Im not posting a book here about it but heres a bit on transistors

[b]A transistor is an efficient energy saving version of a relay. It acts as an automatic switch when positive voltage is applied to the base, or a signal, which is voltage. Lets say its a BC547b or 2n2222 equivalent. If the flat side of the transistor is facing you, then the left pin is the[ collector. The middle pin is the base. The right pin is the emitter. The collector should be wired to positive on a source such as the power source. The base should be wired to a signal source, such as pin 3 on a 555 timer, and the emitter wired to the positive terminal of an led or motor. The negative terminal of the led or motor is grounded to negative on the power source, along with negative of the signal giving circuit. If these 2 negatives arent integrated or closed, it wont work. The collector can use its source from positive within the entire circuit too, if the supply is powerful enough and the device turned on by transistor doesnt drain too much current to interfere with the base signal. A single bc547 will likely not be sufficient for a size 160 or 260 motor. At least 3 transistors will be required in parallel for sufficient enough current to power the motor. 7 transistors is a safe bet. The more transistors used in parallel, the longer the lifespan when using such high drain devices. A single power transistor such as the tip120 can also be used with a heatsink however. The switch or gate voltage is usually 10v to function. And that can be a problem in say a 3 or 6 volt circuit. A single bc547 can be used to turn on up to 4 leds, beings their rating is 100ma, without frying it. Ive fried many transistors and they smoke followed by blowing a hole in themselves. 0/b]