Cordless headphones revival

So, who here hates bluetooth audio? Now who knows what it is? Good, all the same hands stayed up.  I have an alternative to this crappy option: go old school!

Ok, now I picked up these headphones some time in the past, probably at a garage sale.  They are, specifically, Optimus 33-1145 900 Mhz headphones, FCC ID: CLV-A900T.   Originally these headphones had a Ni-Cd pack that allowed them to be re-charged form the base station, it was long dead.  So, to get these operational I need a power adapter, and a new battery for the headset.  Let’s start with problem 2 first, the battery.  The battery supplied 3 volts, was triangular in shape, and had a charger port on the side of the headphones where it could plug into the base.  I really wanted a cheap solution, so I took the best of my 2xAA battery holders at the time (from an old AV receiver IIRC) and glued it right on the outside.  I removed the charging port and re-located the power LED that the battery covered up now.

the on/charge switch is now the on/off switch

Good, now the headset is converted to replaceable batteries (or, you know rechargeable AAs or whatnot) let’s look at the base station.

with mods applied

Here is the back, it has a DC power jack originally spec’d for 18v, a 3.5mm headphone jack for charging the original battery, a volume control, audio in in a less than useful format for my purposes, and a frequency fine tuning knob.  Now let’s look inside and see what I did.

So, right away two things should stick out: that yellow wire bypassing a voltage regulator and that charging jack doesn’t look stock.  The charging jack was removed, flipped over, and glued back down to be a 3.5mm audio in port (it’s wired in parallel with the other audio jacks on the bottom [with shielded cable even!]).  The regulator was there because the original power brick was apparently very unstable and needed to be cleaned up for audio use.  I did this so long ago I can’t remember why I spec’d the new power supply at 16v, but I trust myself because it’s working.  So now we have a working headphone set, cool! but what other features do we want?

Another headphone jack of course! I could have done this right and used a switched jack, but that wouldn’t allow me to tether a friend to me so we could both listen together.  My motivation for this was mainly that now I can play music (I mainly listen to audio books, but I’m strange like that), walk around the house, and when I get to a place with a set of powered speakers I can settle in, plug the headphones into the speakers and keep listening rather than have to queue up the track on whatever computer was nearby and hooked up to those speakers.  So there you go, replaced a toasted voltage regulator, replaced rechargeable batteries with replaceable, and even added a new feature.  I think this one worked out pretty well.  Full album is here.

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