Rongge

The operation of the dimmer is based on phase control; during a full cycle of an AC waveform, a thyristor will only allow a part of the waveform to be delivered to the load. Take a look at the following waveforms:   The only difference is that the waveform on the left will bright the lamp higher than the waveform on the right. That is because, on the left waveform, the triac will be conductive earlier than the triac shown in the right waveform.  The time that the triac becomes conductive is symbolized with the Greek letter α (ALPHA) , called firing angle, so controlling this angle you can control the phase voltage, and is measured in angles from the zero point of the waveform. This zero point is the point that the voltage is 0 volts, and this happens 2 times every one full period of the wave form. When the α becomes smaller, then the dimmer becomes conductive sooner and the lamp is brighter. When the α becomes bigger, then the triac delays more to become conductive and thus th...

Telephone line Based Audio Muting and Light-On Circuit . Very often when enjoying music or watching TV at high audio level, we may not be able to hear a telephone ring and thus miss an important incoming phone call. To overcome this situation, the circuit presented here can be used. The circuit would automatically light a bulb on arrival of a telephone ring and simultaneously mute the music system/TV audio for the duration the telephone handset is off-hook. Lighting of the bulb would not only indicate an incoming call but also help in locating the telephone during darkness. . Telephone line Based Audio Muting and Light-On Circuit diagram :   Telephone line Based Audio Muting and Light-On Circuit Diagram  . On arrival of a ring, or when the handset is off-hook, the inbuilt transistor of IC1 (opto-coupler) conducts and capacitor C1 gets charged and, in turn, transistor T1 gets forward biased. As a result, transistor T1 conducts, causing energisation of relays RL1, RL2, and RL3...

This lamp circuit using ultra-bright white LEDs provides sufficient light for reading purposes while consuming approximately 3 watts of power. In the case of AC mains failure, the battery backup circuit instantly lights up the LEDs. When the power resumes, the battery supply is automatically disconnected and the lamp circuit again works off AC mains. The power supply circuit consists of 0-7.5V, 500mA step-down transformer X1, rectifier diodes D1 through D4 and filter capacitor C1. Regulator IC 7805 (IC1) provides regulated 5V to LEDs, so there is no variation in the intensity of the lamp light even if the mains power supply fluctuates. A total of ten white LEDs (LED1 through LED10) are connected in parrallel across the 5V power supply. Resistors R1 through R10 (each 56 ohms) are connected in series with the white LEDs to limit the current. To increase the intensity of the lamp light, you can add more LEDs in the same manner; a maximum of 15 LEDs can be used for the lamp. LED-Based Read...

Rechargeable torches don’t come without problems. You need to replace the bulbs and charge the batteries frequently. The average incandescent light-emitting diode (LED) based torch, for instance, consumes around 2 watts. Here’s a rechargeable white LED-based torch that consumes just 300 mW and has 60 per cent longer service life than an average incandescent torch.  Rechargeable Torch Based on White LED Circuit Diagram Fig. 1 shows the circuit of the rechargeable white LED-based torch. The reactive impedance of capacitors C1 through C3 (rated for 250V AC) limits the current to the charger circuit. The resistor across the capacitors provides a discharge path for the capacitors after the battery is charged. The red LED1 indicates that the circuit is active for charging. The torch uses three NiMH rechargeable button cells, each of 1.2V, 225 mAH. A normal recharge will take at least 12 hours. Each full recharge will give a continuous operational time of approximately 2.5 hours. Recharge...

These metal detector circuit diagram is based on the TDA0161 monolithic integrated circuit , designed for metallic body detection by detecting the variations in high frequency Eddy current losses. For detecting metals , TDA0161 require an external LC tuned circuit . Metal Detector Circuit diagram Output signal is determined by supply current changes. Independent of supply voltage, this current is high or low according to the presence or the absence of a close metallic object. This metal detector circuit use two LEDs , which offer an visual indication of presence or absence at a metals ,around the coil . To adjust the circuit you need to make sure there is no metal near the coil and then set the fine adjustment to a "Mid position". After that you need to adjust the course adjustment to turn on the LED and , adjust the fine adjustment to turn off the LED. This detector electronic circuit operates over a wide range input voltage of 4 -35 volts .  If you want you can use other va...

One tool that I’ve been missing at my lab at home is function generator. They tend to be a bit expensive, so I haven’t bought one. I thought this might be a good opportunity to try and make one myself. I found a pretty common DDS (direct digital synthesis) chip, called AD9833. Then just strap a USB-enabled AVR micro there and maybe some analog electronics. This board doesn’t do any of the special analog magic to allow for variable amplitude or offset for the signal. The output is fixed to 0-4v. I’m planning to make another completely analog board for adjusting amplitude and offset. [ ]

This is power amplifier circuit using IC AN7108 as based for amplifier. See this circuit diagram below: Datasheet IC AN7108 Vcc                = 1-6,6 V Pout               = 2X 30 mW RL                 = 32 Ohm Ft                   = 20-20 Khz Icco               = 14 mA Package         = DIP-16 Manufactered = MATSUSHITA

Monitoring of an inverter during operation has being the major challenge faced by local inverter Manufacture which has lead to low demand for locally built Inverters due to sudden break down or Battery being overcharged. most of the Inverter schematic claimed or used by Local Inverter Manufacture downloaded from the internet are for tutorial purpose not not for commercial there are tendencies for failure therefore it is time for us to start developing things of our own... proudly NIGERIA...... The featuring M.C.U is the Microchip PIC16F876A FEATURES OF THE ABOVE SCHEMATIC ARE STATED BELOW : INVERTER PROTECTION : LOW-BATTERY SHUTDOWN                                              : OVER LOAD SHUTDOWN INPUT                                              : O/P SHORT CCT SHUT-DOWN INPUT                                              : HIGH TEMPERATURE SHUT-DOWN INPUT                                              : LOW-BATTERY : BEEP START AT 11 V                                              :INVE...

Description You can save on your electricity bills by switching to alternative sources of power. The photovoltaic module or solar panel described here is capable of delivering a power of 5 watts. At full sunlight, the solar panel outputs 16.5V. It can deliver a current of 300-350 mA. Using it you can charge three types of batteries: lead acid, Ni-Cd and Li-ion. The lead-acid batteries are commonly used in emergency lamps and UPS. The working of the circuit is simple. The output of the solar panel is fed via diode 1N5402 (D1), which acts as a polarity guard and protects the solar panel. An ammeter is connected in series between diode D1 and fuse to measure the current flowing during charging of the batteries. As shown in Fig. 1, we have used an analogue multimeter in 500mA range. Diode D2 is used for protection against reverse polarity in case of wrong connection of the lead-acid battery. Charger circuit diagram: When you connect wrong polarity, the fuse will blow up. For charging a lea...