adding an exterior speaker to a security camera

[The Original Ralph]

i've got a question for someone electrically or electronically literate - i have a basic "fred flintstone" literacy from working on cars years ago

i'm connecting this "stereo" laptop speaker set to a hikvision outdoor camera, images below

the green plug on the camera only has two connection slots for audio marked "GND" and "A" for audio, per the manual. The other two are for alarm, ie PIR, I/O, so i assume it's only meant to generate Mono output, which is understandable.

below is the volume control switch between the USB 2.0 plug & 3.5mm male jack and the speakers

on the right side of the switch, are the R & L speaker connections (top right you can see R+ & R-, and you can barely see the L+ & L- at the bottom right

on the left side there's a black & red pair of leads that are coming from the USB connector which i assume are the power leads. Also on the left side of the switch are a green lead, yellow lead and white lead which come from the 3.5mm male jack. I've assumed the green lead is the GND lead and the other two are L & R

here's the question. When i connect the speakers to my computer, i get a small windows menu opening that allows me to test the speakers, L and R separately, and when i test them i get sound only from the appropriate speaker, ie L or R

But when i connect only one of the L or R leads, i get sound out of BOTH speakers, it doesn't matter whether i connect the yellow or white to the camera. I've also connected both the yellow and white to the "A" port on the camera's connector, same result which i would expect

how can i be getting that result, ie sound from both speakers with only one side connected. I was hoping to disconnect ie cut, one speaker out to better fit the laptop speaker inside the old nutone intercom box at the entrance way, but when i do, i loose all sound??? BTW, that laptop speaker set splits into two separate speaker housings

any help appreciated

 

[mwryder55]

It has been far too long since I did anything with electronics but I will throw out a couple of ideas that might help. As far as both speakers working when only one lead is connected the computer might be thinking that you have a monaural output and place output on both lines. As far as getting it to work with only one speaker what happens if you put a load, i.e. a resistor, in place of the missing speaker? Maybe the computer needs some kind of load on the line(s) to think that there is anything to output to.

 

[The Original Ralph]

THE jack is a stereo jack - and this is occurring without the computer in the circuit - the output (monaural) is coming from the camera to the volume switch you see, as i stated earlier, and that usb connector is coming off a wall wart with a usb port on it, so that's where it's getting it's power

as to putting something, like a resistor in place of the 2nd speaker, i'm not knowledgeable enough to know what value resistor etc to use. They'll both fit in the nutone box, i was just hoping to keep the 2nd speaker as a replacement for when / if the first speaker goes bad.

On the up side, it's crazy how much volume i get from that laptop speacker setup - total outlay including the wall wart was $24 vs $480 for the lowest priced exterior amplified speaker

 

[mwryder55]

I would start with a resistor with about the same resistance as the speakers, i.e. 4 ohms if they are 4 ohm speakers, and the same or greater wattage and see what happens.

 

[The Original Ralph]

THANKS

 

[The Original Ralph]

just putting this up for anyone else googling "exterior speaker for security cameras)

a buddy, retired electrical engineer, said, that without having the amplification board in hand to test, he can't be absolutely sure but it's possible the IC chip may be coded to piping mono signals to both speakers, and that the engineer that designed this laptop speaker set designed to work with both speakers connected

it's working fine, good volume and remarkably clear comm, so i've trimmed the plastic clamping ears off the speaker cabinets and both fit into the old nutone intercom cabinet. I ran the USB power connector on the laptop speaker set to a decent quality wall wart (Ankers) plugged into an extension cable that runs across the attic and down to my UPS battery backup - so the system will still work in a power outage. And in case, i'd tried some of the el cheapo wall warts - two different ones and both gave me a bad hum over the spearkers, one of them "hummed" even when i wasn't using the intercom function.

I've also waterproofed the amplication PCB board with some "conformal coating" he recommended - looks like it's just polyurethane in a spray can

in case that helps someone else