View Full Version : Relay troubles


jwatte
08-30-07, 10:24 PM
I have a dedicated 20A circuit that powers my speakers and TV. I have one of the 12V outputs from my AVR trigger this circuit through a solid-state relay from Automation Direct (AD-SSR25). Unfortunately, I can hear a faint buzz from the speakers when they are in idle. If I disconnect the relay, and wire the cable such that it's always on, the buzz disappears, so it's the relay causing it.

As far as I know, the SSRs actually work much like dimmers, except with a low set-point to get close to the "full" waveform through. Unfortunately, enough EMI gets through to cause problems in the speakers (which are internally bi-amped). (See, there's an argument that power conditioners can work in certain circumstances!)

This relay is mounted in a 7"x7" electric box in the wall, with an access door, so I can actually replace it (yay!).

Now, I'm looking for a 20-30 A relay with 12V coil that doesn't have this problem -- probably an electro-mechanical device. AutomationDirect doesn't have a suitable relay, but I found the following at Digi-key, which might work alright. I'm mostly worried about thickness, because the electric box is not very deep.

http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=255&M=HE2AN-S-DC12V

Does anyone have another relay to recommend? I'd like to spend well under $50 for this replacement, as all my remodeling, HT upgrades, and vacation have totally drained available cash.

jwatte
08-31-07, 04:50 PM
Nobody know of a good relay?

And I can't believe my jab at the power conditioner detractors didn't at least raise an eyebrow. Perhaps I should ask in the $20k forum on that topic ;-)

PLincoln
09-04-07, 01:43 PM
This is what I used

http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=PB847-ND

Digi-Key Part Number PB847-ND
anufacturer Part Number KUHP-11DT1-12

Technical/Catalog Information PB847-ND
Standard Package 25
Category Relays
Family General Purpose
Vendor Tyco Electronics/Potter & Brumfield
Coil Voltage 12VDC
Contact Rating 20A
Circuit DPDT
Mounting Type Chassis Mount
Features Non Latching
Lead Free Status Lead free
RoHS Status RoHS non-compliant
Other Names KUHP-11DT1-12
KUHP-11DT1-12-ND
PB847
PB847-ND

jwatte
09-11-07, 02:17 AM
I ended up with another relay from digi-key, because that relay had insulated screw terminals, thus was easier to hook up.

http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=255&M=HE2AN-S-DC12V

I'm glad to say that it cured my tweeter buzz problem, but I'm quite unhappy that quite high end reference monitors would have that problem.