Electronics > Projects, Designs, and Technical Stuff
How to switch a speaker on and off?
Pjotr:
Have a look here at Farnell: http://nl.farnell.com/webapp/wcs/stores/servlet/Search?catalogId=15001&langId=31&storeId=10168&categoryId=700000006239&sort=P_PRICE&pageSize=25&beginIndex=1&showResults=true&aa=true&pf=110138163,110138169,110138436,110148996,110149016,110159486,110159515,110170154,110173911,110174063,110186377,110193617,110198830,110233446,110258018&min=110173911
RABeng224:
I built a "speaker router" that takes a simple 2 channel receiver and routes it to different speaker zones. I used decent quality relays and I have no issues or popping when switching between speaker zones.
rs20:
Maybe I'm overly idealistic, but I'm surprised that there's no way to just ease the amplifier in, rather than letting it have a mini-tantrum and just disconnecting it from the speakers while it does that. Like, inhibiting the upper half of the bridge and turning them on gradually so the output voltages just gently move into position.
BillW50:
Sure it is possible.
http://lmgtfy.com/?q=solid+state+audio+relay
Chris C:
--- Quote from: Starlord on July 30, 2015, 11:29:28 am ---I did look up the part you mentioned. But I could not find it on Digikey and only found one old PDF for it.
--- End quote ---
It's an obsolete part. This got me thinking about vactrols, another old optoelectronic part no longer manufactured. In the few cases when one is needed nowadays, people build their own. And that it would be a similar process to build your own SSR.
The PS710B internal diagram shows we need two N-MOSFETs, back to back. Pick MOSFETs that switch at a low gate voltage. MOSFETs intended for 3.3V operation are common.
Next, we need an isolated source of sufficient voltage for each gate. We don't need much current at all, since the gate is a capacitor. So two of these SMD 4.0V solar cells would do nicely:
https://www.sparkfun.com/products/9962
Add a light to illuminate the solar cells. LED(s) are an obvious choice. But the slow turn-on/off of a small incandescent might make for a more pleasing switch. That solar cell has best sensitivity in infrared, which incandescents produce plenty of; the incandescent can be slightly underdriven and basically last forever.
If the solar cells don't bleed off gate voltage fast enough when the light is turned off, we'll have to add two bleeder resistors to do that job.
Finally, you might want to wrap the light and solar cells together; both to prevent external light from reaching it, and to maximize the amount of light absorbed by the cells. White electrical tape looks ghetto, but does the job fine; or substitute something more classy.
There's currently an Ebay auction for two of those solar cells, US seller, $4.54 for both including shipping. The other parts you might already have on hand, or could be scavenged.
It's just an option to consider. You could opt to buy something like a CPC1020N at Digikey for $3.12, and be done with it. Well, maybe. Consider that it and others like it are built for relatively fast switching times. It switches on and off in ~0.5ms. That will soften the pop for sure, but I don't know if the result will be entirely satisfactory. You might get a thump rather than a pop, especially if the amp has a large DC offset. If so, and you don't like it, you'll end up having to build something to fade the internal LED at an acceptable rate. Whereas if you build the SSR from scratch, especially using an incandescent, you can be certain it will be slow enough!
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version