Neck loop question

Assistive Listening Devices
#1

Has anyone made their own neck loop? I’ve looked on this site but can’t find any information, sorry if I just missed it.

I know basically what needs to be done but finding the resources for the parts hasn’t been all that easy, especially a lightweight “case”. The people with whom I’ve spoken who have made their own end up with very workable devices but they are huge, bulky (using plastic tubing with coils within the tubing) and not practical for the average person. I know it can be done relatively inexpensively but I could use some help finding the best way to go about finding the combination of resources.
Any suggestions would be appreciated.

Thanks

#2

Hi Michelle.
I do quite a bit of DIY, but would not tackle a neck loop as the light weight cable usually vanishes with the heat of a soldering iron. They can be purchased separately here in the UK, although they normally come with a listening device.

Are they not available in the US?

#3

Thanks for the reply, John. Yes, neckloops are readily available here, I have a few myself. I’m asking because a member of our Hearing Loss Association chapter used to make very low cost NLs, about 1/3 of the least expensive non powered NLs. Unfortunately, he passed away and since I’m on our technology committee I was asked if I wanted to look into making them.

The problem is no one knows where he obtained his supplies. In addition they were not very robust. My husband is a scientist who has a great deal of electrical experience (he just put together a phone flashing system for me which fortunately does not produce spurious results due to line interference) and knows it could be done easily provided the components could be obtained at a relatively low cost.

I have a source for mini transformers, strain reliefs and wire. I’m still looking for an appropriate enclosure box and some odds and ends. I don’t know if I’ll ever tackle the job but it may be fun at least for a short term project.

We do have some folks in our chapter who made their own NLs but they are definitely not appropriate for the average person. They are quite powerful but very bulky, moderately heavy and not something that would make a positive fashion statement!

#4

These any good to you?

Here

If you Google ‘Induction Neckloop’ in your area you should get some local shopping results too.

#5

Thanks for the links. I have several neckloops myself and don’t need another. I was looking for a way to make them…

#6

I found a couple of DIY pages and I will post the content here. This first one is easy, but doesn’t have many “turns” so I don’t know how powerful it would be.

"I use a neckloop to listen to an MP3 player while at work (actually, I listen to the FM radio on it more than the music)
Points I’ve found:
1: The loop contains a couple of resistors that sum the two audio channels into one. (i.e. you wont get stereo from a neckloop)
2: Compared to the ‘normal’ ear buds these players are designed to be used with, a neckloop needs a lot more audio level applied to it, so the battery runs out faster.
3: Being able to listen to just the radio or music - no background noise at all - while at work is great! (You may also be able to listen to both the T-coil and normal sounds, if the aid has provision for it). You dont need to pay that for a neckloop, you can make your own.

Parts:
A meter or so of flexible telephone cord (more conductors the better),
3.5 stereo plug,
(2) 1/8th watt small-value resistors (I use 12 ohms).

Method:
Cut a length of the cable long enough to go over the head, plus a bit. Note that making it longer is no advantage, it would just place the loop further away from the t-coil in the aid.
Strip and tin all wires in both ends.
Connect the wires to form a coil, i.e. if it has 4 conductors of red, green, white & blue, then you might connect:
Red (at one end) to green.
Connect other end of green to white.
Connect other end of white to blue
You would now have one red and one blue end left over.
Connect one of these to the common conductor of the plug.
Solder a resistor to each of the tip and ring conductors of the plug.
Solder the other ends of the resistors together and connect to the other
wire.

Naturally, you’ll want to insulate all theses connections from each other with heat-shrink tube.

Realizing you have left off the cover for the plug, you now de-solder all the above and feed the wires through it then re-solder [grin] Plug in and test."

#7

Here is another discussion on a Yahoo forum. I too have noticed people using an LM386 IC headphone amp chip with a small series resistance.

The battery is a standard 9V alkaline. My neckloop: I meant to say 30 inches
circumference… not diameter.

How long the battery lasts? It is hard to say because it depends on how much I
use it. I usually go one to two months unless I forget to turn it off. At
conventions, I use it constantly, but otherwise I just use it now and then. One
battery will usually last for the entire convention.

I have another version of the ALD that runs on 6V and for that I use AA size
batteries. The LM386 gives more power with higher voltages, but it seems to work
OK on 6V. There are some new ICs that I would like to explore, but they use the
surface mount packages and that is hard to solder! One thought is to use a class
D amp which is a digital PWM technique. They deliver lots of power with little
heat loss so the new modern loop drivers (current drive) may use that
technology. The output transistor is on solid or off solid, but is pulsed at a
rate that simulates analog audio.

Ron

— In Loops_and_Telecoils@yahoogroups.com, John Woodgate <jmw@…> wrote:
>
> In message <iq20ou+5rh0@…>, dated Fri, 6 May 2011, ranarium
> <Ron.Vickery@…> writes:
>
> >My ALD consists of an amp and neckloop integrated into one package with
> >no dangling cords. The loop driver is a LM386, powered by a 9V battery
> >which gives about 300 miliwatts of power.
>
> What sort of battery is that and how long does it last?
>
> >The neckloop is fifty feet of 30 G wire in a loop about 30 inches in
> >diameter.
>
> That’s quite a big diameter for a neck loop; 10 inches seems common. Six
> turns sounds plausible.

#8

And finally here is another “passive” one. I haven’t made any myself yet, but since they sell for $50 and up, I’m keen to try.

A non-amplified neck-loop (needing no battery) would be an EASY DIY
project but for one thing - covering the loop with some soft flexible
material. No problem, maybe, if you can find a skilled needle-worker.

You need a ‘former’ about 250 mm diameter, around which you wind 30 to
40 turns of enamel-insulated ‘magnet wire’, Ideally, the wire should be
a ‘bunch’ of 7 strands of VERY fine wire (38 AWG), but this is difficult
to obtain in small quantities. Other types of wire might be suitable but
the result must be flexible, not too bulky and the wire must not break
too readily. Maybe 28 AWG will meet with your approval.

Take the loop off the former, tie some thread round it in a number of
places to hold it together and cover it with a strip of fabric stitched
to form a tube. Pu the seam where it will not irritate.

Trap the loop in a small plastic box where the wire ends come out and
connect them to a thin twin-wire cable. Connect one of the wires to the
sleeve of a 3.5 mm jack plug. Measure the resistance of the loop and
connect between the other wire and the tip of the plug a miniature
resistor to bring the total resistance to between 16 and 32 ohms. The
resistor may be put in the body of the jack plug or in the plastic box.
Less resistance = more sensitivity, but some sources may not work well
with a 16 ohm load. Many will accept it. More turns = more sensitivity.