1. DC-DC converter 1
2. Periodically On-Off Mosquito Repellent 2
3. IR sensors (infrared LEDs) to make an object-detection circuit 3
4. Simple Key-Operated Gate Locking System 4
5. Mains Box Heat Monitor 5
6. Faulty Car Indicator Alarm 5
7. Tachometer 6
8. 1W LED For Automotive Applications 7
9. Play With Robotic Eye (IR Sensor) 7
10. Timer From Old Quartz Clock 8
11. Keep Away Ni-Cd From Memory Effect 8
12. Crystal AM Transmitter 9
13. Programmable Electronic Dice 9
14. Software of the Month: Resistor Calculator 1.0.6 10
15. IR-Controlled Water Supply 11
16. PC-Based Candle Igniter 11
17. Noise Meter 11
18. Handy Tester 12
19. Linear Timer For General Use 13
20. Strain Meter 13
21. Digital Soil Moisture Tester 14
22. Over-Heating Indicator for Water Pipe 14
23. Simple Key-hole Lighting Device 15
24. Timer with Musical Alarm 15
25. Automatic Water Pump Controller 16
26. Water Pump Controller 16
27. Ball Speed Checker 17
28. Halogen lamp Saver For Bikes 17
29. Night Vision Enhancer 18
30. Triple-Mode Tone Generator 19
31. Soldering Iron Temperature Controller 20
32. Mains Failure/Resumption Alarm 21
33. Multipurpose White-LED Light 21
34. IR-Based light Control 21
35. Sequential Device Control using TV Remote Control 22
36. Make your own Electric Bug Zapper 22
37. Twilight Lamp Blinker 23
38. Emergency Photo Lamp 23
39. Sound-Operated Intruder Alarm 24
40. Electronic Street Light Switch 25
41. Little Power-Hila Vinegar Battery to power a calculator ! 25
42. Standby Power-Loss Preventer 26
43. Hum-Sensitive Touch Alarm 27
44. Touch Alarm 28
45. Versatile LED Display 28
46. HDD Selector Switch 29
47. Multiutility flash light 29
48. Long-range Burglar Alarm Using Laser Torch 30
49. Twi-light using white LEDs 30
50. PC TIMER 31
51. Infrared Object Counter 31
52. Pushbutton Control For Single-Phase Appliances 32
53. Timer for Mosquito Destroyer 32
54. Automatic Soldering Iron Switch 33
55. White LED Light Probe for Inspection 33
56. Pencell Charge Indicator 34
57. Doorbell-controlled Security Switch 34
58. PC-Based Timer 35
59. Power Resumption Alarm and Low-Voltage Protector 35
60. Miser Flash 36
61. Room Sound Monitor 36
62. Battery-Low Indicator 37
63. Micro Inverter 38
64. Security System Switcher 39
65. Another Water Pump Controller circuit 39
66. Soldering Iron Tip preserver 40
67. Automatic Washbasin Tap Controller 41
68. Over-Speed Indicator 41
69. Speed Checker for Highways 42
70. 1.5W Power Amplifier 42
71. Simple Stereo Level Indicator 42
72. FM Bug 44
73. Calling Bell Using an Intercom 44
74. Digital Frequency Comparator 45
75. Bhajan and Mantra Chanting amplifier 46
76. Cable Tester 47
77. Automatic 3-Phase Induction Motor Starter 48
78. Wireless Stepper Motor Controllers 49
79. Manual EPROM Programmer 50
80. Noise-Muting FM Receiver 50
81. PC-Based Stepper Motor Controller 51
82. Digital Audio/Video Input Selector 52
83. Automatic Bathroom Light with Back-up Lamp 52
84. Simple Low-Power Inverter 52
85. Mains Interruption Counter with Indicator 53
86. Power-on Reminder with LED Lamp 54
87. QUALITY FM TRANSMITTER 54
88. MEDIUM-POWER FM TRANSMITTER 55
89. Four-stage FM Transmitter 55
90. Simple Short-wave Transmitter 55
91. Farmhouse Lantern-Cum-Flasher 56
