The Rain Alarm circuit applies 4 NAND gates of the 4011 IC. In each individual oscillator, while a single gate is configured a straightforward inverter, some other has one input that will act as a control input. Oscillator action is inhibited if this enter is held low. The first oscillator (IC1a and also IC2b) has this kind of input tied low through a high value resistor (R1) which acts as a sensitivity control. Thus this oscillator will be disabled until the control input is taken high. Any moisture bridging the sensor track will so enable the output which is a square wave at about 10 Hz. This in turn will gate on and off the 500 Hz oscillator formed by IC1c and IC1d. This latter oscillator drives the loudspeaker via R6, the Darlington pair formed by Q1 and Q2, and resistor R7.

This simple LED circuit makes the  LED effect as in Knight Rider LED car. The chain of nine high-brightness LEDs are constantly running from left to right and from right to left. You can use red LEDs, and to attract additional attention to the front – white LEDs.

All types of CMOS chips are used, so it can be powered by a 9V battery PP3, which is enough for a very long time, since the current consumption of the Knight Rider LED circuit quite small.

How its work :
To IC4, C1, R1 and R2 made ​​a pulse generator, which come at terminals 14 of both counters IC2 and IC3.
IC1 – this is a trigger that is used to switch counters IC2 IC3 pin or permit 13.
IC7a valve determines which of the counters have appeared “1″ at the output of Q9 (output 11), ie, which of the counters count up to a maximum value.
IC5, IC6 and protect IC7a output of the counter IC2 and IC3, using the gates, “OR” that feed the anodes of LEDs 1 … 9.

Parts list :
R1,R2 : 10 k ¼
R3 : 470 ohm ¼
C1 : 6.8 uF/16v
IC1 : 4027 one flip-flop
IC2 and IC3 : 4017 two decimal counter
IC4 : 555 timer
IC5, IC6 and IC7 : 4071 three chips gates, “OR”
9 V battery size
high-brightness LEDs
Housing for Knight Rider LED circuit

Based on the book “Gather yourself” no. 2, 2004.

Synthesizer assembly
Before assembling the board review the recommendations that are given at the beginning of this book. To avoid failure, try to observe generally accepted rules of assembly. List of components within the set of NM5101, presented below :

Parts List of NM5101 set

In accordance with Fig. 3 install and weld components on the board. DA1 chip is installed in accordance with Fig. 4 ( Synthesizer lighting effects part 3 ).
After installation check the quality of the ration and proper installation elements. Recheck charge for lack of short-circuits and breaks tracks.

This device would be interesting for students: introduction to the basics of electronics, allowing you to experience the assembly and adjustment of modern electronic devices. Synthesizer will be used for fan of light effects as a festive illumination, or a tutorial on microprocessor technology and programming.
This device requires a voltage 9-25V and current around 50mA.

Description of this Synthesizer

Fig. 1 and Fig. 2 on the Synthesizer lighting effects part 2 shows the assembly of synthesizer boards and electric circuit.

Synthesizer is based on a microcontroller from Atmel (DD1). Power supply of the microcontroller obtained from the IC regulator DA1.
Elements of CI, C2, ZQ1 set the operating frequency of the internal oscillator of the microcontroller. Resistors R1 … R6, R8 – used for current limiting. SW1 button is a consistent choice of animated images. The basic version of the proposed microcontroller 12 stitched images.

This is how simple lie detector work : The circuit uses an oscillator that has a frequency based on C1, R2, and skin resistance at the touch pad. Because C1 and R2 value is fixed, only the skin resistance at the touch pad that can change the tone oscillator. To maintain oscillation, the C1 provides some output from Q2 back to the input of Q1 through R1.

Q1 is NPN type transistor and Q2 is PNP type transistor. Output Q2 is given to a small speaker.
Part List :

• C1 = 10 nF
• R1 = 4K7 ohm
• R2 = 82 kohm
• Q1 = 2N3904
• Q2 = 2N3906

• C1 = 68nF
• R1 = 4K7
• R2 = 10K
• R3 = 330
• U1 = 555
• U2 = 7493
• U3 = 74154
• D1-D16 = LED

This Running LED circuit will need 5 Volt power supply.

Parts list:
R1, R7 = 470Ω
R2 = 1kΩ
R3 = 68Ω
R4, R6 = 56kΩ
R5 = 47kΩ
R8, R9 = 10kΩ
VR1 = 200Ω Potentiometer
C1, C2, C3 =10μF/16V
C4, C5 = 0.02μF (20nF)
C6 = 100μF/16V
Q1, Q2 = 2N3904
IC1 = 555 or 1455
LED1, LED2 = LED

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.