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Mains duty cycle controller IC


trafo
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I remember twelve years ago a Siemens IC which needed a 7VDC external reference and would detect Mains AC zero crossing point and switch on and off at this point for duty cycle control. I used it for a fan speed controller. I would like very much to identify this IC and application note. The benefit was no RFI at all and very stable control. Please help if you can. Thank you.

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Thank you for the welcome and the interest. I was looking for a Siemens IC that would trigger a triac at zero crossing point of the mains supply to control the duty cycle of the AC 230V mains for speed control of a fan or other load without generating any RFI. This particular IC was an elegant solution even though it required a tiny Xformer to give it a 7VDC reference. If there is a more suitable solution with a low parts count that will achieve the same purpose, I will be happy to consider it. Thank you again.

Trafo

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OK. I live in a tropical climate where we use ceiling fans quite a lot to keep cool. The old controllers were heavy autotransformers with multiple tappings and a rotary switch to select your voltage to drive the fan. Now with rising material cost and the cheaply available light dimmer, that's what is being supplied with fans. Trouble is that these generate a good deal of RFI. I had made one controller with the Siemens IC that controlled the duty cycle of the triac which controlled the fan speed and left it in a house I once inhabited. I would like to be able do this again. I would prefer to use a twelve way rotary switch to select fan speed.

Thank you for your interest.

Trafo

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Ante,
I thank you again. I have looked at the Motorola device and want to say that the Siemens device did this - perhaps without opto-isolator - but it also provided the duty cycle timing drive to the triac.
I wish I had the circuit - the device I built was straight from the application note and I used a triac readily available in our poorly stocked parts stores. Any other suggestions for achieving the speed control by duty cycle control would be greatly appreciated.

Trafo

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Ante,
I am 64 yrs old now and beginning to forget a lot, and I had that IC for a few years before I built the device with some help from a friend who found the application note for it - now he is gone and I suppose I will be too in the not too distant future!

But one should keep trying. I have wanted to trace this IC or a similar one for a number of years, but it was only since last week that I have full time internet access that allows me to go to sites like this one to try to find things with help from good people like you.

Trafo

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I wish you were right. The building was torn down a few years ago and I have no idea if someone really smart decided to save my little circuit. I don't think there is any hope there. Which reminds me that I remember a childhood friend's house 1,200 KMs away from where I live that used to have a ceiling fan in the dining room that was an old - dating from the thirties - British two bladed fan that had a span of almost three metres and it turned so slowly that each time it went around one felt a whoosh of a breeze in a nice quiet way, and last year I saw that the building was in a bad way and learnt that it was going to be sold as my dead friend's remaining family were now living in town houses. A few hours later I began to wonder if the fan could be "rescued". Unfortunately, I did nothing about it, and it is probably gone now. "Sic transit gloria mundi".

Trafo

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