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zika1212 said:i'm controlling a 220 V ,50 Hz AC heater using PIC 16F876 (4 MHz clock) by Pulse Width Modulation ... do i need a synchronising circuit ?? if yes, how should i connect it ??
Nigel Goodwin said:zika1212 said:i'm controlling a 220 V ,50 Hz AC heater using PIC 16F876 (4 MHz clock) by Pulse Width Modulation ... do i need a synchronising circuit ?? if yes, how should i connect it ??
Thanx for the information..
the heater is just an element
is that mean that the synchronising is done through the program ??
and
what is the best or easiest way to interface the PIC with the heater (block diagram if available) ??
zika1212 said:Nigel Goodwin said:zika1212 said:i'm controlling a 220 V ,50 Hz AC heater using PIC 16F876 (4 MHz clock) by Pulse Width Modulation ... do i need a synchronising circuit ?? if yes, how should i connect it ??
Thanx for the information..
the heater is just an element
is that mean that the synchronising is done through the program ??
Yes, you need to generate a zero-crossing pulse, you can do this from the output of a bridge rectifier, it's a common technique.
and
what is the best or easiest way to interface the PIC with the heater (block diagram if available) ??
I would suggest an opto-coupler feeding a triac, this will isolate the PIC circuit from the mains.
You can actually buy opto-coupled triacs with in-built zero-crossing circuits, these can simply feed larger triacs. This would reduce your PIC section to just turning a pin ON and OFF at the required ratio.
Nigel Goodwin said:zika1212 said:Nigel Goodwin said:zika1212 said:i'm controlling a 220 V ,50 Hz AC heater using PIC 16F876 (4 MHz clock) by Pulse Width Modulation ... do i need a synchronising circuit ?? if yes, how should i connect it ??
I would suggest an opto-coupler feeding a triac, this will isolate the PIC circuit from the mains.
You can actually buy opto-coupled triacs with in-built zero-crossing circuits, these can simply feed larger triacs. This would reduce your PIC section to just turning a pin ON and OFF at the required ratio.
can u help me with a circuit diagram ??!!
Nigel Goodwin said:Have a look at the datasheet here https://www.fairchildsemi.com/ds/MO/MOC3020-M.pdf, which gives examples of how to use an opto-isolated triac - this isn't the version with in-built zero-crossing, and you would need to switch at the correct time. Presumably a datasheet on the zero-crossing version is available from the same site?.