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Hello,
Need suggestion LED Blue and REd transparent flashing/flickering from 555 or BJT which is best??
and what cell should be there, the order is of 1lakh pcs.
The minimum supply voltage for a ordinary 555 is 4.5V. Then you need a battery that is 6V or more when new.
I buy a garden light at The Dollar Store. It has a color changing LED that some fade slowly between many colors and others flash red, green then blue fast then slow then fading.
The LED has 3 LED chips and a microprocessor inside. The garden light comes with three 1.5V button battery cells, a current-limiting resistor and an on-off switch. It costs only $1.00 and its parts are worth much more.
I buy a cheapo white solar light at Wal-Mart for $1.00 and use its solar panel, AA battery cell holder and circuit board that boosts the 0.8V to 1.4V from the battery cell to about 4 volts and turns on the LED when it gets dark and charges the battery when there is light. I replace the white LED with the color changing LED adding a Schottky diode and filter capacitor. Of course I replace the very poor quality Chinese rechargeable battery cell with a good one.
Hello,
Need suggestion LED Blue and REd transparent flashing/flickering from 555 or BJT which is best??
and what cell should be there, the order is of 1lakh pcs.
A Cmos Schmitt-trigger inverter IC has a fairly low output current when its supply voltage is low. It can drive a transistor that drives an LED.
There is ordinary CD4xxx Cmos that has a minimum 3V supply and there is 74HCxxx Cmos that has a 1.5V or 2V minimum supply.
An oscillator can be made with a Cmos Schmitt-trigger inverter with the inverter, a resistor and a capacitor like this:
The frequency of the Cmos Schmitt-trigger oscillator is determined by its capacitor and resistor values. Higher values produce lower frequencies because then it takes longer for the capacitor to charge and discharge to the Schmitt-trigger threshold voltages.
A second inverter inverts the signal so that the oscillator turns on an LED and the inverter turns off another LED then they alternate.
There are about thousand different varieties of Schmitt triggers in different logic families.
If you aren't familiar with any, then here's the basic DIP package in a 74AC14 that follows previous advice. This works for <=6V, others like the 'HC14 for a higher range but slightly different hysteresis.
Voltage - Supply 2 V ~ 6 V Current - Quiescent (Max) 2µA Current - Output High, Low 24mA, 24mA Logic Level - Low 0.5 V ~ 1.1 V Logic Level - High 2.2 V ~ 3.9 V
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