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Relays, mains fail, delay.
- Thread starter Lectrician
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hmmm - I think it must have been a case of the "saved draft genie", or somesuch striking again. I must have clicked something wrong 'cos the message I had posted about an hour
Kind Regards, John
Edit: typo corrected
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Extremely good point
Not only did I allow myself to be distracted by MikeOfLondon, and then bernard, introducing the concept of relays, but I'd overlooked the fact that it's something I've not infrequently done, myself, without any relays.Indeed, as I have also have a number of examples of in my house, depending on the signal requirements (and input impedance) of what is being triggered, one doesn't necessarily even need a transistor - some of my such systems using nothing more than one diode and one (small) capacitor (for example, one which triggers an alarm after about 10 mins of sustained loss of power to a particular piece of equipment).
If one wants/needs to invert the signal, then one obviously does need a transistor - but the power requirements of that for a modest period of time such as being discussed (and quite a long way beyond) can, again, be served by a very modest capacitor. Indeed, again, those power requirements will be extremely small if a load with a high input impedance is fed by the signal. There would be a potential problem if one required a sustained inverted output, maybe for hours/days, in the absence of power - and that would usually require a battery of some sort.
Kind Regards, John
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Can't believe you get thanks for that cocky, un-helpful post.
I thanked him before it was helpful, and because of my embarrassment at having let myself be distracted by all this talk of (current hungry) relays
Do you know the input impedance of your text dialler? If it's high, then you may need no more than a diode and modest capacitor (and a tiny ELV-output transformer of some sort {edit: and a second diode}) to get your off-delay.
Kind Regards, John
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@JohnW2 that's OK. I inserted a comma between "posted" and "about" and it read just fine
One more crazy idea. A loop of copper pipe filled with glycol/water solution and heated by an element. A pipe thermostat opens and closes when the water is hot/cold enough and acts as the time delay mechanism. Another pipe thermostat acts as an overheat stat for the element.
One more crazy idea. A loop of copper pipe filled with glycol/water solution and heated by an element. A pipe thermostat opens and closes when the water is hot/cold enough and acts as the time delay mechanism. Another pipe thermostat acts as an overheat stat for the element.
@JohnW2 that's OK. I inserted a comma between "posted" and "about" and it read just fine
Why a loop of pipe, and why the glycol? It might be difficult to get a time delay anything like as short as 30 seconds with that method!
In fact, anything kept heated to above ambient temp by the power until it goes off could be used to trigger a thermostat when the 'anything' cools down at some time interval after the power disappears.
Kind Regards, John
can you still get pneumatic delayed contractors? Not seen one for a while.
If you really want a silly idea then I am in for it. Wait till you see my contraption.
uses no back up power, will send text after a time delay and will send a delayed message after power restore. I will do a little sketches on paint. wait for it, I am very very busy but I got to stop doing everything else and do this as I enjoy fun things much more than earning £50 an hour.
uses no back up power, will send text after a time delay and will send a delayed message after power restore. I will do a little sketches on paint. wait for it, I am very very busy but I got to stop doing everything else and do this as I enjoy fun things much more than earning £50 an hour.
Photobucket is down, waiting to load my silliest mains fail timer circuit which does not use back up electric power but does use something else which is top secret for now.
It is expected to consume around 10watts of electrical power.
It is expected to consume around 10watts of electrical power.
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who is Robinson Heath?Ah. Do I take it that you're related to Heath Robinson?
Kind Regards, John
edit my bad! Oh that eccentric cartoonist! I am sure we are all sharing a strand of his DNA.
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In what sense is it unhelpful?
Do you need me to explain why a solution using transistors would be superior?
As for cocky, I've no idea what you're talking about.
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