Heater Electronic Thermostat

[SiriBrazil]

Hi, friends! I intend to build a simplest 110 VAC electronic controlated heater to use in my aquarium. I would like do make it at the most simple (and sheap) possible, therin a opted to use a thermistor as themosensor and SCR and Triac as charge switches, and wich control circuit could work not using DC Power but directly AC power. Can someone help me? Thanks a lot. (P.S.: I ask you to excuse my "not so good' English, I'm braziliam...)

 

[Sceadwian]

It would be cheaper to purchase one at a store than it would be to build one, and it is not a good learning excercise for electronics.

 

[HarveyH42]

High voltage and water don't mix well. This is something best left to a store bought unit. Since you are asking for help, I'm presuming you don't have the knowledge to keep the water away from the electronics. I hate getting shocked, so mostly work in DC. Really dread working on stuff plugged into the wall. Good luck, and be careful.

 

[3v0]

A GFI (Ground Fault Interrupt) is a must for all aquarium equipment scratch built or purchased.

I agree with the above posters.
Since you intend to duplicate what you can already buy then just buy it.

 

[Sceadwian]

I just got a casual shock from 110 yesterday, and that was from dry skin contact. I spent 5 minutes swearing I'd never go near line voltage again. After that 5 minutes it faded but you get my meaning =)

 

[ericgibbs]

hi siri,

Buy a ready made/shop water heater.

The design and construction of a home made heater wouldn't be the problem.

The problems/risks start when you try to ensure safety against electrical hazards, today and long term.

Have you got all the equipment required to carry out the necessary insulation testing.

Will the materials you using for sealing, for example, be adequate.etc

Also follow 3v0's advice, always fit a RCCB, especially where water or outdoor electrics are concerned.

I know that we must appear downbeat, but you did ask for our experienced advice

Eric

 

[3v0]

If I were to build an aquarium heater system I would start with off the shelf heaters. Use 2 small ones per tank. That way if one fails you sill have the other. Set the temperature setting to just above what you will need.

Then I would build a controller that would read the tank temperature with at least 2 probes. Redundancy is a good thing. I would use relays to turn then heater(s) on as needed.

You could write code that would do daily or season temperature cycles as required by the fish. Maybe a button on the controller that would generate the temperature profile that would cause the fish to mate.

Use a RS232 or USB port to download temperature profiles to the controller.

Add an addition relay to control the lights. Add a sensor to ensure the air pumps and filters are working.

Add a 4 line LCD display to show the current temp, Max and Min for the last 24 hours. Other info as needed

Add an audible alarm to signal problems. Have the controller call you cell phone if things went south.

What you can do is nearly endless. What you suggest is not worth the effort.

 

[Hero999]

Use a small linear poer supply as the DC source of this circuit.

 

[SiriBrazil]

Thank you all, guys, for your answering and worrying. I'm even that water and high voltage is not a good combination to play with, and I promise I will be careful with this. But, once dealing about sink heater, it's unavoideble... I know too so that using DC, and rellays as switch, it is more simple, safe and apropriated (and was already decided for this way) but, quite so, my problem (doubt) still stays: how to make a thermostat, that uses a thermistor as a sensor, work directly in a 110 VAC, without a properly DC power source device?

Thank you too, Mr. 3vO, for your detaileds and finest concernings, but I'm afraid that they could be a bit expensive to me now (by the way, I did not undestand very well , I'm sorry, what means your last paragraph.

Tank you too, Mr. Ericgibs, I have a basic sink heater already, and all wat I dream with is to adapt in it a thermostat, and this thermostat should work in order to turn the heater charge off when certain temperature was detected inside the tank. And it is irrelevant to me if the thermostat works on or off board, since works. And be sure you are not downbeating me, but instead encouraging.

Anyway, I'm gratefull for you all for your contribution. I apreciated and wil analyse the sugestions (and I hope you, Sceadwian, were better (or more serene, at least...) now, from the shock you got). Forgive me if being boring.

Best Regards

SiriBrazil

 

[Hero999]

You can use a transformerless power supply but it probably won't be able to supply enough current for the relay coil in my circuit but I'd recommend using a small transformer rectifier and capacitor.
**broken link removed**

 

[3v0]

SiriBrazil,

I would be happy to answer any questions.

 

[SiriBrazil]

0k, Hero999,

Thank you for your atemption. I will consider your sugestion. I was trying to avoid DC power suply, but it seam more dificult than I thougth.

Thanks again.

SiriBrazil

 

[Carz]

phone call

3v0,

How would you make a this call your cell phone? If it did call your phone would it give you a series of tones to indicate a problem?

Thanks in advance,
Carz

 

[3v0]

3v0,

How would you make a this call your cell phone? If it did call your phone would it give you a series of tones to indicate a problem?

Thanks in advance,
Carz

It is easy to have a microprocessor dial a phone number. You can do it with a simple relay or DTMF.

Once the connection is made you have several options.

Beep out some code that is meaningful to you.
Record some low quality speech (1 or 2 bit) and have the PIC send it over the phone when needed. Roman Black PicSound
Have the controller signal a Windows XP PC and have it speak the needed message. How To Configure and Use Text-to-Speech in Windows XP