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.
Hobby Circuits and Small Projects Problems :: 01-18-2014 05:43 :: FvM :: Replies: 8 :: Views: 471
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.
Hobby Circuits and Small Projects Problems :: 12-29-2012 18:20 :: FvM :: Replies: 24 :: Views: 2410
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 (...)
Elementary Electronic Questions :: 08-08-2012 16:12 :: Faddei :: Replies: 13 :: Views: 5686
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 .
Hobby Circuits and Small Projects Problems :: 07-03-2012 09:31 :: goldsmith :: Replies: 8 :: Views: 1328
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 .
PLD, SPLD, GAL, CPLD, FPGA Design :: 03-27-2012 06:16 :: goldsmith :: Replies: 5 :: Views: 1135
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.
Hobby Circuits and Small Projects Problems :: 04-11-2010 15:34 :: Tagli :: Replies: 3 :: Views: 1513
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
Elementary Electronic Questions :: 12-14-2009 15:36 :: nashwan :: Replies: 3 :: Views: 1337
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 (...)
Analog Circuit Design :: 08-13-2009 00:55 :: manju_bhat :: Replies: 1 :: Views: 778
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.
Hobby Circuits and Small Projects Problems :: 09-15-2008 17:17 :: rkodaira :: Replies: 3 :: Views: 11214
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 (...)
Professional Hardware and Electronics Design :: 04-09-2002 19:18 :: zorro :: Replies: 5 :: Views: 1308