I have desined a circuit with a Triac (BT139) to swith an AC Motor that works with 220 VAC. (Go to this link to see my Circuit
formatting link
) I have used a MOC3063 Optocoupler with Phase Detector capabilities. I seems work fine. but after some times (maybe some hourse) after running the circuit fails and the motor will vibrate and will not rotate. this problem will be solve if i change the MOC3063 with new one. but the same will happen with the second ic. my question is , should i select another range of resistors with the MOC3063 ?
"Omid" wrote in news: snipped-for-privacy@b28g2000cwb.googlegroups.com:
This reminds me of a problem with the Siemens touch dimmer IC SLB0586A. Maplin (UK elctronics retailer) had a design in their catalog that specified a signal diode between the control pin on the IC and the triac gate, anode toward the IC output. Even this wasn't enough Those IC's kept blowing out. I 'corrected' this in my own way by adding a 220R resistor in series with the diode. I urged Maplin to update their catalog with the amendmentm but they never did. The shop staff recognised the correction and refunded all the blown IC's which at a fiver each was pretty good.
Try adding both the diode and the 220R, if the circuit won't fire, try either a more sensitive triac, or omitting the resistor.
"Omid" schreef in bericht news: snipped-for-privacy@b28g2000cwb.googlegroups.com...
You should find the datasheet of the MOC3063 (and the one of the BT139 as well). From the first you can learn that the emitter requires 5mA for normal operation. With that 1k8 (R1) you provide less then 2mA. So lower that resistor to - let's say - 470 Ohm and you have at least one problem solved.
"petrus bitbyter" wrote in news:45043106$0$12425$ snipped-for-privacy@dreader32.news.xs4all.nl:
Why exactly would an undercurrent burn out an IC that was working fine at first? If it were that, the IC would be fine, but would never have appeared to work right.
Superficially you might see a failure after many hours working as the battery discharged, but I doubt that changing the optocoupler could make that recover, unless the time taken was long enough to allow a limited and temporary recovery of voltage, which I doubt would happen, as the battery would have to be very stricken if it could not supply the 2 mA asked of it. It can't be contantly discharged through a non-latching switch anyway.
The only way I think the low current could cause this is if the optocoupler isn't damaged, but just reduces sensitivity either to light, or the LED to current, in the course of the first few hours.
"Lostgallifreyan" schreef in bericht news:Xns983AADC546BCDzoodlewurdle@140.99.99.130...
Really?
As far as the circuit drawing tells, the battery has to provide current as long as the motor runs.
That's not unthinkable. Even maybe the reason to specify a minimum current of 5mA. It's easy to find out. Increase the current and look what happens. According to the datasheet you can go as high as 30mA. However, the emitter will not be damaged by too low a current but the detector might be damaged by too low a light level.
"petrus bitbyter" wrote in news:45046000$0$17845$ snipped-for-privacy@dreader24.news.xs4all.nl:
Interesting. The battery could be implicated then, circumstantially, but the real issue would be the low current. I take it you mean that by too low a light level, the effective resistance rises in the detector, making it vulnerable, wheras normally it might be too light (low resistance) or too dark (high resistance) to be at risk?
Raising the LED current is wise, and I agree, it will be the right test, but I think there still needs to be some safeguard there. In this case that diode I mentioned wouldn't work, I think, even though it was used in the triac drive from the Siemens lamp dimmer IC, but the resistor might.
The BT139 data sheet specifies a gate current of 60 mA for latching, but a peak gate current up to 2 amps! The 220R resistor between the optocoupler and gate should limit this to a peak below that which would kill the transistor in the coupler, no matter what the LED was doing. That same protection might also be enough to avoid any need to use the relay which Homer Simpson (!) suggested.
A relay is inexpensive, reliable, visual, provides a high level of isolation and removes the load considerations from the triac. You can test the circuit without the motor.
"Homer J Simpson" wrote in news:gq_Mg.1508$bf5.1294@edtnps90:
I agree with all points there, but we have an optoisolator to consider, which puts the operator safe, and the resistor I suggest adding to limit the peak gate current is surely cheaper than any relay. As triacs are often specifically intended for motor control, it's surely a case of making the most effective use of them. If you're using a relay, why use a triac at all?
"Lostgallifreyan" schreef in bericht news:Xns983AD532EE3B0zoodlewurdle@140.99.99.130...
Well, these type of switches should be on or off. No current through the LED will be off. Enough current wil switch it on. But what happens in between? The data sheet tells little about it, but the first thing I'd do is make sure the LED current to be enough. Just to stay on the safe side.
The 390 Ohm resistors should be enough to limit the gate current. These resistors may be lowered to make sure the gate current can become high enough but I should not go below 270 Ohm. It's the last thing I'd try.
The gate trigger current of the BT139 is 10mA typically and 35mA worst case. The 2A peak current is the maximum the gate of the triac can handle. So this triac is even better then the FKPF12N60 mentioned in the MOC6063 datasheet. You can also find a 10nF in the snubber circuit instead of the 100nF found in the OPs schematic. I consider 100nF too high and I'd lower it to 1-10nF.
For me I've the next guess: Due to some of the causes mentioned above some parameters shifted during burn in. The MOC6063 also may be damaged. Now the zero crossing circuit blocks the detector as the voltage rises above 12V before the gate current becomes high enough to trigger the triac. At the end of the half sine, the voltage falls below 12V and the triac is triggered just before zero crossing switches it off again.
Use a 5V wall wart power supply instead of the battery; read the reply you got from Petrus (change the 1.8K resistor), and update your schematic to indicate a toggle switch instead of a pushbutton.
You got too many responses that might hide the problem identified by Petrus: you are not driving the LED hard enough.
"Omid" schreef in bericht news: snipped-for-privacy@q16g2000cwq.googlegroups.com...
I agree but too less light may disturb or damage the detector (fototriac) and/or the zero cross circuit. Once you drive the LED hard enough, you've eliminated one possible cause of the problem(s).
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.