Hi, I post the scheme I've designed to realize a trailing edge dimmer, to drive dimmabel LED bulbs of my home. Unfortunately there isn't any shield available in the market made for this purposes and the triac leading edge dimmers don't produce good results with dimmable LED bulbs.
I hope the idea is interesting and somebody decide to produce it, I have several others to realize.
More infos here: A very efficent zero crossing dimmer (direct pin control from timer) - #8 by GiovanniG11
At least Krida Electronics is selling inexpensive trailing edge modules.
Thank you, I've found the module, it cost 25$ wich is not a lot but not also a few. It includes a dedicated microcontroller which measure analog input (can be from potentiometer, or from PWM source), and do the job itself
This has 2 negative reflections, the cost is more than simple hardware i desiged (wich actaully needs less components and connections) and it looses the educational purpose of drive manually the mosfets and give a full control of output.
The mosfets I used paralleled by diodes give chances to obtain more than 500W declared by Krida Electronics
Maybe because there is no demand for such a shield.
Maybe, but why they made shields for triac? Are today dimmers for incadescent bulbs needed more than LED bulbs? I dubt about that..
Triacs are suitable only for that, if it's about driving motors/heaters/etc it's suitable to buy chaper solid relays which turn on on the next zero crossing, no need for shields with triac.
By shield do you mean a board that you can plug on top of an Uno or Mega?
probably I didn't use the right word for that, but I wanted to give an idea fro the purpose to use it with Arduino.
Placing a 220V board on top of Arduino isn't a good idea for several reasons, and not ony safety ones. SO how to call it? Module?
Figuing out how ESP8266 managing the hardware pins driven directly by times give a chance to create cheap trailing edge dimmers working by WiFi. It's just necessary to manage the power part of scheme to power ESP too
Yes, so you may want to change your title to PCB or board or Module but not shield.
Triacs are commonly used in vacuum cleaners, washing machines, hair dryers, heating elements etc.
I agree $25 is high for that module, in Europe they sell it for 15.
I'm sure there's a market for that. I believe current designs are IGBT-based.
Like anything else of this nature - all it requires is thorough DVT and agency approvals.
In this case triacs are used as simple switch, starting with zero crossing, it's the same use of solid delay which are sold for few $. They have minus that they get hot and not power efficent like a pure contact.
A soft start of motor can be achieved as well with such switches, counting zeros and leaving only a few % of waves to energize motor, till 100%, in this case a board like this has sense, but it's not leading cut of waves.
You'll never see a motor driven by leading edge dimmer, if so, it's a mistake with different unpleasant results.
Leding edge triacs are concept of the past, a very cheap and simple way to dim the incandescent light, we need to look the future.
The thing I'll never see has a name:
"Universal Motor Speed Control"
To change the speed of an asynchronous motor you need to change frequency and voltage, there are devices called VFD for this.
Leading edge it's not a professional way, it's just a toy to use home to change (badly) the speed of your kitchen robot.. until the triac will collapse
Look, I agree there are technically better ways of controlling motor speed. But triac phase control is very common (because of cost) in commercial appliances, not something "I will never see".
I have at least 5 of them in my home and I don't even have a kitchen robot. My two vacuum cleaners have, my laundry machine has, also one fan and one infrared heater.
Have a look, what "toys" ST is making triacs for.
https://www.st.com/en/thyristors-scr-and-ac-switches/high-temperature-triacs.html
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