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inductive or resistive load

Hi, all. This is my first post in this group. I'm trying to make a board for controlling AC loads. I mean to be able of swithing on/off the AC power supply. I have seen a lot of examples around the internet, and most of them use the typical I/O pin

  • opto-triac+triac, for example, this one:

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I made a very similar board but it didnt work and i dont know why. I used MOC3011, BT16A, and a GPIO from a microprocessor.I would like to be able of a remote turning on and off some of the equipments of my lab, and most of them are powered by classical AC/DC adaptors, so I want to turn on and off the AC input of every adaptor of the equipments. The first question is: what kind of load is an AC/DC adaptor, assuming that the total consumption of the equipment that it feeds is about 50 watts: inductive or resistive? Since they usually have a transformer as the first component that sees the AC input, I supposed it's inductive... am I right? Another question about the triggering. If the led is always lightning (feeded by a gpio, for example), the final triac should be at on-state so that the adaptor would be powered on? A while after, if I drive low the gpio turning off the led, should the adaptor power off??? Is it an optimal approach for this problem? What is the real benefit of using zero crossing detectors? I read a lot about controlling the amount of power given to lamps or other devices, but i dont want controlling the amount, but only the on/off state.

Thanks in advance.

Reply to
Cepowak
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first thing you must do is place a volt meter across the LED diode of the isolator.. See if you're getting the required drive voltage. Also, I assume you're leaving the trigger signal on at all times until you want to turn it off ? Putting that aside, you may also want to check a couple of other things, and that is the resistor you have going to the coupler that drives the gate.. The gate current needed for trigger may be more than what your giving it.

Things to ponder on..

--
"I\'d rather have a bottle in front of me than a frontal lobotomy"
http://webpages.charter.net/jamie_5
Reply to
Jamie

I think the LED is well powered. It has 1.15 volts across it. The datasheet of the opto-triac shoes that the Vd should be 1.2 so i think it's right. I have 2 resistors of 100ohms in series ( i hadnt another type when i made the experiment) with the gate of the triac. Maybe I should use lower values?

Thanks

Reply to
Cepowak

put your ma meter in series with the LED feed and see what current readings you're getting.. You maybe just on the threshold of it. Also, If you jump the gate of the Triac to the feed side of the isolator, you can determine if the resistors you're using have sufficient current for the TRIAC.. Use this approach to determine the problem. If the TRIAC is comes fully on, then, this means you have an Optical coupler issue. if it does not turn on, then you have insufficient gate drive.. You also need a minimum load of course on the output to test this. You need to get above the holding current of the TRIAC.. for now, You could use a incandescent lamp as your test load.

--
"I\'d rather have a bottle in front of me than a frontal lobotomy"
http://webpages.charter.net/jamie_5
Reply to
Jamie

lobotomy"

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Ok i will try that, but, do you know the answer of the question about if an AC/DC laptop adaptor is an inductive or a resistive load?

Thanks in advance.

Reply to
Cepowak

"Cepowak"

** It is neither.

The load is " non linear ".

Current is drawn in pulses at the time of the each sine wave peak.

Voltage and current are essentially in phase.

....... Phil

Reply to
Phil Allison

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