answersLogoWhite

0

The 555 timer can be configured in a variety of ways. When used in a tachometer circuit it is configured as a monostable vibrator, ie a device that has one stable state on its output terminal. Let's consider that state as "OFF" .

If a trigger pulse is sent to the input it will turn "ON" for a fixed period of time set by the circuit time constant then turn "OFF" again.

Consider a single cylinder four stroke petrol engine firing once every two revolutions and revolving at 1000 rpm. A strong pulse will be generated from its ignition circuit 500 times a minute - or every 120 milliseconds. With some

pulse shaping and amplitude limiting, a pulse can be derived from this to trigger the monostable vibrator from "OFF" to "ON"

Let's assume that the monostable time constant components are chosen to make the fixed width output pulse be 20 Milli seconds and a current measuring meter is connected to the output and adjusted to read one fifth of full scale deflection - ideally marked "1000" on its scale.

Now as the speed of the engine is increased, there will be more and more 20 Milli second pulses at the output and the meter reading will rise linearly in proportion to the engine speed because the meter movement will respond to the average current.

In this particular case, with a 20 millisecond output pulse, when 5000 rpm is reached the trigger pulses are now arriving every 24 Milli seconds and the 555 output will be "ON" for 83% of the time. The meter will have reached full scale deflection.

Above 5000 rpm this example would soon become unstable and inaccurate.

Pulses from other types of rotating machinery can be derived optically or magnetically to trigger a tachometer like this.

User Avatar

Wiki User

12y ago

What else can I help you with?

Related Questions

How do weigher work?

A small section of the conveyor belt is weighed using Load Cells and the belt speed is measured using a tachometer. The outputs from the Load Cells and Tachometer are fed into an electronic integrater box which calculates and displays the rate, which is usually in tons per hour.


Mazda b2500 tach works speedometer does not?

The Mazda tachometer and the speedometer have separate cables. The tachometer cable probably does not work properly. Change the tachometer cable.


How do belt weighers work?

A small section of the conveyor belt is weighed using Load Cells and the belt speed is measured using a tachometer. The outputs from the Load Cells and Tachometer are fed into an electronic integrater box which calculates and displays the rate, which is usually in tons per hour.


How does a digital stopwatch work ?

A digital stopwatch is a timer usually used to record the time it takes to cook something or for athletes who need to have their running time recorded. There is a start/stop button and also a lap button to mark a lap has been completed.


If you had a speedometer with a tachometer and you replaced it with a speedometer without a tachometer will it work?

it sure would work.. behind the dashboard are plugs for each function. one for tachometer, one for speedometer, fuel, water temp. ect.. if your new dash doesn't have a tachometer it will not interfere with the speedomet aspect of it. but you will not have a tach obviously. that sucks kid


Your tachometer on your 1996 ford explorer does not work why?

One possibility is that the tachometer connections to the circuit board of the cluster have become corroded. It is also possible that the tachometer has just become worn out and needs to be replaced.


How does a clockwork egg timer work?

A clockwork egg timer works by using a spring mechanism that slowly unwinds over a set amount of time. When the timer is set, the spring tightens, causing the timer to count down until the spring fully unwinds and a bell or chime alerts that the time is up.


Why will the tachometer odometer and speedometer not work on a 1995 Silverado?

because they are broken.


Why does your tachometer not work on my 2005 Kia Sedona?

rev counter not working


What would make a 92 sc400 miss fire and tachometer not work properly?

There are several things that can cause your engine to misfire and the tachometer to not work properly. The most common cause is a malfunctioning vacuum hose.


My tachometer only works about once per year. How do you check for loose connections on the tachometer in a 99 Honda Civic Si?

If the tachometer only works a few times a year the VSS is malfunctioning. This can occur when oil is spilled on the unit and messes with the sensor. Cleaning the sensor will allow the tachometer to work properly.


Is a computer an analog device?

The majority of modern computing devices are digital. That means they work by using many on and off type electrical signals. Analog computers work by using vary ranges of constantly-changing signals in real-time without converting them to digital sequences first.

Trending Questions
Find the probability of getting a total of 8 in a pair of dice is tossed? Based on the data in the data table what can you infer about the relative length of time an onion root tip cell spends in each stage of cell division? What is the definition of most? What does it mean 100 percent chance of precipitation? Which software program is used to analyze qualitative data? How do line graphs help investigate the relationship between two sets of data? How long does it take to get gonorrhea test results? Is 75 grams greater than 5 oz? The techniques used to find out something about a population such as their average age based on a sample are referred to as? Which is not an advantage of using a histogram to represent data? What is the probability of a down syndrome carrier male and a non-carrier female producing non-carrier children? The geometric mean for 3 and 15? What is the probability of a missile guidance system with 7 fail-safe components with the probability of each failing being 2 assume the variable is binomial? What is the probability of pulling out a red marble then a blue marble without replacing the red marble the bag contains 3 red marbles 2 blue marbles and 5 green marbles? How long does marijuana stay in your system if you have you have a high matabulism? How many unique ways are there to arrange the letters in the word HATTER? What are the application of application? What is the probability of getting a black pen if you have 4 black pens 6 blue pens and 2 red pens? What is the probability that the first card drawn is a spade given that the second card drawn is a spade? Suppose you roll two dice what is the probability of rolling a sum of 7?