Zero detect and sync to AC with P1?
Is there any chance this would have a value for fan speed control: Zero crossing detect opto triac driver ie MOC3041 and triac BTA40_600 and some other device to detect zero crossing. Have the Prop turn on a pattern of cycles for a pseudo PWM. 50% duty = 1 on then next off. 1 2 on then 3 off. 3 on 1 off. 3 on 2 off. etc. The point being to reduce noise by not turning on the triac at random places. If so what would a nice device be to look at the AC and fire a logic level output for the prop to lock to cycle by cycle.
https://www.onsemi.com/pub/Collateral/MOC3043M-D.pdf
https://www.onsemi.com/pub/Collateral/MOC3043M-D.pdf
Comments
How much amperage are you needing
The reason I am asking because there are readymade solutions that are out there can be interference with a micro controller board so if you are interested in something like this please let me know and I will post some web site links where you can find one
“ Zero crossing detect opto triac driver ” —>
( you would have to reverse engendering that portion of the circuit [ the part of the circuit that sense zero crossing to the micro controller portion of the circuit ] to understand how it is done )
You do need to tell me which amperage range you need they come in two flavors 40 amps and 100 amps ones
These readymade devices are used in battery spot welding machines ( these modules are easily modified-able
with a little bit of work ) [ these are transformer controllers or motor controllers { theses controllers do not work very well with incandescent light bulbs they flicker some what on low voltage level } ] you would also need to use the optic sensor
As you can see in the picture the portion that is on the high voltage side of the optic sensor is part of the controller board that you would want on your board that you would like to control ( one note this is the 100 amp version )
One other note on this particular module you might have noticed that it needs a 9 to 12 volt AC ( not DC voltage will not work correctly ) input this is for the micro controller circuit portion of controller [ but they are very hack able as well with a little bit of work ]
One final note there are versions of controllers out there that do not require a separate 9 to 12 volt transformer because it is incorporated on circuit board but this version is very limiting in its functionality ( for battery spot welding) but might be something to look at as well
Very soon I have a project thats what I might be doing because these control boards for battery spot welders are Smile the micro controller chips do not last very long and it is very seldom that the high voltage side of the circuit is the part that fails
The one good thing about these controllers is that they are not very expensive to buy I have bought several different versions of this type of controller board to try find one that would last but have not been very successful in doing this so far
I hope this helps you with what you are looking for
Built a circuit to do this many years ago using flipflops and a CD4017 to turn AC on/off for a number of cycles. Worked for 1/3, 1/2, 2/3 on/off cycles on my furnace fan.Should be simple to try it out now that we have sub $1.00 micros to control the triac.
PS For AC motors you must use full AC cycles. This (what I call AC cycle control) type of control works really well for maintaining temperature in ovens and larger chambers.
Could you please post some part numbers so I could look at the data sheet to see what the differences are
Thanks
Kwinn thanks for the part I’ll test those out. That is the idea. Although from your description it does not have a method to indicate the start of a rising voltage to make the start of a full cycle. it only shows Zero? But with code you could maybe get by just turning on a full cycle whether it starts out going low or high. Maybe a full cycle “is” just a full cycle for motor and heat purposes. Once you can control the triac at a cycle level you can the skip cycles. With split phase 240 the noise can be large when switching on mid cycle at peak.
The output from the zero crossing optoisolator will go low for each half cycle so you can use that to count down the on/off cycles. The on/off cycles would of course have to be multiples of two to have the on/off times be full ac cycles.
Sam thanks for the ideas. I have a prop board controlling lots of devices so I wont be looking at other devices to hack as you suggested. The circuit would look like an Opto device as Kwinn linked that would trigger on AC voltage and allow a logic level output that connects to the Prop. The code would look at the AC and when the voltage is at zero the Prop gets a pulse. On that pulse the Prop can count 2 more pulses from that one to determine that it has seen a full AC sine wave cycle. Understanding that the code can determine what a full cycle, it can then send a signal to an Opto Triac Driver ie MOC3041 which turns on a Triac at a simultaneous zero crossing. I suppose in a sense the Zero Crossing Triac Driver is a redundant to code watching for zero crossing, however it insures the effect of only turning on at zero volts. When the code and circuit can handle cycle by cycle management, my idea was to be able to have the code run a pattern to achieve reduced speed on a fan by skipping AC cycles as needed to achieve a desired lower speed. The circuit connected to the prop is very simple. The output of the Opto AC detect IC has a pullup resistor to 3v3 which is what the input to the Prop wants.
The circuit you've posted would probably be destroyed by an AC input. The reason is that the opto LED's reverse voltage max would be exceeded. To keep this from happening, you need to put a reverse diode across the the LED's inputs.
Also, it won't be triggered on a zero cross, but at whatever the LED's forward voltage is.
-Phil
If you don't care about isolation you can run the control circuit hot and do away with optos altogether, but this is only suitable for a fully sealed and simple circuit.
Interestingly here is an old thread on the same part connected to a prop with discussion by the usual suspects. I grabbed a screenshot from a circuit in that thread.
http://forums.parallax.com/discussion/107216/resistors-connected-to-h11aa1-getting-hot
Another circuit added.
Power companies do not like you using half cycles, so any control should always take care to switch pairs of half cycles to keep the load balanced.
Keep in mind power companies have an aversion to 'nasty loads' - anything other than an ideal sine load, causes more heating in their transformers.
As well as the balanced load requirements, you may come under the flicker specs too.
Google finds this comment around sub-mains frequency components
https://www.newtons4th.com/electromagnetic-compatibility-iec61000-3-32013-flicker-analysis/
" The graph below (taken from IEC61000-3-3:2013) illustrates the overall concept, we must remember that if the performance of the equipment under tests lies under the Pst = 1 curve then the disturbance to the supply network is deemed to be acceptable in the short term (we will distinguish between short term and long term later in this article)."
It's unlikely a crude mains cycle chopper would meet those specs for volume commercial production, but if it is one-off, you can experiment
Be aware that a simple resistor current limit can get quite hot and I would use 2W, not 1W for this on 240VAC. You can use the reactance of a capacitor plus resistor for this too. Another thing to be aware of is that you will get noise on the line that messes with the nice clean zero cross signal. There are various methods to deal with this but one of the things you can do is to maintain a phase timer so that you only accept a zero-cross signal within a certain window and if you didn't get that signal you would still trip on where it should have been anyway. When you do get a valid zero-cross you can resynch that phase timer which btw can be the same one used to measure phase delay.
Reliable Mains Zero Cross is a topic in itself, but you can use software to lower the BOM costs, and lower the power dissipation in the LED dropper
* Pick an opto coupler rated for lowest IF, to allow lower drive currents for lower power loss.
* If you measure edge plus period, you can SW correct for Opto CTR and mains voltage variation, and you can phase correct to the true zero cross.
* Dual LED opto couplers are more expensive (and lower CTR) than single LED ones, but single ones need a reverse diode.
Addit: A good example of a sensitive optocoupler is the TLP293(BLL, which specs 200~400% CTR band, at 500uA.
Is this the one that you had on your website years ago because I have a couple of them and I almost forgot about it
If is what you are talking about there some Basic Stamp code for this board
Moved to this post
Zero crossing detection for a battery spot welding machine with what parts should be used