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555 Variable Duty Cycle

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10 Threads found on 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 (...)
You will not get a symmetric square wave with only the 555 (50% duty cycle) and a variable output frequency will change the duty cycle also. Try another IC like XR2206.
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 (...)