mystery signal

Dave Houston · 2005-11-11T16:02:54+00:00

I'm seeing a nearly continuous 2Vpp 120kHz signal on one 'phase'. The other'phase' is clear. There are what resemble triac noise bursts approximately1.6ms after each zero crossing and the 120kHz seems to be in sync with them.I say nearly continuous because the signal is absent on what appear to berandom half cycles (again in sync with the triac-like bursts, 1.6ms pastZC).I say 'phase' because while the two circuits seem to have no communication,they are in phase when observed on a scope. My apartment was originally twoapartments and there are two meters which might be a factor.The signal is not coming from anything in my place but there are 4apartments in the building and 4 more in another building across the streetwhich shares the transformer.A random snapshot of 24 half cycles is 101101101110111110110110 with 1indicating 120kHz presence and 0 its absence. I've been unable to discernany clear pattern other than the OFFs never last beyond a single half cycle.The triac noise pulses have been here for a few years but yesterday was thefirst time I saw the nearly continuous signal. It blocks X-10. It shows upas noise on my ESM1.Any ideas?

mystery signal

Nov 11, 2005 23 Replies

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Marc F Hult 20 years ago

dimmer] circuit designs.

I don't know in what equipment other than dimmers and large UPS's IGBT's are currently being used, but as I wrote before, the list of device that they are being touted for by semiconductor mnufacturers is long:

Washing Machine Air Conditioner HVAC (Compressors, Blowers, Pumps) Refrigerator Small Motor Control Traction Inverter UPS Power Supply Servo Drive Medical Power Supply Motor Drives Inverter Welding

etc

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Lotsa new stuff potentially adding to the powerline cacophony.

HTH ... Marc Marc_F_Hult ww.ECOntrol.org

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Marc F Hult 20 years ago

There's someone living in my house who volunteers to do so. I'm very sure that he even has an ELK X-10 powerline monitor and portable oscilloscope ;-)

... Marc Marc_F_Hult

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