I am guilty of leaving the iron on every now and then.
The worst was over the weekend after taking it to work on friday **
WARNING, YOU WILL BE WORKING WITH MAINS VOLTAGES!!!!
Follow at your OWN RISK.
I didn't need anything that fancy so just went with a dead man style system.
Hit the button to turn on and again every few minutes to keep the iron on.
I did want a buzzer on it but the lack of power supplied by the timer prevented this.
So if I was looking away and did not notice the flashing to indicate it was about to turn off, I would have to wait another minute for it to warm up from cold.
This turned out to be a good thing, as if I was looking away I was probably busy doing other things.
Good thing the iron heats up as quick as it does.
It has proved to be very useful.
ALso a good indicator how long a job actually takes.
I have set it up for 10 minutes.
Push the button to turn it on.
Flashes for 1 minute to indicate warm up.
Light goes solid.
At 9 minutes it starts flashing rapidly.
If the button is not pushed it turns off the iron.
How does it work?
With digital timers as cheap as they are now, $15, projects like this are a lot more affordable.
They come with a mains relay and rectified low voltage, suitable to drive a microprocessor.
My micro of choice is the ATMEL AVRs.
Coded with MCS's BASCOM AVR.
This particular specimen has a 48v relay.
Mains voltage is feed into a full wave bridge rectifier via a resistor.
A zener diode acts as the low voltage regulator.
A resistor divider drops it further down to the timer board's voltage.
I did not have to change much to get it working with the micro.
Change the resistor divider to bring the voltage from 1.2 to 5v.
Remove the backup battery.
To drive the relay, pull the transistor low.
Component count is pretty low on the new controller.
5 all up.
About $10 + cost of timer
Should have done it long ago.
The HPM timers from Bunnings are great.
Even less to mod.
As they use external user replacable batteries(2xAA) for the clock backup,
the low voltage is already dropped to 3.6v
Just add your own controller.
Bargin price to $13.
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Comment by kiwitrc, on 13-Oct-2009 05:24
Actually that looks to be a lot cheaper than having a wife to do the ironing.
Comment by nzsouthernman, on 13-Oct-2009 15:02
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