# Verifying my Zero Crossing detector & 230VAC switching circuit

#### Zen-

Joined May 25, 2014
14
These modules are low current and are tradionally used to plug in and populate/condition the 4 to 16 module I/O boards used with μp type I/O.
I am not sure if you can get the Opto22 where you are but there are equivalent stand alone units that go to 25amps.
You can get zero switching types.
Max.
The components are not dangerous. Apparently somebody is assuming you aren't able to assemble them correctly.
Well, of course the safer the better.

Would something like that http://www.ebay.com/itm/Solid-State...Electrical_Test_Equipment&hash=item53ef7abdd9
be safer to use?

And about the heating elements i know that i need to place them properly, fixed, and mounted with isolated material.

And i'm going to connect a fuse 1/2A (the current in the circuit is 0.2A) so in case that there would be any shortcut it won't catch on flames. (the electric board in the house has 16A limit as well)

Thanks.

Joined Jul 18, 2013
24,210
The ebay link shows a similar unit to the Opto22 unit I referred to.
You are using a heating device that is only 0.2A?
Max.

#### #12

Joined Nov 30, 2010
18,223
Repeating myself: The components are not, in and of themselves, dangerous.
They are used all over the world and are quite safe when used correctly.
However, you are betting an awful lot that you know all the requirements.
I know them. That's my day job. I'm not sure about you.
ps,
I didn't see where you said you were going to sell these hatcheries in several countries. For that, you would need an amazing array of, "Approvals".

Personally, I am much more afraid of the heaters which we did not discuss. Quite a few styles of heaters intentionally get hot enough to glow. You better know how to keep them safe or ASK! Redundant temperature limits, full metal shielding, fusible links, an alarm circuit to call a person to help if something goes wrong, etc.

I assume you are designing something that won't broil the livestock, but one layer of safety is not enough.

#### Zen-

Joined May 25, 2014
14
The ebay link shows a similar unit to the Opto22 unit I referred to.
You are using a heating device that is only 0.2A?
Max.
Repeating myself: The components are not, in and of themselves, dangerous.
They are used all over the world and are quite safe when used correctly.
However, you are betting an awful lot that you know all the requirements.
I know them. That's my day job. I'm not sure about you.
ps,
I didn't see where you said you were going to sell these hatcheries in several countries. For that, you would need an amazing array of, "Approvals".

Personally, I am much more afraid of the heaters which we did not discuss. Quite a few styles of heaters intentionally get hot enough to glow. You better know how to keep them safe or ASK! Redundant temperature limits, full metal shielding, fusible links, an alarm circuit to call a person to help if something goes wrong, etc.

I assume you are designing something that won't broil the livestock, but one layer of safety is not enough.

I'm not going to sell any to nobody, i just want to build one for my own use.

The heating elements are 6 resistors 200ohm 10W connected in series to 230VAC, that means aprox. 0.2A and aprox. 8W on each resistor, those are the maximum ratings.

As you have seen so far i don't have any problem with listening to you and your suggestions, in a matter of fact, i would be glad for any help/suggestion/advice from you.

If there is any component that will make this more safer just tell me, if you have any suggestion how to mount those resistors i would be glad.

Thank you!

#### #12

Joined Nov 30, 2010
18,223
The, "standard" is to use resistors rated for double the wattage the label says. It's about the difference between the rules the manufacturer plays by and the rules to build things that won't unsolder themselves.

Seriously. I've bought resistors that were hot enough to change a green circuit board into crispy brown if you believed the label. Apparently they wouldn't emit smoke or burst into flame at the "rated" wattage, so...I guess they passed some kind of "approval".

You'd be well advised to attach your resistors to a large piece of metal to spread out the heat (even if you buy 20 watt rated resistors). Cement style or aluminum cased? Maybe even a thin, closed, metal box? Lots of area makes heat soft.

and, no matter what kind of controller you design, at least add something like a Klixon brand high limit switch. You can get them anywhere from 0 F to something like 480 F.

http://airpax.sensata.com/tstat.html

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Joined Jul 18, 2013
24,210
What you also have to design for is the cold resistance, for Nichrome for e.g. cold, is 0.5/0.6 x the normal resistance when heated.
Max.

