Hi,
I am working on a project where I independently control two triacs
(pins B1 and B2) with 16F877 microcontroller. Before using an actual
microcontroller I thoroughly tested my triac firing code on a MPLAB
simulator just to work out any possible logic problems. I have also
ensured that if two firing angles are within three degrees of each
other (e.g. 39° and 42°), that both triacs would fire at same time.
(e.g. in this case 39°)
Anyway to the problem:
Today, I've connected the signal generator (square pulse, period=1/60
sec, 5 V amplitude) to PIN B0.This was only a test run before I would
connect a zero crossing circuit. Also I did not connect the
optocouplers yet (MOC 3023), as I wanted to see my triggering pulses
directly out of pins B1 and B2.
When I looked at my B1 and B2 (gate firing) outputs, my firing pulses
(100usec wide as set in program) fired at correct firing
angles.However, as shown in figure below, I also got some small-width
(~5usec to 10 usec) pulses before and after actual gate trigger pulse.
Does anybody know why these small pulses occur? Is it because the two
triac firing pins are next to each other?
How can I get rid of these small pulses as I am afraid that they might
trigger a triac?
I looked at a datasheet for MOC3023 optocoupler but I am not sure if
these small pulses will be problematic?
I drew only one output but the same happens on the other output. The
drawing looks a bit imprecise but it is the best I could do with
paintbrush.
Thank you
I am working on a project where I independently control two triacs
(pins B1 and B2) with 16F877 microcontroller. Before using an actual
microcontroller I thoroughly tested my triac firing code on a MPLAB
simulator just to work out any possible logic problems. I have also
ensured that if two firing angles are within three degrees of each
other (e.g. 39° and 42°), that both triacs would fire at same time.
(e.g. in this case 39°)
Anyway to the problem:
Today, I've connected the signal generator (square pulse, period=1/60
sec, 5 V amplitude) to PIN B0.This was only a test run before I would
connect a zero crossing circuit. Also I did not connect the
optocouplers yet (MOC 3023), as I wanted to see my triggering pulses
directly out of pins B1 and B2.
When I looked at my B1 and B2 (gate firing) outputs, my firing pulses
(100usec wide as set in program) fired at correct firing
angles.However, as shown in figure below, I also got some small-width
(~5usec to 10 usec) pulses before and after actual gate trigger pulse.
Does anybody know why these small pulses occur? Is it because the two
triac firing pins are next to each other?
How can I get rid of these small pulses as I am afraid that they might
trigger a triac?
I looked at a datasheet for MOC3023 optocoupler but I am not sure if
these small pulses will be problematic?
I drew only one output but the same happens on the other output. The
drawing looks a bit imprecise but it is the best I could do with
paintbrush.
Thank you
