Embedded Systems Conference
Breaking News
Comments
Newest First | Oldest First | Threaded View
Guru of Grounding
User Rank
Author
re: Conducted emissions--NOT
Guru of Grounding   12/10/2010 1:44:11 AM
NO RATINGS
To auddoc: While I haven't seen the schematic of the CDZ500, I'll assume that its output is unbalanced and I'll guess that it's "muting" takes the form of a series switch on the high side of its output. When the switch is open (output muted), the crossover/amplifier input can't "see" the signal or ground reference (which has the buzz voltage). You can contact me directly if you like, with more details, at whitlock@jensen-transformers.com.

auddoc
User Rank
Author
re: Conducted emissions--NOT
auddoc   12/9/2010 10:10:32 PM
NO RATINGS
Any idea on what would cause a typical sounding 60/120Hz buzz with a U-grounded Pro-crossover/power amp rack, driven by a TEAC CDZ500 directly?... but only when the CD player typical output section muting FETs are unmuted, as ONLY in Play mode. Also dead-quiet in Pause or Stop mode. Cd player sounds dead quiet into standard two prong AC powered Pioneer integrated amp plugged into the identical AC source!!! I have 30+ years in this and am scratching my head.

Guru of Grounding
User Rank
Author
re: Conducted emissions--NOT
Guru of Grounding   12/8/2010 10:47:45 PM
NO RATINGS
As someone who specializes in troubleshooting studio-grade audio equipment (and systems) for noise coupling issues, I amazed at how much basic physics is forgotten or ignored by most engineers. Coupling, whether capacitive or inductive, is proportional to the rate of change in voltage or current. A good example is a system that's free of audible hum and buzz ... that is, until an ordinary light dimmer causes fast-rising currents to flow in AC power wiring. The inductive coupling of this into the ground system will reveal "latent" coupling mechanisms (especially in unbalanced signal interfaces, which have no inherent ability to reject ground noise).

antiquus
User Rank
Author
re: Conducted emissions--NOT
antiquus   12/7/2010 8:48:10 PM
NO RATINGS
This reminds me of my first job as a EE Technician. One of my first assignments was to breadboard four copies of an audio processor that had both input and output transformers. These were rather large and heavy, so I positioned them at one end of the board and built the circuit in a "U" shape, with the digital controls elegantly at the other end. One function of the circuit was to disable the output audio by means of a digital input. The engineer-in-charge was polite but disappointed when the in-out isolation test failed, and explained to me that putting two transformers so close to each other would inevitably lead to crosstalk. I spent the rest of the afternoon moving the output stages to the other end of the PCB.

agk
User Rank
Author
re: Conducted emissions--NOT
agk   12/7/2010 10:20:19 AM
NO RATINGS
These are highly critical and for every application we need to solve them differently.A standard set of ideas or solutions are not sufficient. One need to work hard to find out the reasons and solve the conducted and radiated emmissions.

zeeglen
User Rank
Author
re: Conducted emissions--NOT
zeeglen   12/6/2010 4:22:55 PM
NO RATINGS
Jon, sounds like you're the guy with experience that others come to for help when they're stumped. You mentored someone by demonstrating how a scope probe makes a great 'sniffer' for detecting radiated fields and how to use metal shields to block these fields. Good stuff to know. Your colleague learned from you, and many reading this story may have just gained another incremental bit of knowledge that might be useful someday. Thanks for sharing.



Radio
NEXT UPCOMING BROADCAST

As we unveil EE Times’ 2015 Silicon 60 list, journalist & Silicon 60 researcher Peter Clarke hosts a conversation on startups in the electronics industry. Panelists Dan Armbrust (investment firm Silicon Catalyst), Andrew Kau (venture capital firm Walden International), and Stan Boland (successful serial entrepreneur, former CEO of Neul, Icera) join in the live debate.
Flash Poll
Top Comments of the Week
Like Us on Facebook

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
Special Video Section
The LTC®4015 is a complete synchronous buck controller/ ...
10:35
The LT®3042 is a high performance low dropout linear ...
Chwan-Jye Foo (C.J Foo), product marketing manager for ...
The LT®3752/LT3752-1 are current mode PWM controllers ...
LED lighting is an important feature in today’s and future ...
Active balancing of series connected battery stacks exists ...
After a four-year absence, Infineon returns to Mobile World ...
A laptop’s 65-watt adapter can be made 6 times smaller and ...
An industry network should have device and data security at ...
The LTC2975 is a four-channel PMBus Power System Manager ...
In this video, a new high speed CMOS output comparator ...
The LT8640 is a 42V, 5A synchronous step-down regulator ...
The LTC2000 high-speed DAC has low noise and excellent ...
How do you protect the load and ensure output continues to ...
General-purpose DACs have applications in instrumentation, ...
Linear Technology demonstrates its latest measurement ...
10:29
Demos from Maxim Integrated at Electronica 2014 show ...
Bosch CEO Stefan Finkbeiner shows off latest combo and ...
STMicroelectronics demoed this simple gesture control ...
Keysight shows you what signals lurk in real-time at 510MHz ...