And for the sake of completeness, I was surprised to find the 7660 voltage inverter IC chip is still alive and kicking! This is one of those chips like the 555-timer IC chip that has been around forever.
With the 7660 which came as an 8-pin DIP (like the 555), you simply add 2 inexpensive capacitors and you have a positive-to-negative voltage inverter. So put 5V DC in, you get -5V DC out. Put 4.5V DC in, you get -4.5V DC out. It uses so-called charge-pump or switch-capacitor (NO inductors/coils) design and cannot deliver a lot of power but plenty for driving the -5V for the yellow wire output.
I see you can even buy a 3-pin module. Though with the simplicity of the circuit, if soldering up a circuit anyway, this might be one of those unusual situations where you can build it cheaper from parts than you can buy the completed Asia module! 
Again, this addresses the limited interpretation of the OP's question as to how to generate -5V (along with +5V) to drive the yellow-wire. So summarizing:
1. 5V wall-wart with DPDT switch to flip the polarity
2. Half-wave rectified AC with a -5V regulator IC chip
3. Three 1.5V batteries with a switch to flip the polarity
4. Boost step-up switch-mode converter generating +/- outputs
5. DC-DC isolated converter, + of floating DC output tied to common
6. Charge-pump switched-cap voltage inverter
7. Use an actual FasTrack switch
I think we've got this one covered. 
