Hi All: I am new to this forum but have always found the subject of over unity awesome!!! But I have an off topic question regarding speakers. There seems to be an overabundance of very intelligent people here, and I thought this would be the perfect place to ask!! I am trying to hook up two devices to one speaker and I dont want to get bleedoff back into the other system, how do I do this?
Quote from: Dr on May 23, 2010, 11:25:20 AM
There seems to be an overabundance of very intelligent people here, and I thought this would be the perfect place to ask!!
A gentleman of obvious Insight! :D and one of the more esoteric areas
of electronics circuits. The thing you want is variously referred to as an
electronic hybrid circuit.
The following terms all reference the same sort of device;
echo cancellation/suppression, telephone sidetone generator,
telephone talkback suppressor, signal duplexor, audio hybrid circuit.
Without getting too complex here is a link to what you would like;
http://en.wikipedia.org/wiki/Hybrid_coil
There are three types of audio hybrid circuits;
a) Dynamic circuit involving amplifiers - absolute duplexor - requires ext. power
b) Passive circuit involving transformer signal cancellation - will not suppress small
power signal leakage (above link)
c) Roll your own using a 5V latching relay. - absolute switched connection
What I would do (this goes for big speakers not earphones.) is couple a hand
built power supply to each audio line via capacitors or audio transformers looking
for 3 to 5 Vdc to build up over a reasonable time period of low level audio. So,
isolation into a full wave bridge rectifier with some reasonable size electrolytic
capacitor (100uf) for dc filtering running into back to back zener diodes for
voltage limiting into a CMOS NE555. The CMOS IC would be set to pulse at 75
to 100ms. wide every 200ms rate. One for each audio channel with the NE555's
pulsing into a single 5volt latching relay. A latching relay has one coil for setting
and another coil for re-setting. The relay would enable whichever audio line's
NE555 was pulsing and the other would be disconnected. The relay would connect
the appropriate audio lines to the speakers and keep that pair connected forever
until that side was turned off and the other side audio was turned on. Because
the connection is a mechanical switch these units could be strung together and
represents total circuit isolation.
Link explaining latching relays;
http://en.wikipedia.org/wiki/Relay#Latching_relay
A link of circuit for explanation of relay function (only);
http://www.discovercircuits.com/PDF-FILES/LATCHRELAY1.pdf
TX2-L2-5V PANASONIC DPDT Latching Relay
http://parts.digikey.com/1/parts/753976-relay-telcom-latch-2a-5vdc-pcb-tx2-l2-5v.html
Now if we could just get someone to invent a method overunity energy production...
:S:MarkSCoffman
Mark: Thank you for the information!!! I dont suppose there is an off the shelf Item I could purchase?? As I am a mental midget when it comes to Electronics!!! ;D
Sample Web Link;
http://www.amazon.com/dp/B0002ZSFA0/ref=asc_df_B0002ZSFA01121669?smid=AHF4SYKP09WBH&tag=nextag-ce-mp01-delta-20&linkCode=asn&creative=380341&creativeASIN=B0002ZSFA0
Type "automatic speaker switch" into Google.com
:S:MarkSCoffman
Thanks Mark: I will check it out!!! :)
Why do you want to do this? Why not just use two separate speakers? What kind of equipment are you working with?
Quote from: Dr on May 23, 2010, 11:25:20 AM
...I am trying to hook up two devices to one speaker and I dont want to get bleedoff back into the other system, how do I do this?
http://www.allaboutcircuits.com/vol_2/chpt_9/3.html
In the first page example, DC is isolated from AC on the left side. You might wire two 1:1 transformers as series on the input and parallel on the output? Otherwise an RF mixer could be used?
http://www.tkk.fi/Misc/Electronics/circuits/linemixer.html
Please keep in mind these are suggestions to an unusual question in a sub-discipline of electronics (audio/sound engineering) that I'm not very familiar with.
Wait, the transformer would contribute BEMF/CEMF to the circuit through both coils by core induction, right? Voltage spikes can ring back to the AC/audio source. However, at a 1:1 coil turns ratio, the spikes wouldn't be very big. Whether or not this is objectionable to Dr, is something he'll have to determine.
I
think the mixer might work better, though.
--Lee
Why not simply use a relay?
http://en.wikipedia.org/wiki/Relay
- look up DPDT (DPDT â€" Double Pole Double Throw)
Simple and cheap. ;D
//Egon
@ All: Thank you for all the great replys, What I am attempting to do is use one of the speakers I already have in the ceiling (100) watts, for an intercom system also, so it would do double duty, but I dont want the intercom blasting through the rest of the system, when I am listening to music or watching a movie, I didnt want to add another speaker , because that would mean tearing open the walls that have just been finished. So I think I need something that I can put between the wires and the speaker. yes? no? :)
Yes, it is doable. The solution is simple, but you will need a bit of rewiring and some sort of switch. That one speaker can be connected to both the sound system and the intercom system. The switch will be used as an A/B. A being the sound system, B the intercom. I would imagine the switch being close to the intercom. How that switch is activated could be as easy as a manual switch to something more complex like automatic switching activated by the intercom system in some creative way.
HeairBear: If this AB switch you speak of requires 120 Volts to power it I am still screwed ???
Quote from: Dr on May 24, 2010, 09:53:32 PM
HeairBear: If this AB switch you speak of requires 120 Volts to power it I am still screwed ???
I knife switch can be made to handle 120VAC.
It might look like a kluge, though, but it should work as an A/B switch.
--Lee
Dr.
I think you will have to look at the intercom system. When someone presses the button to talk, there should be some type of relay that is energized. You can use the power connections of this relay to pull in a second relay. The second relay can then be used to switch between speaker. Or maybe easier yet, see what voltage is on the push button and just use that.
To hook up the second relay you would need 2 sets of contacts on it. the common contacts to the speaker. The normally closed to the stereo. The normally open to the intercom. Really shouldn't be that hard.
Hope this helps
Quote from: Dr on May 24, 2010, 09:53:32 PM
HeairBear: If this AB switch you speak of requires 120 Volts to power it I am still screwed ???
A switch doesn't use power really. It just changes the path of the power. Don't confuse a normal on/off switch with an A/B switch. You can use a switch rated for 120V if you need to. Radioshack may carry what you need also, if you don't have any on hand.
You do have alternatives to wiring with wireless solutions too. Is the intercom system already built in? Is this intercom system a one way or two way communication system? If you by any chance have unused phone lines in the home, you may be able to set up a PBX style system for a broader range of options. CableTV and power lines can also be utilized for comm systems if the need arises.
Thanks everyone for your help, I beleive I have it now!!! :)