DIY Isolated Jack

The VRX-1 receiver kit uses a TDA7052 audio amplifier IC, which is a bit different from your run-of-the-mill LM386. Because of its push-pull output, if you use a phones jack, you must isolate it from ground. This isn't something you have to worry about if you use a non-conductive enclosure or if you have an isolated phones jack. However, more often than not, you won't have an isolated jack, and many of the enclosures that we use are metal.

This little hint will allow you to modify a "standard" grounded ring phones jack with a conductive enclosure (such as the 4SQRP Clear Top Tin, like the one I used).

Bill of Materials

  • 3.5 mm phones jack
  • Small length of 3/8" OD (1/4" ID) Polyethylene Tubing
  • 1/4" nylon washer
  • CA glue (optional)

Instructions

Cut off a piece of the 3/8" OD polyethylene tubing approximately 1/16" long (about 1 mm).

Cutting a small piece of the 3/8" OD tubing
Cutting a small piece of the 3/8" OD tubing
Place the small piece of tubing over the phones jack, so that it rests against the body. You may want to glue the tubing to the body of the phones jack.

3/8" OD tubing over jack
3/8" OD tubing over jack
Drill a 3/8" hole in your enclosure to accommodate the tubing, then place your phones jack in the hole so that the 3/8" tubing is centered in the hole. Place the 1/4" nylon washer over the jack from the outside of the enclosure, then use the knurled nut to secure the jack to the enclosure. It's as simple as that!

Isolated jack installed in enclosure
Isolated jack installed in enclosure

5 thoughts on “DIY Isolated Jack”

  1. Hi
    I am wanting to build a VRX 1 RECEIVER, however I can find no mention to the size of the magnet wire for the inductors. would appreciate this info Thanks

  2. It's nothing too critical. AWG 28 was used here, but something close should also work.

    73,
    Jason

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