Hi all, I well played with dc motors, now i want to try ac motors,
I googled and found Arduino Playground - ACPhaseControl but unfortunately i could not find the main components viz. H11AA1, MOC3052, and the triac on some local market.
so i decided to use substitutes and come up with following,
H11AA1 substitute with MCT2E and bridge rectifier, transformer
MOC3052 substitute with MOC3021
Triac i use BT 136
I planned the following schematic pls see attached images : zeroCrossDetector.png and switch.png.
now before ordering the components i need your advice, pls first check the circuit ---- is everything OK ?
if any thing wrong etc pls tell me.
is there any way to eleminate the 12-0-12 transformer, it looks very bulky ?
i selected R1 to be 1k in zeroCrossDetector.png is it OK and safe for the MCT2E ?
and one thing more is there any way to control the direction of motor also
pls reply soon, so that i can order the parts and start further....
The MCT2E is no good, its not an AC sourced opto-isolator - look at the datasheet for
the H11AA1 - see the two LEDs on the opto isolator input side? That means it works with
AC. This is a requirement.
The MOC3021 needs 3 times as much current to trigger compared to the MOC3023, which
may make it fail to trigger, depending on the tolerance of the circuit. You would be safer
finding an opto-triac that has the same trigger current as the MOC3023, ie 5mA.
I think the transformer is used to capture mains voltage zero-crossings - however this is not
the same circuit as in the playground example, which uses the H11AA1 opto-isolator to detect
zero crossings directly from the mains - avoiding the need for a transformer, but requiring
some sort of power supply for the microcontroller.
By the way what kind of motor are you trying to control? If its an induction or synchronous
motor give up now - these require variable frequency drive. Universal motors are OK to
control via triacs, but you will need a good snubber circuit.
ashuarduino:
thanks for reply, actually as i said i could not get H11AA1, moc3023 on a local market also not online in india so i have to use MCT2E and moc3021
now as MCT2E is not an AC sourced opto-isolator i am using transformer and bridge rectifier
Why not get an AC opto-coupler? They are not exactly rare.
and for the current issue of moc3021 we can use a transister before moc3021 to supply it more current
OK, this is on the low-voltage side - but perhaps you should clarify the exact circuit you are proposing now,
it may already provide enough current.
for playing i just want to start with control a simple home ceiling fan or exhaust fan motor
I repeat if the motor is an induction or synchronous motor, give up any idea of trying
to speed control it without a VFD. Doesn't matter what the motor is for, it matters only
what type of motor. You can control universal motors, but universal motors are not often used
for fans because they are very noisy and have a short service life. Try to control induction
motor with a triac and you will likely blow up the triac and overheat the motor.
You can use two MCT2E's in place of an H11AA1 - just requires more components.
(See attached.)
D1, D2 should have PIV suitable for your situation and choose resistors for 10ma or so.
