With only 4 components you can experiment with wireless transmission of electric energy. This system exploits the resonant inductive coupling between two coils to transmit energy between them.
Slider 2732 (you should check his channel, he has great experiments on wireless systems and other subjects www.youtube.com/user/slider2732
) makes the following suggestions:
Any NPN or PNP small signal transistor can be used. For PNP, simply swap the battery connections over. Best to try, include 2N2222A, S9014, C1815, C1213, MPSA06. For PNP, 2SA733 and upward.
For overheating troubles, make sure to have 12+ turns and/or add 100ohm resistor in series to a power wire input, or a similar resistor to the Base.
Adding a 1N4148 diode on the other power input will also drastically reduce heat and current.
To run at higher voltages than 1.5V, add a 5K variable resistor to the Base.
Use 12 turns and above for reliable operation, around 26AWG wire works best.
Small ceramic capacitors can be added to receiving coils for improved efficiency. 0.001 range ('102' as written on popular types). Receiving coils can be various and need not match the transmitting coil...such as a ferrite round choke with LED on top, 1/2 diameter coil or pancake coil.