92. Accurate Foot-Switch 57
93. Multipurpose Listening Device 57
94. Easy Transistor Tester 58
95. TV Pattern Generator 58
96. Sound-Operated Switch for Lamps 58
97. Remote Control using Wireless Doorbell 59
98. RF Signal Detector 59
99. Infrared Interruption Counter 60
100. Audio Mixer with Multiple Controls 60
101. Smart Loop Burglar Alarm 62
102. Temperature-Tolerance Checking System 62
103. Radiation Sensor 63
104. Stereo Headphone Amplifier 63
105. Whisker for Robots 64
106. Freezer Monitor Alarm 64
107. Photometer 65
108. Smart Emergency Light 66
109. Digital Camera Adaptor 66
110. Mock Alarm with Call Bell 67
111. Pocket-Size Reading Lamp 67
112. Rechargeable Torch Based on White LED 68
113. SMF Battery Guard 69
114. Multidoor Opening Alarm with Indicator 69
115. Brake Failure Indicator 70
116. Stress Meter 70
117. Clock Tick-Tock Sound Generator & LED Pendulum 71
118. Battery Charger with Automatic Switch-off 71
119. Earth Leakage Tester 71
120. Controllable Electronic Load Circuit for DC Power Supply 72
121. 16-Way Clap-Operated Switch 72
122. Bedroom Light 73
123. Inexpensive car Protection Unit 74
124. White LED-Based Emergency Lamp and Turning Indicator 74
125. Mains-Operated Christmas Star 75
126. LED Lighting For Christmas 75
127. Timer for Geyser 76
128. Multicell Charger 76
129. Light Dimmer that Doubles as 77
130. 220V Live Wire Scanner 77
131. Smart Switch 78
132. Power Failure and Resumption Alarm 78
133. Doorbell-Cum-Visitor Indicator 78
134. Zener Value Evaluator 79
135. Liquid-Level Alarm 80
136. Electronic Fuse 80
137. Bicycle Guard 81
138. Water-Tank Overflow Indicator 82
139. Simple Smoke Detector 82
140. Remote Emergency Alarm for Unmanned Lifts 83
141. Audio-Controlled Running Light 84
142. Power Supply Reversal Correcter-Cum-Preventer 84
143. Panic Plate 85
144. FM Adaptor for Car Stereo 85
145. Twinkle Twinkle X'mas Star 86
146. Simple Transistor Type and Lead Identifier 86
147. Mains Supply Failure Backup Light 87
148. Capacitor Evaluator 87
149. Signal Diode-Based Fire alarm 88
150. Blown-Fuse Indicator for AC load 88
151. Ding Dong Touch Bell 89
152. Low-cost Stopwatch 89
153. Digitally Adjustable Dancing Lights 90
154. Car Fan Speed Controller 90
155. Shock-Hazard Warning 91
156. IR Receiver Module Tester 91
157. In-Car Food and Beverage Warmer 92
158. Three-Component Flasher 92
159. 555 Timer PWM Audio Amplifier 93
160. Musical Water Shower 93
161. Night Lamp 94
162. Power Pulser 95
163. Continuity Tester With A Chirping Sound 95
164. Hot-Water-Ready Alarm 96
165. Electronic Combination Lock 97
166. Long-Range IR Transmitter 97
167. Automatic Parking Light For Cars 98
168. Peak Hour Timer 98
169. Panic Alarm 99
170. Heat Control Unit 101
171. Electronic Heart 101
172. Ultrasonic Sound Beam Burglar Alarm 102
173. Sunset Lamp 102
174. Electronic Dice 103
175. Solidstate Relay 103
176. Car Porch Guard 104
177. Wire-Break Alarm With Delay 104
178. Cordless Multidoor Alarm 104
179. Pressure-Sensitive Alarm 106
180. Crystal-Based 50Hz Generator 106
181. VISUAL AC MAINS VOLTAGE INDICATOR 107
182. Ignition for Old Cars 108
183. Versatile CMOS/TTL Logic and Clock Probe 109
184. School/College Quiz Buzzer 110
185. Multipurpose Listening Device 110
186. Anti-Sleep Alarm 110
