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subaruzero 27th September 2006 06:44 AM

need dpdt switching relay help
Hi all, my first post here. I found a similar thread on this site after browsing the internet for hours trying to learn more about what I want to do. I figure its time to ask for some help!

I will be putting a dpdt switching relay in a speaker cabinet and wire it in directly (soldering) before connection to the speaker. This will be for polarity reversing purposes. I am pretty sure the dpdt switching relay needs to be latching. I think the input signal will be a pulse from a 12V battery. Here are some of my many questions:

1. When the impedance is listed for the relay, what exactly is it listed for?

2. Since the relay will be wired in right before my speaker, I would think it should have as little impedance as possible, is that right?

3. What manufacturers would make a higher quality component for this audio application...without being unreasonable in price?

4. I plan to have an input pulse from two different sources. One source to switch the polarity, and the other source two switch it back. I should therefore have a dual coil switching relay?

I'm sure I'll probably have more questions if I receive replies, but let me know if you have any thoughts and suggestions. Thanks!

AndrewT 27th September 2006 08:27 PM

1. The relay coil resistance will determine the current drawn from the control circuit. More current =more heat in the coil to be dissipated.

2. The speaker draws the signal through the contacts. The resistance of the contacts should be in the mohms (0.001r to 0.009r) range. As the contacts become dirty or pitted the contact resistance will rise.


4. It will be difficult enough to source a suitable relay for speaker duty that can carry tiny to maximum speaker current, for the contacts to be self cleaning, that have long life and for occassional live switching use to survive breaking nearly DC into inductive load without adding latching to the spec. I do not recommend live switching use.

Build your own latching circuit using another two small signal relays in the control circuit side.

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