[SOLVED] Doubt with triac circuit

[alah]

Hi, Im usng the attached circuitto control an AC motor with a uController. The transistor is an opto, an ICLT6 chip. I tried ith a 100 ohm resistor but the voltage across MT1 and MT2 measures 50v AC. I lowered the resistor to 27 ohm but still MT1-MT2 voltage is 25. The dc voltage of the emitter is 1.4 so its drawing 130mA, which seems too much. Any idea? Thanks.

 

[D.A.(Tony)Stewart]

What schematic? Part list? Load?

Sounds like device specs exceeded

 

[schmitt trigger]

There is no attached circuit in your post. Please attach an image such that we can review your design.

The ICLT6 is a dual phototransistor coupler. There are ways to drive a Triac with phototransistors, but requires an isolated and floating DC source. It is usually better to drive them with a phototriac coupler. Like the MOC3020.

 

[alah]

hope the image upoads,it said so. I clicked on "add image", opened it, clicked on "thumbnail" and upload I know I have how to use fototriacs but I have a bunch of these thought I should use them.

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[schmitt trigger]

This is a very odd ball circuit to produce phase control with a Triac. Odd ball and un_necessary, specially since proper opto triac drivers have been around for over 30 years.

My advice is still valid. Use an opto triac driver.

Having said that...you don't plan using phase control on an AC induction motor? Do you? This only works for small, shaded pole (low torque) motors and just barely.
Induction motors require variable voltage and frequency drives.