Timer pulse

[timwarner]

I want to make my homeseer computer output a short electrical pulse (Between 3v & 15v for between 1 and 30 secs) to trigger the reset on a electronic timer I have.

I want to do it as cheap as possible if not free. Is there a way the do this with the parallel port?

It will be to keep tabs on the homeseer pc to make sure it has not crashed. If the timer times out because the pc has failed to reset it this would signal the pc has crashed and should be restarted.

[Waldoman]

I would think that a x10 relay modual N/O and a 9v battery would do it.

[zoomkat]

There is a parallel port plugin available tha might do the job. You can control the pins on the parallel port using simple bach files and such. cost probably depends on how you plan to interface with the external hardware and its setup. Could be as simple as a resistor, transistor, and some telephone wire.

[DC]

Or an X10 appliance module into which you plug an inexpensive transformer from Radio Shack (or similar). Connect the output (secondary) of the transformer to your electronic timer and plug the input (primary) into the appliance module.

[timwarner]

The parallel port plugin sounds good. I have got a homemade pcir that uses the parallel port. It there a way they could share the same port or would I need to add another port. Otherwise the idea of using a spare plug in module could work. I have some spare lamp modules I could use. Thankyou

[aboyce]

Looks good How are you setting it all up ?

[zoomkat]

The PCIR usually uses the first parallel port data pin. If you need other actions, just use the other 7 data pins to do those things.

[timwarner]

Thanks for everyones input on this one

Its good to know that I can use the both the pcir and the timer on one port.

In answer to Andrews question re. setting it up.

The timer is a very simple 555 timer that will be started on its countdown (15 minutes maybe) when the PC is turned on.

The circuit and the trigger taking power from the PC (game port maybe).

Every so often (maybe 3 minutes in this example) homeseer would send out a pulse (either the parallel port plugin or a X10 module). This pulse would be connected to the 555's reset pin and would start the countdown again.

If homeseer didn't send the pulses out then the timer would elaspe this would then either switch the power on and off (with a relay) or be wired in to short out the reset switch for a short time.

This is the basic idea it will need fine tuning but I will have a go and let you know how it goes.

[Microchip]

timwarner

Have just made the same thing.
You will have to refine it as you say with some logic. The main thing is to ensure that the timer is also reset when you reset the computer, otherwise you can end up with the timer holding the computer in the reset state!
I used 1/2 of a 556 as an oscillator of about 1 second pulse rate feeding a 4020 14 bit counter with reset. This is what the computer parallel port resets. You can choose the time required by selecting which output to use from the 4020. This then triggered a mono-stable, made from the other 1/2 of the 556, which pulsed a relay for 1 second. It also resets the counter.
To obtain a 15 minute delay with a 555 requires some low leakage capacitors otherwise the trigger voltage is not reached (there is a limit to the charging resistor as well).
You also need some means of switching off the reset to the computer in case you are using it for other uses and the HS program is not running.
I used the 12v from the computer as a power supply.
My system is running Win98 which means I can use the parallel port without problems. I also use it for control of other things and use D0 for IR control.

Good luck.

[timwarner]

Thanks Microchip I will have to look into your design. I have been a bit busy with my new daughter but I hope to get this working soon.

I will post any progress I have

Tim Warner