ELECTRONICSPROJECTSVOL. 21

Section A: Construction Projects

1. Conversion of Audio CD Player to Video CD Player — I……………………………………….. 13
2. Conversion of Audio CD Player to Video CD Player — II………………………………………. 16
3. Microprocessor-Controlled Transistor Lead Identifier…………………………………………….. 19
4. PC-Based Speed Monitoring System ……………………………………………………………………. 28
5. Stereo Cassette Player ………………………………………………………………………………………… 33
6. Resonance Type L-C Meter…………………………………………………………………………………. 39
7. Electrolysis-Proof Complete Water-Level Solution ………………………………………………… 44
8. Smart Clap Switch……………………………………………………………………………………………… 49
9. Electronic Voting Machine ………………………………………………………………………………….. 52
10. Digital Number Shooting Game…………………………………………………………………………… 58
11. PC Interfaced Audio Playback Device: M-Player…………………………………………………… 62
12. Portable Ozone Generator …………………………………………………………………………………… 69
13. Conference Timer………………………………………………………………………………………………. 77
14. Build Your Own C-band Satellite TV Receiver ……………………………………………………… 80
15. EPROM-Based Programmable Number Lock ……………………………………………………….. 87
16. Display Schemes for Indian Languages (Hardware and Software)……………………………. 90
17. 8085 μP-Kit Based Simple IC Tester ……………………………………………………………………. 107
18. Digital Code Lock ……………………………………………………………………………………………… 111
19. MOSFET-Based 50Hz UPS-Cum-EPS …………………………………………………………………. 115
20. R-2R D/A Converter-Based Function Generator Using PIC16C84 Microcontroller…… 124
21. PC-to-PC Communication Using InfraRed/Laser Beam………………………………………….. 130
22. Multi-Effect Chaser Lights Using 8051 Microcontroller…………………………………………. 136
23. Electronic Bell System ………………………………………………………………………………………. 140
24. Simple Telephone Recording/Answering Machine…………………………………………………. 144

Section B: Circuit Ideas

1. Multipurpose Circuit for Telephones…………………………………………………………………….. 149
2. Simple Code Lock ……………………………………………………………………………………………… 149
3. Automatic Bathroom Light………………………………………………………………………………….. 150
4. Smart Fluid Level Indicator…………………………………………………………………………………. 151
5. Automatic School Bell System…………………………………………………………………………….. 152

CONTENTS

6. Designing An RF Probe………………………………………………………………………………………. 154
7. Bass and Treble for Stereo System……………………………………………………………………….. 154
8. Protection for Your Electrical Appliances……………………………………………………………… 155
9. Digital Water Level Meter…………………………………………………………………………………… 156
10. Universal High-Resistance Voltmeter …………………………………………………………………… 157
11. Triac/Transistor Checker …………………………………………………………………………………….. 158
12. A Novel Method of Frequency Variation Using 555……………………………………………….. 159
13. Pendulum Display ……………………………………………………………………………………………… 160
14. Audio Level Indicator…………………………………………………………………………………………. 160
15. Clever Rain-Alarm …………………………………………………………………………………………….. 162
16. Laser Controlled On/Off Switch ………………………………………………………………………….. 163
17. Telephone Conversation Recorder ……………………………………………………………………….. 163
18. Simple and Economic Single-Phasing Preventor……………………………………………………. 164
19. Water-Tank Level Meter……………………………………………………………………………………… 165
20. Phone Broadcaster……………………………………………………………………………………………… 167
21. Telephone Call meter Using Calculator and COB ………………………………………………….. 167
22. Simple Electronic Code Lock………………………………………………………………………………. 169
23. Mini Voice-Processor …………………………………………………………………………………………. 170
24. Latch-up Alarm Using Opto-Coupler……………………………………………………………………. 171
25. Stepper Motor Driver …………………………………………………………………………………………. 171
26. Electronic Digital Tachometer……………………………………………………………………………… 172
27. Light-Operated Light Switch……………………………………………………………………………….. 174
28. Precision Digital AC Power Controller…………………………………………………………………. 174
29. Luggage Security System……………………………………………………………………………………. 175
30. Add-On Stereo Channel Selector Cum Level Indicator…………………………………………… 176
31. Water Temperature Controller……………………………………………………………………………… 177
32. Emergency Light ……………………………………………………………………………………………….. 178
33. Parallel Telephone With Secrecy………………………………………………………………………….. 180
34. Single Doorbell for Two Doors……………………………………………………………………………. 181
35. Powerful Pest Repeller……………………………………………………………………………………….. 181
36. Power-Supply Failure Alarm……………………………………………………………………………….. 182
37. Stopwatch Using COB and Calculator………………………………………………………………….. 182
38. Dial a Voltage ……………………………………………………………………………………………………. 183
39. Electronic Dancing Peacock………………………………………………………………………………… 184
40. Inverter Overload Protector with Delayed Auto Reset…………………………………………….. 185
41. Telephone Line Based Audio Muting and Light-on circuit………………………………………. 186
42. Low-Cost PCO Billing Meter………………………………………………………………………………. 187
43. Automatic Muting Circuit For Audio Systems……………………………………………………….. 188
44. 2-Line Intercom-Cum-Telephone Line Changeover Circuit …………………………………….. 189
45. Guard for Refrigerators and Air-Conditioners ……………………………………………………….. 190
46. Radio-Band-Position Display………………………………………………………………………………. 191
47. Binary to Dotmatrix Display Decoder/Driver………………………………………………………… 192
48. Automatic Speed-Controller for Fans and Coolers…………………………………………………. 194
49. Blown Fuse Indicator …………………………………………………………………………………………. 195
50. Over-/Under-Voltage Cut-Off With On-Time Delay……………………………………………….. 196
51. One Button for Step, Run, and Halt Commands…………………………………………………….. 197
52. Simple Switch Mode Power Supply……………………………………………………………………… 198
53. Toilet Indicator ………………………………………………………………………………………………….. 199
54. Feather-Touch Switches for Mains……………………………………………………………………….. 200
55. Digital Fan Regulator…………………………………………………………………………………………. 201
56. Telephone Ringer Using Timer ICs ……………………………………………………………………… 203
57. Automatic Battery Charger………………………………………………………………………………….. 203
58. Temperature Measurement Instrument………………………………………………………………….. 205
59. Voice Bell …………………………………………………………………………………………………………. 206
60. Moving Curtain Display……………………………………………………………………………………… 207
61. Proximity Detector …………………………………………………………………………………………….. 208
62. Multichannel Control Using Soft Switches……………………………………………………………. 209
63. An Exclusive Sinewave Generator……………………………………………………………………….. 210
64. TTL Three-State Logic Probe………………………………………………………………………………. 211
65. AM DSB Transmitter for Hams …………………………………………………………………………… 212
66. Ground Conductivity Measurement ……………………………………………………………………… 213
67. Stepper Motor Control via Parallel Port………………………………………………………………… 214