controlling a hotwire

[cncmachineguy]

Hello all, I am back to trying to get this done. Any suggestions on the transformer in the melabs example? I don't need the power supply side, so really I guess I just need the zero crossing sync.

So basiclly, a logic level TRAIC (as linked by Dave) connected to an output and a way to detect the Zero crossing is all I need, Yes?

[kellyseye]

Hello all, I am back to trying to get this done. Any suggestions on the transformer in the melabs example? I don't need the power supply side, so really I guess I just need the zero crossing sync.

So basiclly, a logic level TRAIC (as linked by Dave) connected to an output and a way to detect the Zero crossing is all I need, Yes?

Exactly.

The transformer must be rated for at least the maximum power you would expect to use plus a margin for safety. Since the VA rating defines the power, you could be very adaptable on the choice of transformer in terms of volts and current but, generally speaking, keeping the volts low (<24VAC) and the current high (probably around 3A to 5A) is safer for the user.
There would be a quite large selection available on the likes of eBay if you search.

[cncmachineguy]

half asleep, but here is my beginning. Looking for some help here if anyone wants to help me fix this

[mister_e]

The cool thing of Triac is they often come short when they burn. So ask yourself if it's safe to plug it to the Main first. If the wire break... how dangerous it will be if someone try to change it LIVE.

Kinda stuff like that

[Jerson]

I recommend you look up the MOC3021 opto-triac to interface your triac to the PIC. Your current scheme does not seem workable.

[cncmachineguy]

About my schematic: The values for the resistors are just the default values. I know they are not correct. The cap for the input to the opto's, I have no idea what value this should be. Also have no idea yet as to which opto style I want for the zero crossing side of things. Maybe neither? And I see I have connected the top opto incorrectly. I ment to groung the emitter and take the signal from the collector.

@ Steve, Are you trying to remind me I need a fuse on the wire side?

@Jerson, I am under the impression using a logic Triac, with 10mA gate will work as I drew it. If I am wrong about this, feel free to tell me and I will add the opto.

@ Moderators, if this should now be moved to the schematic section, please move it. Thanks

[Jerson]

Hi Bert

I was not sure I had something that I could screen-grab. But, here it is. The opto input was used with a 12V circuit, however, you may use 5V and scale the resistor accordingly.




Regards

[Archangel]

@ Steve, Are you trying to remind me I need a fuse on the wire side?

Hi Bert,
I think Steve is saying to include a circuit to protect the operator from electrical shock, GFI and proper machine grounding so you do not become roasted.