A circuit, includes a first node, a positive voltage generator electrically connected to the first node, a negative voltage generator electrically connected to the first node in parallel with the positive voltage generator, a second node, an electrical connector electrically connecting the first node to the second node, a first light emitting diode (LED) electrically intermediate the second node and ground, and a second LED electrically intermediate the second node and ground in parallel with the first LED. The first LED is configured to activate based on the negative voltage generator supplying a negative voltage to the second node via the first node. The second LED is configured to activate based on the positive voltage generator supplying a positive voltage to the second node via the first node.