Schematic & Wiring Diagram

If you need digital volume control, then this circuit will great for you. Just press the button and you will be able to increase and decrease the volume level. This circuit is for 1 kanal only. For stereo audio, you need to build 2 similiar circuit and use push button switch which have double input and double output.

With one single IC, you can build stereo audio amplifier. The circuit is simple, easy made and low in cost. Please take a note that you need headsink on the IC to prevent overheat.

Component List:

R1 C1,C2 C3 C4 C5 C6 U1 MISC

39K 1/4 Watt Resistor 10uf 25V Electrolytic Capacitor 100uf 25V Electrolytic Capacitor 47uf 25V Electrolytic Capacitor 0.1uf 25V Ceramic Capacitor 2200uf 25V Electrolytic Capacitor TDA1554 Two Channel Audio Amp Chip Heatsink For U1, Binding Posts (For Output), RCA Jacks (For Input)

This is sound level meter for your hand made audio device. This circuit will display like spectrum in Jet Audio software.

Supply voltage can be from 3V to 20V. The input is set for audio line voltage (1V peak to peak) and has a max input voltage of 1.3V. To make the circuit use a moving dot display instead of bar graph display, Pin 9 can be should be disconnected from +V.

Parts List.

C1 C2, C3 R1, R3 R2 R4 R5 D1 Q1 LED1-LED10 U1 MISC

2.2uF 25V Electrolytic Capacitor 0.1uF Ceramic Disc Capacitor 1K 1/4W Resistor 10K 1/4W Resistor 100K 1/4W Resistor 1M 1/4W Resistor 1N4001 Silicon Diode BC 558 PNP Transistor Standard LED or LED Array LM3915 Audio Level IC Board, Wire, Socket For U1

This is mono audio amplifier. If you need stereo amplifier, then build 2 similiar circuits. Don't forget to add heatsink on the IC.

Component List:
C1 - 10uf Electrolytic Capacitor
C2 - 470uf Electrolytic Capacitor
C3 - 0.1uF Disc Capacitor
C4 - 2000uf Electrolytic Capacitor 2200uF
R1 - 2.2 Ohm Resistance (Anything Within 10% tolerance)
R3 - 220 Ohm Resistance (Anything Within 10% tolerance)
IC1 - LM383 IC

Components list:

R1………………2K2 1/4W Resistance
R2………………27K 1/4W Resistance
R3R4………….2K2 1/2W Trimmers
R5………………100R 1/4W Resistance
R6………………1K 1/4W Resistance
R7,R8……….. .330R 1/4W Resistance

C1 ………………22µF 25V Electrolytic Capacitance
C2 ………………47pF 63V Polyester or Ceramic Capacitance
C3,C4 …………100µF 50V Electrolytic Capacitance
C5 ………………2200µF 50V Electrolytic Capacitance

Q1 ………………BC550C
Q2 ………………IRF530 or MTP12N10
Q3……………… IRF9530 or MTP12P10

19 watt audio amplifier based on single IC LA4440. I've built this circuit once and give me great audio quality for my hand made audio. Very easy and cheap for beginner.

Here the schematic and specification:

More explanation about water level circuit, please go to this page.

Description:
This circuit will trigger with any fluid with a resistance under 900K between the maximum separation distance of the probes. Let me explain further. The circuit uses a 4050B CMOS hex buffer working on a 5 volt supply.