Making solid state relay with BT139 a bit confused with

[Chriss]

Hi!
I have several BT139 and MOC 3021 around and I come across my mind I could make solid state relays for AC loads like AC motors and lamps.

I know, restive and inductive loads are different, I would like to make all them to handle inductive loads, so I need also the snuber circuit if I'm not wrong.

My major problem is to setup the right value on the circuit.
I checked around the net and found tons of schematic promising to do what is written, but I'm not really trusty to them.

Can somebody pls share a working schematic how to make my relays?

Here is a schematic which looks ok for me, I would substitute the BT136 with BT139, probably not a problem.
https://www.twovolt.com/2016/11/29/solid-state-relay-using-moc3021-bt136-traic-circuit-pcb-layout/

What is this meaning in the datasheet of the triac:
Igt trigger current VD = 12 V; IT = 0.1 A; T2+ G+ ?
What is T2+ G+ standing for?

Any help I would really appreciate.

Thank you.

[nigelwright7557]

Hi!
I have several BT139 and MOC 3021 around and I come across my mind I could make solid state relays for AC loads like AC motors and lamps.

I know, restive and inductive loads are different, I would like to make all them to handle inductive loads, so I need also the snuber circuit if I'm not wrong.

My major problem is to setup the right value on the circuit.
I checked around the net and found tons of schematic promising to do what is written, but I'm not really trusty to them.

Can somebody pls share a working schematic how to make my relays?

Here is a schematic which looks ok for me, I would substitute the BT136 with BT139, probably not a problem.
https://www.twovolt.com/2016/11/29/solid-state-relay-using-moc3021-bt136-traic-circuit-pcb-layout/

What is this meaning in the datasheet of the triac:
Igt trigger current VD = 12 V; IT = 0.1 A; T2+ G+ ?
What is T2+ G+ standing for?

Any help I would really appreciate.

Thank you.

MT1, MT2 and G are the pins of a triac.

Turn on triac by applying volts across G to MT2.

[Chriss]

Thanks for fast response.

If I understand you correctly, In the schematic I put on the link, the turn on voltage is achieved through the T1 and G ?
Would this schematic work in practice?

I'm new to triac's and not really practiced with them, but I'm familiar with AC voltage and safety of mains...

I found this nice doc, maybe somebody who is new to triac can also learn from it, like me.
https://www.st.com/resource/en/application_note/dm00451014-controlling-a-triac-with-a-phototriac-stmicroelectronics.pdf

Thanks.

[Terry Bites]

I'd read this app note from ST AN437 on snubbers for inductive loads. Choose your C  and with care. CY caps and R that can safely dissipate the transient energy.

Triacs are satan's spawn. I hate 'em.
DIY dimmer trauma in childhood.

[nigelwright7557]

Thanks for fast response.

If I understand you correctly, In the schematic I put on the link, the turn on voltage is achieved through the T1 and G ?
Would this schematic work in practice?

I'm new to triac's and not really practiced with them, but I'm familiar with AC voltage and safety of mains...

I found this nice doc, maybe somebody who is new to triac can also learn from it, like me.
https://www.st.com/resource/en/application_note/dm00451014-controlling-a-triac-with-a-phototriac-stmicroelectronics.pdf

Thanks.

The circuit is part of a working circuit.
You need 5 volts between "TRIAC" signal and ground to turn it on.