triac circiut not working - Electronic Circuits Projects Diagrams Free

subzero349 · 27th June 2003, 06:58 PM

Sebi has posted the circuit I am using in the projects folder

I am trying to get a triac and optocoupler to turn on a light bulb (120Vac) when a bit from a microcontoller goes low...

If I put a capacitor across MT2 and MT1 the light is ALWAYS ON no matter what the microcontroller is...

If I don't put a cap across MT2 and MT1 the light is ALWAYS OFF not matter what the microctonroller is....

Any suggestions?
Any recommendations for triacs that are for 120Vac approx 8amps?

Please help! I've seen a lot of circuits that are all the same as Sebi's and they are supposed to work... but mine is not!!!

subzero349 · 27th June 2003, 08:25 PM

I am using a small neon lamp... could this be why it's not working?

Sebi · 27th June 2003, 10:27 PM

Ahhhh... neon lamp! (glimm) it have very small current consumption! Can work via serial condenser. Try the circuit with a small bulb (min.5..10W) The 0.5ma of glimmlamp not enough for TRIAC proper work.

subzero349 · 2nd July 2003, 08:12 PM

Thanks to Sebi for the help...
I am now using a 100W light bulb and the circuit works!

Sebi gave me the following circuit to work with (keep in mind not all triacs have the same pinout)

Sebi · 2nd July 2003, 09:29 PM

And how can You attached this image here?

Mosfet · 2nd July 2003, 10:06 PM

When you use the "Img" button during "Post a reply"
and insert the URL for a picture.

Mosfet · 2nd July 2003, 10:14 PM

Right click on any picture and select properties to get a picture's URL.

regards Sebi

Sebi · 3rd July 2003, 05:29 AM

And here is a circuit for strong inductive loads. It work for me to switching 3phase motors also properly.
Thanks, Mosfet here is the pic

subzero349 · 3rd July 2003, 02:41 PM

Thanks Sebi... the circuit for inductive loads doesn't seem to show up on my computer

Sebi · 3rd July 2003, 04:14 PM

After attaching it was visible...
I've posted it to Projects forum.

subzero349 · 3rd July 2003, 04:25 PM

Thanks, here's another question:

I'm using a PIC 16c715 for the logic to turn the opto/triac off and on.

The only port pin I have available is OPEN COLLECTOR (the board I am using also has a 4k7 pull up resistor).

I have not been able to get the Triac circuit to work with this OPEN COLLECTOR. Although when I measure the o/p with a probe I can get it to change from high to low...

Should I consider sourcing the current instead?

subzero349 · 3rd July 2003, 05:35 PM

Nevermind... the OPEN COLLECTOR sinks current just fine... I just made a mistake...

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27th June 2003, 06:58 PM	(permalink)
subzero349	triac circiut not working Sebi has posted the circuit I am using in the projects folder I am trying to get a triac and optocoupler to turn on a light bulb (120Vac) when a bit from a microcontoller goes low... If I put a capacitor across MT2 and MT1 the light is ALWAYS ON no matter what the microcontroller is... If I don't put a cap across MT2 and MT1 the light is ALWAYS OFF not matter what the microctonroller is.... Any suggestions? Any recommendations for triacs that are for 120Vac approx 8amps? Please help! I've seen a lot of circuits that are all the same as Sebi's and they are supposed to work... but mine is not!!! __________________ subzero

27th June 2003, 08:25 PM	(permalink)
subzero349	I am using a small neon lamp... could this be why it's not working? __________________ subzero

27th June 2003, 10:27 PM	(permalink)
Sebi	Ahhhh... neon lamp! (glimm) it have very small current consumption! Can work via serial condenser. Try the circuit with a small bulb (min.5..10W) The 0.5ma of glimmlamp not enough for TRIAC proper work.

2nd July 2003, 08:12 PM	(permalink)
subzero349	Thanks to Sebi for the help... I am now using a 100W light bulb and the circuit works! Sebi gave me the following circuit to work with (keep in mind not all triacs have the same pinout) __________________ subzero

2nd July 2003, 09:29 PM	(permalink)
Sebi	And how can You attached this image here?

2nd July 2003, 10:06 PM	(permalink)
Mosfet	When you use the "Img" button during "Post a reply" and insert the URL for a picture.

2nd July 2003, 10:14 PM	(permalink)
Mosfet	Right click on any picture and select properties to get a picture's URL. regards Sebi

3rd July 2003, 05:29 AM	(permalink)
Sebi	And here is a circuit for strong inductive loads. It work for me to switching 3phase motors also properly. Thanks, Mosfet here is the pic

3rd July 2003, 02:41 PM	(permalink)
subzero349	Thanks Sebi... the circuit for inductive loads doesn't seem to show up on my computer __________________ subzero

3rd July 2003, 04:14 PM	(permalink)
Sebi	After attaching it was visible... I've posted it to Projects forum.

3rd July 2003, 04:25 PM	(permalink)
subzero349	Thanks, here's another question: I'm using a PIC 16c715 for the logic to turn the opto/triac off and on. The only port pin I have available is OPEN COLLECTOR (the board I am using also has a 4k7 pull up resistor). I have not been able to get the Triac circuit to work with this OPEN COLLECTOR. Although when I measure the o/p with a probe I can get it to change from high to low... Should I consider sourcing the current instead? __________________ subzero

3rd July 2003, 05:35 PM	(permalink)
subzero349	Nevermind... the OPEN COLLECTOR sinks current just fine... I just made a mistake... __________________ subzero