187. DC Changeover System with Battery Protection Unit 111
188. Ultrasonic Proximity Detector 112
189. Another Ultrasonic Proximity Detector circuit 113
190. Turn Your Old Inverter Into An Emergency Power System 113
191. Speed Controller for DC Motor 114
192. Line-Powered Two-Tone Ringer 114
193. Audible IR Proximity Detector 115
194. Semiconductor Relay for Automotive Applications 116
195. Touch Alarm 117
196. Bedwetting Alarm 117
197. AC-Powered Led Lamps Without rectifiers 118
198. Easy Transistor Tester 118
199. Door Guard 119
200. Low-cost Night Lamp 119
201. Briefcase Alarm 120
202. Touch-Plate Doorbell 121
203. Sensitive LPG Leakage Alarm 121
204. Cupboard light 122
205. Simple Antenna Preamplifier for AM Radios 122
206. Multifunction Power Supply 123
207. Micro-Power Flasher 123
208. A Fourth-Order Speech Filter 124
209. Electronic Ludo 125
210. Smart Battery Protector Using a Shunt Regulator 125
211. Microcontroller-Based Tachometer 126
212. Temperature Indicator-CUM-Controller 126
213. Stabilised Power Supply for Prototyping 127
214. Infrared Burglar Alarm 128
215. Motorbike Alarm 129
216. PC Table Lamp 130
217. Audible Continuity Tester 131
218. Anti-Theft Alarm 132
219. Diac-Controlled Flasher 133
220. Stereo audio Distribution Buffer for headphones 133
221. Dual Motor Control for Robots 133
222. Optical Remote on/off Switch 134
223. Infrared Toggle Switch 134
224. Contactless Telephone Ringer 135
225. Automatic Wash Basin Mirror Lamp Controller 135
226. Auto Muting During Telephonic Conversation 136
227. Solar-Powered Pedestal Lighting System 136
228. LED Illumination for Refrigerators 137
229. Electronic Reminder 137
230. Photodiode-Based Fire Detector 138
231. Bodmas Rule 139
232. Circuit for UPS to Hibernate PC 140
233. Accurate 1Hz Generator 140
234. Environment Monitoring System Using Arduino 141
235. 3V PC Adaptor 142
236. Low-Cost Battery Charger 142
237. Street Light Controller 143
238. Light-Operated Doorbell 143
239. Simple Automatic Water-Level Controller 144
240. Simple HF Power Amplifier 144
241. Electronic Horn 145
242. Locker Guard 145
243. Demo Circuit for Over-Voltage Protection 146
244. Capacitance-Multiplier Power Supply 147
245. Wireless PA for Classrooms 147
246. Electronic Door Key 148
247. Optical Smoke Detector 148
248. Clock Tick-Tock Sound Generator & LED Pendulum 149
249. Earth Leakage Tester 149
250. Signal Diode-Based Fire alarm 149
251. Night Lamps 150
252. Continuity Tester With A Chirping Sound 151
253. Automatic Darkness-Controlled Lighting System 151
254. Contactless Telephone Ringer 152
255. Circuit for UPS to Hybernate PC 152
256. Variable Bench Power Supply With LCD and Monitor Display 153
257. Water Pump Controller 153
258. Propeller Message Display with Temperature Indicator 154
259. Stablised Power Supply for Prototyping 154
260. Propeller Message Display with TemperatureIndicator 155
261. Low-Power Voltage Doubler 155
262. Wind sound Generator 155
263. White / LF Noise Generator 156
264. Universal Battery Tester 157
265. Traffic Light Controller 158
266. Simple Pulse Generator 159
267. Simple low/high voltage cut circuit 160
268. Simple Frequency Meter 161
269. Musical AF/IF checker 162
270. Mini amplifier 163