it would be better if you can provide some guidelines please?Welcome to AAC!
These modes of operation are described in detail in the datasheet. Do you want to try to do it yourself?
but , i tried this,From National Semiconductor:
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thanks, i will,Here's the circuit I suggest. I'll let you figure out the component values.
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Post a schematic for your circuit.but , i tried this,
when i give one shot, they stays on rather than flashing , then turned off. No flashing within the time period.
No. You need a one shot and an astable. If you use a 556, you can do it with one IC, but still 2 timers.is there no other way to do this with one timer?
Why? The 555s will do the job...Thanks a lot to everyone for the help.
But is there anyother way i can do it with LM339 using time constant ?
You can but it uses more components then a 555 circuit.But is there anyother way i can do it with LM339 using time constant
Thanks a lotBelow is the LTspice simulation of a circuit that should do what you want using one CD4093 quad Schmitt-trigger NAND-gate package, and a transistor to drive the LED.
Closing PB1 to ground (red trace) starts the pulses.
U1a generates the Gate signal ON time period (blue trace).
U1b is configured as a relaxation oscillator (green trace).
U1c is used as an inverter.
I(D1) is the LED current (yellow trace)
R3 & D2 set the initial voltage at RC to about 1/2Vdd, otherwise the first pulse would be about 2.5 times longer than the rest.
R4C1 determine the ON time, and R2C2 determine the pulse frequency.
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thanks a lotYes, but that's not what you asked for. You can use a LM393 which is the dual version of LM339.
Nat Semi Linear Applications Handbook 1994, AN-74:
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can you share the circuit with me ?You can make a short timer with a capacitor and single transistor, you could then use this to power a flashing type LED. I made a 13 second timer like this last year.