Timer Definition and 126 Threads

I need to build a timer(using a 555) with a frequency of about 1KHz and a duty cycle of about 25% to provide my clock signal. So the 555 is obliviously in astable mode. From my engineering data sheet: D=\frac{R_B}{R_A+2R_B} f=\frac{1.44}{\left(R_A+2R_B\right)C} where C is my capacitance value...

Hello All, I'm working on a project that requires an isolated switching supply that will output 15V from a 9-18V input at up to 2W. I have found the perfect DC-DC converter module for the job from MicroPower Direct but I'm trying to see if it would be possible to build something with similar...

Is it possible to create a 556 timer from two 555 timers rather than just purchasing one 556? Thanks

Hi everyone, I have been measuring some times for an application I'm doing, using some source code I found on the internet for measuring system time and user time used by an application. I am getting some very strange results though, and I wanted to ask if they were possible or were maybe...

How would i do this?

Hi, everyone. I am currently involved in a small electronics project and I am required to produce a time delay for part of the project. I plan on using the famous 555 timer and not quite sure on what to do to produce this delay.So please anyone help explain how to produce a time delay of,say...

hey guys... I'm having some trouble trying to figure out how to trigger a siren I'm working on. i have an astable circuit setup with the output of the monostable 555 connected to the output of the astable 555s to trigger the circuit. i wanted to trigger the circuit using a PIC microprocessor but...

[SOLVED] help 555 timer problem hi all, i am designing a 555 on astable mode. it is designed to operate at 100kHz with a duty cycle of 95% ( and i get 48Khz and duty cycle 93.5%). i calculated all the values necessary: Ra = 12.987 kOhm Rb = 721.5 Ohm C = 1nF F = 1.44/ ((Ra + 2Rb)*C)...

I need help buiding a circuit that would use a potentiometer to control power from a small battery (AA's, 9 volt, or similar) to a small electric motor. I would like to have the motor pulse on for @5 seconds and then go off. The 5 seconds "on" would remain constant, but I would like the pot to...

Help! I need to make an adjustable timer circuit with 7-Segment Display Readout for a science project. Please help.. I don't also want to spend a lot of money on this, so please tell the parts and circuit diagram I need. Thanks in advance. -Circuit Man

I was using a 555 timer circuit to generate a tone the frequency of roughly 256 Hz with resistors of 22 and 270 Ohms and a capacitor of 10 uF but I was advised not to by my teacher and wasn't able to ask the reason why. Can someone kind of brief me on this since my teacher is away tomorrow and...

So I will start off saying that I am not a genius when it comes to this stuff quite yet, but i have done several EE classes(slow but its going) and tinker around for fun. But for some reason this 555 Timer(i have a 556 Dual Timer) is just not working and i can't tell if its a faulty chip or...

Hi all, great forum here. Hope to learn a lot. I am looking for a sample LM555 circuit. In simple terms I am looking what I think to be a reverse of the monostable circuits I have seen. More or less I have a switch that needs to be held down for 1 sec before the circuit is active (pin 3...

I hae built a MK111 variable interval timer http://www.maplin.co.uk/Module.aspx?ModuleNo=25224&criteria=TIMER%20KITS&doy=6m1" and intend to use it for a free-flight glider which is a university project! I wish for the timer to power an electric motor for 2sec and then pause for a desired...

Homework Statement Refer to the uploaded file, Which of the following statements is/are correct? (1) The length of each tape represents the average velocity within the time interval. (2) The width of the tape represents the constant time interval. (3) Joining the centres of the tops of...

What am I doing wrong (555 timer as a one-shot)?? I'm trying to use a 555 timer to produce a quick pulse whenever a switch is switched a certain way. I have it set up exactly as the data sheet describes (attached picture) and am using a 47 micro Farad Cap as C1 and a 1k ohm resistor. I have the...

Hello I currerntly have this circuit - https://www.physicsforums.com/attachment.php?attachmentid=8419&stc=1&d=1164497449 circuit1.jpg I am trying to keep it as simple as possible. I have scoured loads of site etc, an have even found the circuit I want, or should I say it is described as the...

First timer needs help! With theory of electric motors Hi, I was wondering if anyone could please explain (or redirect me to) the basic theory in how by spinning a motor in its opposite direction, it produces current. I am conducting an experiment on the amount of current that can be obtained...

Hi, I have a 555 timer IC. For my work, my colleague asked me to make it so it can output 100 KHz frequency. (astable) My Ra = 6.8 kOhms and my Rb = 4.7 kOhms... I know that the Frequency = 1 / (T_high + T_low) where T_high = 0.693(Rb + Ra) * C T_low = 0.693(Rb) * C Although I'm not...

Hi, My circuit is using NE555 timer to active a solenoid driver for some seconds. I have finally found out that any time we turn the power ON, the circuit is initially running. I have wondered that, when we turn the power ON, the power switch creates a signal as a voltage, so that can...

Hi everybody, I have set up a 555 monostable timer to run a solenoid for 0.05 seconds - very rapid on then off, moving the solenoid about 3 mm. I have found that it is not producing quite enough force for what I need and was wondering if I put 6 vdc solenoid in place of the 12vdc solenoid...

Hi , I'm new here =) . This is from my homework . My teacher let us do the ticker timer's experiment with 50 GHz . after that , we r suppose to calculate the total displacement and the average velocity and also the acceleration of the trolley . we cut the tape into 5-tick strips and pasted into...

Hi! I need to programme a 555 timer pulse with intervals of 4 secs. I've already tried connecting a monostable circuit I found on the net with values of a 36K resistor and 100uF capacitor but what's happening is it's going on for 4 seconds then off for the rest! Here's the circuit that I...

Is there such a thing as a morse code ic timer chip or is the only way cascading 555's or something complicated like that. Eproms and machine code is ok if that's what it takes if its cheap and easy for my pc. Only need maybe 3/4 pulses timed. EDIT: want to modify my intercom into a system...

Hey, I just signed up and I've already got a question. =) The answer was in the book but I don't get the answer. Determie the frequency of a spark timer set at a period of 0.10s. Ans: 1.0 x 10¹ Hz. The book only says; The answer is literally staring me right in the face and the...

Hi Can You Help Me I Need A Timers Cercuit @ 1 Hour @ 2 Hour @ 10 Hour Please Help Me