20 Threads found on edaboard.com: 555 Variable Duty Cycle
I would like to draw your attention to the CMOS version of the 555 circuit, the LMC555 from National Semi. or TLC555 from Texas Inst. and the astable mode working frequency is claimed to be 2MHz typically at Vcc of 5V. Its data sheet includes a diagram for 50% duty cycle operation too. See this link (...)
Electronic Elementary Questions :: 30.12.2006 00:22 :: unkarc :: Replies: 6 :: Views: 10387
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 :: 15.09.2008 17:17 :: rkodaira :: Replies: 3 :: Views: 10841
I don't really see the problem: at 150Hz the period is about 6.67ms. So if your filter has some 65ms time constant, you should be OK. With ony a 62k resistor you need about 1uF of capacitance. That can be even a surface-mount 0603 for voltages of 6V or maybe even 10V.
I am sure you can use a 555 to discriminate between the two (...)
Analog Circuit Design :: 26.01.2009 08:07 :: VVV :: Replies: 9 :: Views: 1782
Hello to all !!!!!!!!
I have designed the astable multivibrator using 555 which has been modified for variable frequency and variable duty cycle ranging from 30 to 80% using two diode but problem is with me is i am not getting the desired output of pulses when i am trying to get for 5 kHz freq. but the (...)
Hobby Circuits and Small Projects Problems :: 07.05.2009 07:00 :: pleasure :: Replies: 5 :: Views: 3563
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 :: 03.07.2012 09:31 :: goldsmith :: Replies: 8 :: Views: 1163
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 :: 29.12.2012 18:20 :: FvM :: Replies: 24 :: Views: 1808
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 :: 09.04.2002 19:18 :: zorro :: Replies: 5 :: Views: 1172
Output of comparator is square wave with variable duty cycle and frequency depending on audio signal. Purpose of diode and RC behind it is to give average value of comparator output. RC filters out frequencies above 2Hz and thus the output voltage is lower. In this way only the frequencies below 2Hz can be used for control and they have full (...)
Electronic Elementary Questions :: 30.04.2006 02:21 :: Borber :: Replies: 5 :: Views: 1057
The 555 timer frequency depends on the supply voltage as well as timing resistors and capacitor. The problem might be due to supply voltage drop when the motor draws current from it.
I suggest you use the popular TL494 PWM IC. It simple to use, gives much improved performance than the 555, and still cheap.
If you insist on the 555 timer, (...)
Analog Circuit Design :: 07.04.2007 17:46 :: amrstaha :: Replies: 2 :: Views: 998
It's not understandable, how the two observations are related. A LM2917 f-V converter can't directly interface the sensor. Thus LM2917 problems are a different topic. You probably have a wrong circuit.
Generally, a variable resistance or capacitance sensor signal can be directly converted to a voltage variation by using two 555, one as an astabl
Robotics and Automatics Forum :: 10.12.2008 13:30 :: FvM :: Replies: 10 :: Views: 6624
I need a circuit in which the frequency of LM555 astable multivibrator can be controlled externally I mean by the help of transistor etc. So, please guide what modification may be done in the attached circuit
Hobby Circuits and Small Projects Problems :: 16.06.2009 01:25 :: xyz9915 :: Replies: 13 :: Views: 10894
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 :: 13.08.2009 00:55 :: manju_bhat :: Replies: 1 :: Views: 638
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
Electronic Elementary Questions :: 14.12.2009 15:36 :: nashwan :: Replies: 3 :: Views: 1176
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 :: 27.03.2012 06:16 :: goldsmith :: Replies: 5 :: Views: 982
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 (...)
Electronic Elementary Questions :: 08.08.2012 16:12 :: Faddei :: Replies: 13 :: Views: 3584
The circuit is a fully-developed versatile driver for the electrodes (arc welder, I guess). All the components are popular.
It is versatile because you can vary the frequency and duty cycle to the electrodes.
If you wish, you can experiment with just the 555 timer IC driving the mosfet. There are easy ways to adjust the frequency and (...)
Analog Circuit Design :: 19.04.2013 16:32 :: BradtheRad :: Replies: 5 :: Views: 534
I doubt if SG3524 can give 0% to 100% duty cycle adjustment. thjere will be some
You can also try the standard 555 Timer Ic.
PC Programming and Interfacing :: 15.07.2005 10:35 :: rauol :: Replies: 2 :: Views: 1962
Well I am not an expert but I think you can use 555 timer circuit in astable mode to generate the strobe for LED's. Microcontroller really required here?
I am attaching some theory and pspice simulation results which can help you understand the 555 timer operation in astable mode. Even if your are not using 555 go through this to help u (...)
Analog Circuit Design :: 21.03.2010 03:02 :: abbeyromy :: Replies: 5 :: Views: 3481
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 :: 11.04.2010 15:34 :: Tagli :: Replies: 3 :: Views: 1308
Hi, I am working on a similar project:
I have verified that using a isolated power supply for the gate drive circuit will turn the N channel mosfet on and off in a Buck circuit configuration with a 12 volt battery as a load. I configured the gate drive circuit with a 555 time and used a Schmitz
Power Electronics :: 01.04.2012 22:00 :: BurnIt0017 :: Replies: 1 :: Views: 1127