How can I control two AC fan (220VAC) using pic microcontroller without external PS?

[Mithun_K_Das]

How can I control two AC fan (220VAC50Hz) using pic microcontroller without external PS? I mean I don't wanna use any transformer to drive the circuit. Also the circuit must be small.

Need ideas.

 

[FoxyRick]

How small???

Search for "transformerless power supply". Try this to get you started:

https://electroschematics.com/3752/transformer-less-power-supply/

Even better, this:

https://www.picbasic.co.uk/forum/showthread.php?t=12249&p=81417#post81417

 

[Genovator]

You have to use triac.
Refer to this. It might help you...

https://www.8051projects.net/lofiversion/t23601/fan-220v-ac-speed-control.html

 

[Mithun_K_Das]

I was actually looking how to control the AC fan (85W,220VAC,50Hz) with microcontroller. And I want to keep the circuit free from isolation. That means I don't wanna use opto-coupler. I want to use the microcontroller with the same ground of the AC supply so that direct micro-controller can drive the TRIAC without any opto-coupler. And the micro-controller will trigger with the zero-crossing point(depending on regulator position).

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Genovator, your link is ok. I want to build something like that. But Here they have used an external power supply and MOC3021 is used to keep an isolation between TRIAC and micro-controller. But what I really wanna do is to avoid these extra circuits. I want to use the microcontroller without any opto-coupler and external power supply.

 

[FoxyRick]

So take the optoisolator out of the circuit and use a similar power method to what I gave links for.

STMicro has triacs (e.g. BTA16-600SW) that are intended for direct drive from logic.

Why the aversion to an optoisolator?

It helps to specify exactly what you want in the first post.

 

[Mithun_K_Das]

I want to keep the circuit small and also cost effective. because it will be used for a very small load(<60W) and need to fix within a tiny space. Thats why I don't want to use opto-coupler.

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A small product named fan regulator can do this easily. But I want to make it with micro-controller. SO that I can add other features as my choice (such as timer, temperature controlled etc.)

 

[arianofiran]

I want to keep the circuit small and also cost effective. because it will be used for a very small load(<60W) and need to fix within a tiny space. Thats why I don't want to use opto-coupler.

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A small product named fan regulator can do this easily. But I want to make it with micro-controller. SO that I can add other features as my choice (such as timer, temperature controlled etc.)

just check this:
ww1.microchip.com/downloads/en/AppNotes/00954A.pdf

 

[KhaledOsmani]

Open relay switch:

 

[D.A.(Tony)Stewart]

Mithun_K_Das said " I was actually looking how to control the AC fan (85W,220VAC,50Hz) with microcontroller. And I want to keep the circuit free from isolation. That means I don't wanna use opto-coupler.

If you intend to use for yourself only, OK but safety regulations require isolation because some homes are miswired with reverse Hot Neutral. Using a polarized 3 pin plug, the neutral can be up to 2% of the line voltage at max household load current. It is only grounded at the pole transformer, some may have copper in the ground near the home.

With that in mind, if you connected neutral to ground at home, you create an "unsafe ground" network, exposed to lightning transients on the neutral, ground faults etc..

However if Neutral is close to ground, they only required 2 diode drops to trigger at low current , somewhat like TTL threshold at 1.3V. Of course if power transients arc on your board then the PIC may get fried and any user connected near the switch.. So in an controlled environment it is trivial to drive a Triac between gate and Neutral with logic levels, but since AC is connected to long transmission lines and outside transients can reach 6kV past the meter, there are good reasons why what you ask for is unsafe.

It is trivial to put zero-crossing opto triac inside the fan. and run 20mA DC from PIC to the Fan to turn it on.