SCR, which turns the SCR on, as long
as Q1 conducts. Q1 conducts while B is negative
(more on this later). That allows the 5 second 555
astable to run.

So, up to this point: 1 press of the button triggers
the 15 second time to run for 1 cycle, then stop.
That timer turns on an SCR, which will stay on as
long as current is drawn through it. Current is drawn
by the 5 second timer through Q1, so the SCR stays
on and the 5 second stable will keep running until
Q1 is turned off.

The output of the 555 astable feeds the sounder through
Q2. Q2 is held off during the 15 seconds that point A is
plus. Therefore, the circuit will not start sounding
during the 15 second cycle. After that, it will sound
every 5 seconds.

Now, all we need to do is control point B to be negative
until the second press of the switch. You can use a
flip flop or a counter to do that. I'll discuss using
a 4017 counter:
-----
A----|14 |
| 2|---B
| |
| 4|--+
| | |
| 15|--+
-----
4017

The clock signal comes in on pin 14, which is
connected to the output (point A) on the 15 second
timer. Each press of the switch triggers the 15
second timer. Each clock pulse advances the
4017 count by 1, until the 4017 is reset, at which
time the count returns to 0. As configured,
count 2 (pin 4) is connected to the reset pin
on the counter (pin 15). Therefore the counter
can only count 0,1,0,1,0,1 etc. That means that each
press of the switch changes the polarity on pin 2
(point B) from + to - or - to +

Ed

 

[neon]

wow first thing you know you will end up with the kitchen sink. use LM555 timers cheap easy to use gabz of info available on the internet use one as oneshot the get the delay for your time required then use another to free oscillate at frequency that bothers you this guy can drive a 100 ohm speaker crazy small size 1"x 1" layout a 9 volts battery will last for maybe 1 hour before it dies.if you want loud and beep beep then maybe a sonalert is better as an output as opposed toa speaker. loud enough for 300meters and 95 DB.