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555 Variable Duty Cycle

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10 Threads found on edaboard.com: 555 Variable Duty Cycle
Actually, I want to use only one POT to change the frequency such that the duty cycle should remain fixed. Can't be easily achieved with a 555. A standard OP generator can do it, see post #2. Asymmetrical thresholds set the intended duty cycle, a single potentiometer the time comstant.
I don't agree about "unusual". A 555 circuit with feedback from output instead of DISCHG pin can be already found as 50 % duty cycle oscillator in the LMC555 datasheet. The variant with diodes and variable duty cycle is at least frequently used.
Hi i would like to make an frequency generator using a 555 timer chip. The frequency should vary in the range of 100hz to 1kHz with a reasonable duty cycle (20-80%). I am using the circuit below. Varying r2 alone would not do the job because at r2=0 the duty cycle is 100%. I found out if i started (...)
What will happen ???!!!!! what do you mean by that ? what do you want to do exactly ? you have a 555 TIMER , if you set it as A stable , it will work and oscillate as well . if you change D.C no thing special will happen . i don't know what is your exact aim .
Dear vead Hi It is a very sweet and easy project ! at first try to generate a variable duty cycle square wave . e.g with 555 . if you can do it , tell me , i'll illustrate you another step . Best Wishes Goldsmith
You can use a 555 timer in astable mode. You can find a schematic and calculator here . variable period and duty cycle can be achieved by using variable resistors and capacitors. You may also need to use the CONTROL pin.
hi in simple way u can use 2*(555) timer first one as stable the output of first one trigger second 555 connected as monostable and last one drive output stage with that connection u can adjust period and pulse width for drive signal
Hi I need to generate PWM signal for battery powered application to make ON/OFF for a swicth.The frequency is typically 1 second and I need to have a variable duty cycle by means of POT. I did look into 555 and 556 timer circuts and op amp PWM geneartion cicuits . It looks they all consume much current. Since it is (...)
hi, everybody.. I want to build a function generator by using 555 timer for signal generator and it capable of outputting a square wave with adjustable frequency in the ranges of 1Hz to 100Hz.. If anyone have an idea please let me know...thanks for your cooperation..:D
Hi masterx81, if your power source is DC, what you say (variable duty cycle with 555) is OK (for AC you could use a phase control wuth triac). A power MOSFET (as IRF520 or 6N10 among others) will be better than a bipolar transistor. It has very low ON resistance and very fast switch, so no power consumption. The gate can (...)