converting 12v to 9v

[Bob Hoffman]

I have an ANR headset that have the ANR portion powered by a 9v battery pack,the cord has a little plug that plugs into the battery case.

Now,bearing in mind that I'm not an electrican,what do I need to do to convert the aircraft 12v power to a 9v plug so I can eliminate the battery pack.

I was thinking of putting a receptacle next to the head set jacks.

I have a "tilt" so I'm putting the jacks in the rollbar support where the rear window is.

A suggested sorce for the required parts would also be appreciated.

Thanks
Bob

[Mel]

Bob,
Go down to the aviation section of your nearest Radio Shack and get a 9v converter. Hard wire this in and put a jack next to your headset jacks. I tied mine in to the avionics master so it turns off the headsets when I turn off the AV master.

[nucleus]

call up your headset manufacturer and get a lemo conversion kit. About $150 for the Bose.

Hans

[Mike S]

Agree, contact mfg.

My Headsets Inc. units have a built in power option, regulated power that will drive 2 headsets.

Less than $40

[roee]

A 9V linear regulator would be a very simple solution. The LM7809 is a 3-pin device that will take anywhere from about 11V to 35V input and give you a clean 9V output up to about 1A in a TO-220 package. The LM7809 has been around since the dinosaurs walked the earth, it is made by multiple manufacturers, should cost less than a buck, is available from online distributors such as Digikey, and probably even at Radio Shack (Mel, is that what you used?).

[deene]

Yep, the 7809 works fine (7810 is actually better as a 9.6v supply) and with two additional caps (0.1 and 1uf), you've got a $3 solution. Solder the caps together directly on the regulator with pigtail leads and shrink wrap the whole thing.

And at the low power levels needed, the linear regulator is quiet and works very well.

I have built many of these for friends and their ANR headsets as a ships power unit. Order the right mini jack for the deal and install in less than one hour.

If anyone wants to not deal with the solder, I'll send you one built for $20 ($30 with the jack which you need to specify for your headset).

[Bob Hoffman]

Thank you all for your responses.
Deene -- what are caps (0.1 & 1uf) ??? what do they do ?
Thanks again
Bob
P.S. Is a 9V battery 9V or 9.6V ? (do I need the LM7809 or the LM7810)?

[roee]

Originally Posted by Bob Hoffman

Deene -- what are caps (0.1 & 1uf) ??? what do they do ?

Capacitors. Adding input and output capacitors as Deene suggests helps clean up the signal even further, and in some cases is necessary for stability of the regulator. In this application you could probably do ok without them, but adding them is certainly a good idea.

See Figure 7 in the LM7809 datasheet: http://www.fairchildsemi.com/ds/LM/LM7809.pdf

Bob, if you're not electronically inclined, consider taking Deene up on his offer to sell you a complete circuit.

Originally Posted by Bob Hoffman

P.S. Is a 9V battery 9V or 9.6V ? (do I need the LM7809 or the LM7810)?

What type of battery is it exactly? An alkaline 9V battery really is nominally approximately 9V (six cells, ~1.5V per cell). A rechargeable battery pack composed of eight NiCd or NiMH cells (~1.2V each) would be more like 9.6V nominally. In either case, there will be quite a bit of variation in battery voltage depending on load and decreasing as the battery discharges. Battery powered devices are therefore generally designed to accommodate a wide variation in input voltage. What really matters is what is the input voltage range that your headset requires? Anywhere within that range should be fine.

[Ken9]

I am wiring this elcheapo 9v power supply for my Headsets Inc. ANR. Can anyone tell me where to get the correct mini jacks for the system?

[Mel]

The aviation aisle at Radio Shack. Assuming that it's a standard 1/8" jack.