RCA Jack to RJ14 Adaptor

The sciBot project uses RCA plugs and jacks as the standard connector for sensors, actuators, and accessories. The mBot has four RJ25 jacks, with the jack number written on the top of the mBot. Unfortunately, the mBot does not come with RCA jacks, so we must make an adaptor that connects RCA jacks to a RJ14 plug that can connect to the mBot.

Jack Colour
Shield
Connection
Centre Pin Connection (depends on port)
Port 1 Port 2 Port 3 Port 4
Red Ground +5V +5V +5V +5V
White Ground 11 9 A2 A0

On our adaptor, every red jack has a centre pin with +5V, and an outer shield that is connected to ground.

Every white jack has an outer shield that is connected to ground, and a centre pin that is connected to an Arduino analog or digital pin (A0, A2, 9, or 11).

The RJ14 jack (registered jack 14) has 4 conductors, and was designed to be used for phones that have 2 landlines.

 

 

Materials

Image Quantity Description Manufacturer Vendor
½
7′ RJ14 plug to RJ14 plug cable iCan RJ11-007 Canada Computers CAAC000070
½
6′ RCA stereo extension cable
Chateau 706-72 Dollar Tree
1 3/8″ (9.5 mm) 3:1 adhesive heat shrink, cut to 80 mm Qualtek Q5-3X-3/8-01-QB48IN-25 DigiKey Q53X038B-ND
3 1/8″ (3.2 mm) 3:1 heat shrink, cut to 10 mm Qualtek Q2-F3X-1/8-01-QB48IN-25 DigiKey Q2F3X018B-ND

 

 

Instructions

 

Step 1

Cut the RJ14 cable at least 10 cm from each end. In the picture, the cable has been cut about 20 cm from the end.

The cord in the middle can be saved for another project, but it is not very easy to work with.

Step 2

Cut about 20 mm of the outer insulation from the cable.

Step 3

Orient the cable with the clip up, facing away from you. Cut off the left-most wire.

Note the the colour of the wires may be different from one cable to another.

Step 4

Strip about 2 mm of insulation from each of the 3 wires.

Step 5

Tin the exposed copper wires by heating with a soldering iron and adding a bit of solder.

You may need to add some solder flux, as the cable seems to have some sort of a coating that makes solder not want to stick.

Step 6

Put the big piece of adhesive heat shrink on the RJ14 cable.

Step 7

Cut the RCA extension cable about 15 cm from the jacks. Pull apart the jacks, and strip about 20 mm of insulation from each cut end.

Save the plugs for connecting other sensors and actuators to the sciBot.

Step 8

Strip about 3 mm of insulation from the inner red and white wires.

Step 9

Twist together the bare wires from the RCA cable.

The bare wires are connected to ground. The white wire will be connected to an input/output pin on the Arduino, and the red wire will be connected to 5V.

Step 10

Tin all the exposed copper wires on the RCA cables.

Step 11

Put the short pieces of heat shrink on the RJ14 cable.

Step 12

With the clip up on the RJ14 jack, and the jack pointing upwards, solder the 2 bare wires to the left-most wire. Solder the red wire to the middle wire. Solder the white wires to the right-most wire.

Step 13

 Put the small pieces of heat shrink over the solder joints and heat.

Step 14

Put the large heat shrink over the entire joint, and heat.

Congratulations! You have completed making the adaptor.