This is a motor speed controller circuit diagram built based Maxim MAX4295. This with this circuit you will be able to control the speed of motor rotation.

Resistor R1 biases the potentiometer to match the input range of U1. Full counter-clockwise rotation of the pot corresponds to maximum-speed reverse rotation of the motor. Mid-scale on the pot corresponds to motor off, and full clockwise rotation of the pot produces maximum-speed forward rotation in the motor.

Here the wailing alarm circuit diagram:

Component parts List:

R1,R5___________ 4.7K
R2______________ 47K
R3______________ 10K
R4______________ 100K
Rx______________ *see text

C1,C4__________ 100uF/25V, electrolytic
C2,C3__________ 0.01uF (10nF), ceramic
T1_____________ 2N3702 (NTE159, TUP, etc.)
IC1,IC2________ LM/NE555, MC1455P, etc
LS_____________ Loudspeaker

Very easy and simple LED flasher with only three components: a flasher IC, a LED and a electrolytic capacitor.

Component list:

LED1_________Red LED
C1___________100uf/16V
IC1__________LM3909
Battery______1.5V AAA

This is the circuit of LED color fade effect. Just like the name of the circuit, the light intensity of LEDs in this circuit will fade from high  intensity to low intensity and then off.

Here the final result preview:

This is running LEDs circuit which use timer ID NE555N and logic IC 4017N. IC 555 act as a multivibrator and generate frequency to be used for 4017 clock input. R2 is a linear potensiometer to adjust clock frequency and of course the frequency of the blinking LEDs as well.