#### #12

Joined Nov 30, 2010
18,223
Hang on. Are nichrome resistors available?

#### Zen-

Joined May 25, 2014
14
The, "standard" is to use resistors rated for double the wattage the label says. It's about the difference between the rules the manufacturer plays by and the rules to build things that won't unsolder themselves.

Seriously. I've bought resistors that were hot enough to change a green circuit board into crispy brown if you believed the label. Apparently they wouldn't emit smoke or burst into flame at the "rated" wattage, so...I guess they passed some kind of "approval".

You'd be well advised to attach your resistors to a large piece of metal to spread out the heat (even if you buy 20 watt rated resistors). Cement style or aluminum cased? Maybe even a thin, closed, metal box? Lots of area makes heat soft.

and, no matter what kind of controller you design, at least add something like a Klixon brand high limit switch. You can get them anywhere from 0 F to something like 480 F.

http://airpax.sensata.com/tstat.html
So i can add some more resistors in series to lower the wattage, i purchased those resistors http://www.ebay.com/itm/390289106969?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

I thought about wrapping a thin metal around, and yes, bimetal thermostat will be connected.

#### #12

Joined Nov 30, 2010
18,223
Cement style. Square. I thought about making a metal plate across the bottom of the container with aluminum, .09 to .125 inch thick. Use transistor heat sink compound on the resistors and clamp them on. Either individual clamps or a second flat plate to make a sandwich. If there is no air communication, vapors can not get to the critters.

Don't, "wrap" them. They are already wrapped in cement and a metal wrapper makes it difficult to make safe connections.

Just suggestions...

Edit: If you're going to run these on a partial duty cycle, I guess you don't have to buy double wattage resistors. Besides, a metal heat spreader will falsify their ability (in a good way). If they only spend an hour or two per season at 100% power, they will last very well.

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#### Zen-

Joined May 25, 2014
14
Cement style. Square. I thought about making a metal plate across the bottom of the container with aluminum, .09 to .125 inch thick. Use transistor heat sink compound on the resistors and clamp them on. Either individual clamps or a second flat plate to make a sandwich. If there is no air communication, vapors can not get to the critters.

Don't, "wrap" them. They are already wrapped in cement and a metal wrapper makes it difficult to make safe connections.

Just suggestions...
Actually i am going to mount them to the ceiling and directly under them a 12V fan that will blow air at them, making air circulation.
I will attach their legs to not conducting board, wire wrap board would be okay?
and solder the legs, and the board will be connected with screws to the ceiling.

What is your suggestion about my question and suggestion about the number of those resisters that i should connect? i would still need about 25W or more.

Is there any way to calculate the temperature of the resistors in a particular current/wattage?

Thanks.

Edit: If you're going to run these on a partial duty cycle, I guess you don't have to buy double wattage resistors. Besides, a metal heat spreader will falsify their ability (in a good way). If they only spend an hour or two per season at 100% power, they will last very well.
Most of the time i would just need a little portion of wattage/heat from them, just to maintain the temperature.

#### #12

Joined Nov 30, 2010
18,223
I was thinking about the start-up each season. Starting from cold, your controller is going to throw them on at 100% power for a few hours. Still, mount them on some metal plate OR blow a fan on them, and you have no worries about them turning brown. I only wonder if the critters will find the draft annoying.

I'm sure there is a way to calculate the surface temperature of the resistors, but I don't think it's important enough to do the math. The answer will come out as, "degrees above ambient temperature". Suffice to say you won't enjoy touching them when they are running at full power, but modulated power and they will come down to, "not a hazard to exposed skin".

I don't know what wire wrap board is, but it's probably OK because it was designed for use in electronics.

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#### Zen-

Joined May 25, 2014
14
I was thinking about the start-up each season. Starting from cold, your controller is going to throw them on at 100% power for a few hours. Still, mount them on some metal plate OR blow a fan on them, and you have no worries about them turning brown. I only wonder if the critters will find the draft annoying.

