/diy/ - Do It Yourself

any ol' thermostat

when light is activated, the buzzer goes off until the capacitor is charged. It will take a fairly large cap I think.
time ~= .5 * buzzerResistance * capacitance
that's if the buzzer will still work at 1/2 voltage.
(I think, It's been a while)

I would just use an arduino but you could just use a relay in parallel with the light and a cheap door bell.

>>300282
improved - only one transformer

>>300282
improved - only 1 transformer

note: use a large value resister

>>300282
wow thanks for this, though I'm not really sure what I'm looking at, my electrical knowledge is pretty basic (see picture)
>>300284
like the picture?
>>300300 <-- very nice

third world general?

You could do this using a simple PTC resistor and a driver transistor.

>>300349
I cant open the pic, server problems

- when the thermostat first kicks on, the capacitor acts like a short, turning the buzzer on
- as the capacitor charges, the voltage across the buzzer goes down until it turns off.
the time it takes to drop to about 1/3 of the transformer voltage is (buzzerResistance * capacitance)

- when the thermostat kicks off, the capacitor is discharged through the resistor to get ready for the next cycle. since you have at least an hour or so before it needs to turn on again, use a very high value for the resister. 1M ohms or so.

Gut a cheap old toaster. It has all the parts to do this with except of course the light bulb.

I just noticed something...

This diode is needed to keep it from buzzing when the thermostat kicks off.
If that doesn't bother you, leave out the diode and resister (the capacitor will discharge through the buzzer and relay)

here is a simpler plan.

note that you must use an analog thermostat, coz the digital ones are made for 220volts, and also need a minimum load of about 200W. I see these old analog thermostats all the time at the thrift store for $2.

>>300358
uploaded the pic again, does it work now?
I'm not sure I can put together what is on your pic...

>>300370
this is much nicer, thanks anus presley!

though, what is that 1000uF at 16V

> what is that 1000uF at 16V

a capacitor. see http://www.radioshack.com/product/index.jsp?productId=12460840

this one is 25V not 16V, but that's fine. higher is better.

>>300372
Let me try to explain his pic.
A capacitor can be charged and discharged just like a akku. But with direct current they only can be charged. So at the beginning there flows current but later the capacitor has an infinity resistance. The time the capazitor has 66% of the whole tension is R*C. After this time the bell should stop ringing.

To discharge the capazitor you need to switch the polarisation. That is this switch for.

>>300382
I think I get it... But still, can the need for a capacitor be eliminated by using a buzzer with a single sound, not a continous which makes noise all the time it is getting power?

I guess that single sound kind of a buzzer would have a capacitor already built in?

Im just trying to do this with the least elements possible, and less elements there are, less possibilites for me to screw this up...

>>300384
Yes this is exactly the way a doorbell works.
Just tried to explain why it function this way.

>any ol' thermostat

If you are trying to measure the temperature of the hot water in your pipe, most off the shelf wall thermostats will not work. They are designed to measure air temperature and will be too slow to respond to low water temperature. You want something that tells you the pipes are cooling before the whole room cools.

You need a thermostat that measures the temperature of your water pipe. Danfoss, Honeywell, and others make products specifically for this task.

http://www.e-tradecounter.co.uk/p-544-clamp-on-mechanical-thermostat.aspx

These are normally meant to turn on water heater, but the contact can easily be used to turn on a lightbulb instead. This should give you an early warning that your water temperature is dropping.

They are very easy to install as well (just strap them onto an uninsulated portion of your hotwater pipe.

>>300395

And I know DIY loves to build everything from scratch, but for this simple a project just grab off the shelf parts for under $10 and be done with it.

Combination LED Warning light + buzzer (120V)

http://www.wolfautomation.com/products/30253/22mm-unibody-buzzer-with-ledbr24-or-110vacdc-ip20brchin
t-nfm1-22-series

Combine it with a cheap danfoss line voltage water pipe thermostat and you are done. The light will turn on and the buzzer will activate whenever the pipe temperature falls below your setpoint.

>>300397
buzzer not supposed to stay on

>>300370
don't think a thermostat will handle the current.
I could be wrong, it happened once before.

> don't think a thermostat will handle the current.

these are typically rated for 500 to 2000 watts, so I'm pretty sure they can handle a 60W bulb.

> don't think a thermostat will handle the current.

typical analog heating thermostats you find used for $2 are typically rated for 240V at 500 to 2000 Watts, so a 60W bulb is no sweat.

>>300440
Most thermostats have tiny wiring and low voltage.
2-8 amps? I don't think so Tim

This one is rated 24v with no mention of current.
http://www.homedepot.com/Building-Materials-Heating-Venting-Cooling-Thermostats-Programmable/h_d1/N-
5yc1vZbay9Z1z0xeug/R-100476730/h_d2/ProductDisplay?catalogId=10053&langId=-1&storeId=10051#s
pecifications

OP do this >>300361
use the buzzer values from this >>300370 (capacitor and buzzer) (increase the capacitor for longer time- I would start @ 2,200uF)
thermostat - kinda /diy/ but this guy might be right >>300395

12vdc transformer:
goodwill or whatever

diode:
>http://www.radioshack.com/product/index.jsp?productId=12673894&retainProdsInSession=1

spst relay:
>http://www.radioshack.com/product/index.jsp?productId=12477111&filterName=Type&filterVal
ue=SPST#tabsetBasic

>>300360
this

How about a box of marbles, a solenoid and a bell. When the light comes on a solenoid releases the marbles which drop onto the bell. When you add wood, simply refill the marble box.

>>300581
Well how about I take this http://www.ebay.co.uk/itm/Digital-Temperature-Regulator-Controller-Thermostat-LCD-220V-110V-12V-24V-
/200807377266?pt=LH_DefaultDomain_0&var=&hash=item2ec10d6972#ht_3077wt_902

a lightbuld and a ding dong doorbell...
the first ding is when the power is turned on
and the second ding when its turned off
(I need only the first ding, maybe there exists such a doorbell)

I know that actually these two parts contain all the capacitors and diodes and relays that you all listed for me...

but I'm kinda hung up on the simplest solution, regarding assembly.

though If I had the proper time, I'd be most pleased to make a nice wooden box to contain all the DIY wired up electronics, and integrated in the box a lightbulb,
and just hang this nice looking wooden box-contraption on the wall next to the radiator.

But as school starts in three days and there are a ton of other things that need to be done round the house and yard before the cold kicks in, I'd just like to get this thing operational and not spend too much time on it.
But I sure will screencap some posts and save them for the future if I'll ever make that wooden box thingy.

>>300608
I don't... I'm not... what?
I'm trying hard as it is that this will not come out like a contraption from tom&jerry.

>>300457

>Most thermostats have tiny wiring and low voltage.
>2-8 amps? I don't think so Tim

There are two types of thermostats commonly used in residential applications.

Class 2 (24v AC) powered by the 120v-24v transformer in a furnace. These thermostats can be bi-metal with anticipator, or digital with P+I logic and possibly a 7 day schedule. They are very limited when it comes to current capacity and they are also limited by the 40VA or 100VA furnace transformer that powers them.

The other common one is a line voltage bi-metal thermostat. These require no power to operate as they are all electromechanical. As they are just a normally open or normally closed contact their can handle a lot of current. 120V or 240v at 22A is not uncommon. These are commonly used for electric baseboard heaters, hot water radiators, gas fired unit heaters for workshops, and also for attic cooling fans.

Op is switching 120v so the line voltage stat is the obvious choice. They are also cheaper that most class 2 thermostats.