timer circuit

[Jeff Broner]

I don't know anything about electronics, but I'm willing to learn if this
project is possible: I'd like to build a very compact timer that runs on AC
115v 60hz. It would consist of a simple clock circuit that outputs to some
kind of programmable logic circuit. This circuit would be programmed to turn
a relay on/off at specific times of the day (it could be a one time
programmable type of thing). My ideal design would be all solid state and
fairly compact, like less that 1.5" (~ 40 mm) cube. What I'd basically be
making is a lamp timer like the ones you can find at walmart, but much
smaller and minus the digital interface. Is this possible, and if so how
cheap could it be made? Any suggestions on manufacturers of the components?
Thanks.

 

[Graham W]

"Jeff Broner" <toplite@nospam.com> wrote in message
news:BX1Mc.7811$_K2.614@lakeread02...

I don't know anything about electronics, but I'm willing to learn if
this
project is possible: I'd like to build a very compact timer that runs on
AC
115v 60hz. It would consist of a simple clock circuit that outputs to
some
kind of programmable logic circuit. This circuit would be programmed to
turn
a relay on/off at specific times of the day (it could be a one time
programmable type of thing). My ideal design would be all solid state
and
fairly compact, like less that 1.5" (~ 40 mm) cube. What I'd basically
be
making is a lamp timer like the ones you can find at walmart, but much
smaller and minus the digital interface. Is this possible, and if so how
cheap could it be made? Any suggestions on manufacturers of the
components?

If you don't know anything about electronics then you shouldn't be
starting on AC mains powered projects. Not only will you likely destroy
the components from high voltage static but also yourself by getting
stuck across the AC.


--
Graham W http://www.gcw.org.uk/ PGM-FI page updated, Graphics Tutorial
WIMBORNE http://www.wessex-astro-society.freeserve.co.uk/ Wessex
Dorset UK Astro Society's Web pages, Info, Meeting Dates, Sites & Maps
Change 'news' to 'sewn' in my Reply address to avoid my spam filter.

 

[Watson A.Name - \"Watt Su]

"Graham W" <graham@his.com.puter.INVALID> wrote in message
news:410113bd$0$96021$ed2619ec@ptn-nntp-reader03.plus.net...

"Jeff Broner" <toplite@nospam.com> wrote in message
news:BX1Mc.7811$_K2.614@lakeread02...
I don't know anything about electronics, but I'm willing to learn if
this
project is possible: I'd like to build a very compact timer that
runs on
AC
115v 60hz. It would consist of a simple clock circuit that outputs
to
some
kind of programmable logic circuit. This circuit would be programmed
to
turn
a relay on/off at specific times of the day (it could be a one time
programmable type of thing). My ideal design would be all solid
state
and
fairly compact, like less that 1.5" (~ 40 mm) cube. What I'd
basically
be
making is a lamp timer like the ones you can find at walmart, but
much
smaller and minus the digital interface. Is this possible, and if so
how
cheap could it be made? Any suggestions on manufacturers of the
components?

If you don't know anything about electronics then you shouldn't be
starting on AC mains powered projects. Not only will you likely
destroy
the components from high voltage static but also yourself by getting
stuck across the AC.

Not to mention burning the house down.

--
Graham W

 

[Byron A Jeff]

In article <BX1Mc.7811$_K2.614@lakeread02>,
Jeff Broner <toplite@nospam.com> wrote:

I don't know anything about electronics, but I'm willing to learn if this
project is possible:

It's possible. Though it's doubtful that you'll be able to build a one off
for less that it takes to buy one.

I'd like to build a very compact timer that runs on AC
115v 60hz. It would consist of a simple clock circuit that outputs to some
kind of programmable logic circuit. This circuit would be programmed to turn
a relay on/off at specific times of the day (it could be a one time
programmable type of thing).

It can be done. In fact there are a variety of ways to do it. I'll throw out
one approach.

My ideal design would be all solid state and
fairly compact, like less that 1.5" (~ 40 mm) cube. What I'd basically be
making is a lamp timer like the ones you can find at walmart, but much
smaller and minus the digital interface. Is this possible, and if so how
cheap could it be made? Any suggestions on manufacturers of the components?

Since it's line powered you can use the accuracy of the sine wave through the
line to provide the clock base. The circuit here provides an example:

http://www.play-hookey.com/digital/experiments/line_clock.html

You only need the top resistor/zener circuit. The bottom one is redundant.

The key component is the transformer. It serves a few purposes:

1) It lowers the voltage from unsafe 120V levels to safer sub 20V levels.
2) It isolates your circuit from line power.
3) It will provide power for your circuit. Check out the power supply for
logic circuits link on the above page. A single transformer can give power and
provide the time base too. An ideal transformer will output 9V AC.

Now the output of the given circuit will give you 60 ticks per second. This
is where the paths diverge for most project. Many will suggest using discrete
counters (like the 7490) to divide down the ticks into something reasonable.
To count a minute you need a counter that will change once every 3600 ticks.

This is the point that I advocate using a microcontroller. A part such as the
PIC 12F629 or a 16F630 cost less than $2 and can track the time and drive the
relay.

You need a programming language to do this. While normally I suggest using
PIC assembly, for simple projects may something like JAL (http://jal.sf.net)
may be appropriate.

Good luck in your project.

BAJ

 

[Gary Lee Calvert]

suggest you search ebay for X 10 under consumer electronics...
I have several of these items running in my house. Good luck


"Jeff Broner" <toplite@nospam.com> wrote in message
news:BX1Mc.7811$_K2.614@lakeread02...

I don't know anything about electronics, but I'm willing to learn if this
project is possible: I'd like to build a very compact timer that runs on
AC
115v 60hz. It would consist of a simple clock circuit that outputs to some
kind of programmable logic circuit. This circuit would be programmed to
turn
a relay on/off at specific times of the day (it could be a one time
programmable type of thing). My ideal design would be all solid state and
fairly compact, like less that 1.5" (~ 40 mm) cube. What I'd basically be
making is a lamp timer like the ones you can find at walmart, but much
smaller and minus the digital interface. Is this possible, and if so how
cheap could it be made? Any suggestions on manufacturers of the
components?
Thanks.