Specifications

2000
Contents
JANUARY 2000
CONSTRUCTION PROJECTS
1) MICROPROCESSOR-CONTROLLED TRANSISTOR LEAD IDENTIFIER --------------------------------------------- 1
2) CONVERSION OF AUDIO CD PLAYER TO VIDEO CD PLAYER  I ----------------------------------------------- 9
CIRCUIT IDEAS
1) MULTIPURPOSE CIRCUIT FOR TELEPHONES ------------------------------------------------------------------------- 13
2) SIMPLE CODE LOCK -------------------------------------------------------------------------------------------------------- 13
3) AUTOMATIC BATHROOM LIGHT----------------------------------------------------------------------------------------14
4) SMART FLUID LEVEL INDICATOR --------------------------------------------------------------------------------------- 15
5) AUTOMATIC SCHOOL BELL SYSTEM ----------------------------------------------------------------------------------16
6) DESIGNING AN RF PROBE ------------------------------------------------------------------------------------------------18
FEBRUARY 2000
CONSTRUCTION PROJECTS
1) PC BASED SPEED MONITORING SYSTEM ---------------------------------------------------------------------------- 19
2) STEREO CASSETTE PLAYER ----------------------------------------------------------------------------------------------- 24
CIRCUIT IDEAS
1) BASS AND TREBLE FOR STEREO SYSTEM ----------------------------------------------------------------------------29
2) PROTECTION FOR YOUR ELECTRICAL APPLIANCES ---------------------------------------------------------------- 29
3) DIGITAL WATER LEVEL METER ------------------------------------------------------------------------------------------ 30
4) UNIVERSAL HIGH-RESISTANCE VOLTMETER ------------------------------------------------------------------------- 31
5) TRIAC/TRANSISTOR CHECKER ------------------------------------------------------------------------------------------- 32
6) A NOVEL METHOD OF FREQUENCY VARIATION USING 555 --------------------------------------------------- 33
MARCH 2000
CONSTRUCTION PROJECTS
1) RESONANCE TYPE L-C METER ------------------------------------------------------------------------------------------- 34
2) ELECTROLYSIS-PROOF COMPLETE WATER-LEVEL SOLUTION --------------------------------------------------- 38
CIRCUIT IDEAS
1) PENDULUM DISPLAY ------------------------------------------------------------------------------------------------------- 42
2) AUDIO LEVEL INDICATOR ------------------------------------------------------------------------------------------------ 42
3) CLEVER RAIN-ALARM ------------------------------------------------------------------------------------------------------ 44
4) LASER CONTROLLED ON/OFF SWITCH -------------------------------------------------------------------------------- 45
5) TELEPHONE CONVERSATION RECORDER ---------------------------------------------------------------------------- 45
6) SIMPLE AND ECONOMIC SINGLE- PHASING PREVENTOR -------------------------------------------------------46
APRIL 2000
CONSTRUCTION PROJECTS
1) SMART CLAP SWITCH ----------------------------------------------------------------------------------------------------- 48
2) ELECTRONIC VOTING MACHINE ---------------------------------------------------------------------------------------- 51
CIRCUIT IDEAS
1) WATER-TANK LEVEL METER ---------------------------------------------------------------------------------------------57
2) PHONE BROADCASTER ---------------------------------------------------------------------------------------------------- 58
3) TELEPHONE CALL METER USING CALCULATOR AND COB ------------------------------------------------------ 59
4) SIMPLE ELECTRONIC CODE LOCK -------------------------------------------------------------------------------------- 60
5) LATCH-UP ALARM USING OPTO-COUPLER -------------------------------------------------------------------------- 61
6) MINI VOICE-PROCESSOR ------------------------------------------------------------------------------------------------- 61