I'm sure there is a way to calculate the surface temperature of the resistors, but I don't think it's important enough to do the math. The answer will come out as, "degrees above ambient temperature". Suffice to say you won't enjoy touching them when they are running at full power, but modulated power and they will come down to, "not a hazard to exposed skin".

I don't know what wire wrap board is, but it's probably OK because it was designed for use in electronics.

Thank you for all of your help and patience.

The incubator will be build from styrofoam, the dimensions would be something like an average table PC case, it should gain the required temperature quite fast, and there going be a fan that would work non stop to maintain the circulation of the air.
The embryos don't mind the flow of the air but the problem appears when the fan blowing directly towards the eggs causing the liquid inside them to vapor, other wise there is no problem with that, in a matter of fact, circulated air incubator are much more better then not circulated.

And this is a wire wrap board http://blog.imakecircuits.com/wp-content/uploads/2010/10/wire_wrap_8051_1.jpg

I think with 0.2A it won't do anything to the board, it's a common use board for electronic projects.

As i mentioned before, i will connect bimetal thermostat and i want to connect a fuse as well, which fuse do you recommend me regarding the max. current?

Thank you again!!!!!!

#### #12

Joined Nov 30, 2010
18,223
You're designing for .2 amps. You can get fuses at 1/4 amp or .312 amps, but be sure they are rated for 240 volts! My favorite source says you can't get a 240 volt fuse for less than 1 amp.

#### THE_RB

Joined Feb 11, 2008
5,438
Considering how much work you will have to do on the physical construction and insulating etc, I would just buy a PID temperature controller from ebay.

It will do everything you need, right out of the box for about $40. Then you can get down to tuning the PID and fixing all the heat flow problems with your enclosure. Thread Starter #### Zen- Joined May 25, 2014 14 You're designing for .2 amps. You can get fuses at 1/4 amp or .312 amps, but be sure they are rated for 240 volts! My favorite source says you can't get a 240 volt fuse for less than 1 amp. http://www.ebay.com/itm/10x-Glass-F...926?pt=LH_DefaultDomain_0&hash=item27b2ba1c46 Your source is wrong this time Considering how much work you will have to do on the physical construction and insulating etc, I would just buy a PID temperature controller from ebay. It will do everything you need, right out of the box for about$40. Then you can get down to tuning the PID and fixing all the heat flow problems with your enclosure.
Maybe you are right but the idea is me building it by myself (well, almost by my self).

I hope i will succeed with the project, if not it won't be to much disappointing, at least i tried.

#### BC107C

Joined Apr 3, 2011
14
From some experiments I did in the past, 60 to 80W of power is more than enough for a 1cu ft loosely insulated box.Another challange comes from the fact that you will need to open the box to rotate the eggs, and the heat and humidity will change.While the heat can quicly go back up to the set point, having the humidity controlled is tricky.
If a fan is installed, you will absolutely need a source of water to maintain the humidity.

#### #12

Joined Nov 30, 2010
18,223
If a fan is installed, you will absolutely need a source of water to maintain the humidity.
Good thing we have people like you. I have never even thought about the humidity of a chickens' butt.

#### Zen-

Joined May 25, 2014
14
From some experiments I did in the past, 60 to 80W of power is more than enough for a 1cu ft loosely insulated box.Another challange comes from the fact that you will need to open the box to rotate the eggs, and the heat and humidity will change.While the heat can quicly go back up to the set point, having the humidity controlled is tricky.
If a fan is installed, you will absolutely need a source of water to maintain the humidity.
Good thing we have people like you. I have never even thought about the humidity of a chickens' butt.
I'm not new in this thing, i am currently using an incubator genesis 1588 with automatic egg turner, i'm incubating eggs for several years.
The problem with this incubator is the temperature tuning with dip switches and it's just a head ache.

I will use the auto egg turner in the incubator that i am intending to build (hopefully), in addition if the Temperature control will work fine i will try to automate the humidity control too, the humidity accuracy isn't so important so it should be much easier to control it, for start i will put some sort of long container at one side and close a portion of the face area of the water/container to set roughly the humidity that needed.