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Found 4 results

  1. Circuit Diagram is given below: The circuit diagram of a three channel LED driver circuit using MAX7219 is shown below (Fig 1). C4 is an input filter capacitor. R1 is the resistor used for programming the output current. C3 is the output filter capacitor. C1 and C2 are the storage capacitors of the internal charge pump circuit. A logic high at pin 5 will enable the IC and a logic low on the same pin will drive the IC into shutdown mode. In the shutdown mode, the quiescent current is almost equal to zero. With the used value of R1, the LED current per channel will be 25mA. When powered up the MAX7219 operates in 1X mode i.e, the output voltage will be equal to the input voltage. If this output voltage is enough to regulate the current through all LEDs, the IC remains 1X mode. If the output voltage is not sufficient enough to regulate the desired current through the LEDs, the device automatically switches to the 1.5X mode where the output voltage is 1.5 times the input voltage. This process is repeated when ever the IC is powered up or awaken from shutdown mode. Can this circuit work? Actually,the LED driver in this circuit is CAT3063,however,I can't found this mode. I would like to use MAX7219 instead of CAT3063. Please give me some help! Appreciating!
  2. I want to charge a LiPo battery via the ballance plugs. So it's a ballanced charge, and I don't run into any problems, day in and day out.The light can be very small, but I want it to be bright. So even using a couple LEDs would make a really nice and bright mailbox light.I want the light to last all night long. So that means I need to know the current draw of the LEDs to the capacity of the LiPo batteries.etc.I need help on this. I need help with the fact how to use an Op Amp to shut the light off when it's daylight out.. or a specific amount of light is sensed.Light Sensed : Start charging, and turn off the LED lights.Light Sensed : Set the Op Amp to detect 4.2vdc. When it does, shut down the charging, &LED's stay off until darkness is detected.That's my idea of a mailbox light, with very long battery life, and high current solar charging abilities.Can anyone help me with this kind of circuit? Here is where my LED come from http://www.kynix.com/Search/led.html
  3. Hello. I made this circuit below: http://www.diy-electronic-projects.com/p270-Everything-that-moves-ALARM The circuit does not appear to be working properly, and I would like to get it working. To be honest with you, I never heard of a human body detector using eddy currents. The first image shows the pulses on the gate of the mosfet. They appear to be low duty cycle(around 15-20%). The other images show the pulses received by the smaller coil(5"/100T/26ga enamel wire) placed in the center of the 24ga speaker wire/5 foot diameter (5T) TX loop. The circuit can be set, but you cannot get it to trigger unless you actually touch/move the RX coil.The RX signal on the scope is more or less sinusoidal. Operating voltage is around 13.5vdc. Hopefully you can assist me. There is a 1000uF electrolytic capacitor across the power rail. Pins 4/8 on the cmos 555 and pin #14 of the 4093 are connected together to the + rail. Thanks,Doug
  4. This simple, one-transistor amplifier provides a voltage gain over 1000 (60 dB) for driving a high impedance ceramic (crystal) earphone. The high gain is achieved by replacing the traditional collector resistor with an unusual constant-current diode that supplies 1/2 mA yet exhibits a very high resistance to the audio. This amplifier will give excellent battery life, drawing only 500 uA. Below is a typical application using it with the first crystal radio circuit. The amplifier provides good volume with a modest antenna. You may want a volume control as with the TL431 project! Or use the Crystal Radio RF Amplifier directly above for even more sensitivity with less than 2 mA current drain.
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