What Is a Shunt Resistor?

I am astonished at that. No reflection on you; you only know what's being taught in the school/class. It was probably regarded as being too old-fashioned in the bright new world of digital electronics, but the basics should never be neglected, imo.

Quite - seems rather like not teaching arithmetic because everyone has a calculator.

Now you mention that, due to an admin c*ck-up, we had to do level 4 and level 5 maths in the same academic year.

I never did understand 'differentiation and integration'.

David

In this society, neither do many others.

Differentiation is rate of change.

Differentiate position with respect to time and you have speed. Your car's speedometer does this.

Differentiate speed with respect to time and you have acceleration.

Integration is a form of adding up, or totalising.

Integrate position with respect to time and you have distance travelled. Your car's odometer does this.

Nope it just adds up by counting wheel revolutions.

Differentiation is the slope of the graph. It's easy for a straight line (delta Y / delta X) but gets more difficult for complex functions. A (local) maximum or minimum of a function is found when the slope is zero.

Integration is area under the line. At it's crudest plot the graph and count the squares. It is always a multiplication. Area under a horizontal line starting from origin, is X * Y. Area under a straight line though origin again starting from origin is 1/2 Y * X. This is the basis for simple numerical integration using Simpsons rule.

If the odometer integrated distance over time it would be mile-hours. A fairly nonsensical unit of measure.

Hence you use it to integrate speed over time.

Odometer just counts. It's not getting speed as the signal so it doesn't integrate. It gets distance, each revolution of the wheel is a fixed distance (ignoring tyre wear). Doesn't matter how quick or slow those counts of 1 wheel revolution come it's always gone the same distance and each one adds one to the count.

A speedo does differentiation of distance / time. Old Smiths chronometric speedo had a clockwork, it went tick once a second. The revolutions of the wheel (speedo) or crank (tacho) were counted for 1 second and then the needle positioned at the number it had counted. The count was zeroed and started over. For speedo the scale was scaled to suit speed. For a tacho if it had counted 100 revs in last one second it pointed at 6000 revs per minute. What you saw displayed was the average speed or rpm over the last second.

Unfortunately.

It took a genius (well a couple of them) to devise the Calculus, it doesn't take a genius to understand it. When people fail to understand it, it is 100% the responsiblity of the teacher who has failed.

A shunt resistor is a resistor put into a 6 volt ignition circuit. It gets shorted out when the starter is engaged so that the ignition gets a good nu mber of volts (allows for the voltage drop when the starter is engaged) and back into action when the starter is no longer being operated, thus preven ting the full battery voltage from hitting the 6 volt circuit.

shorted out when the starter is engaged so that the ignition gets a good number of volts (allows for the voltage drop when the starter is engaged) and back into action when the starter is no longer being operated, thus preventing the full battery voltage from hitting the 6 volt circuit.

No, it's not. What you're describing is a dropper resistor.

shorted out when the starter is engaged so that the ignition gets a good number of volts (allows for the voltage drop when the starter is engaged) and back into action when the starter is no longer being operated, thus preventing the full battery voltage from hitting the 6 volt circuit.

More commonly called a ballast resistor when used in ignition system. Placed in series with the load. Limits current flow so the supply voltage drop is split between the ballast and the load.

A shunt is put in parallel.

It gets shorted out when the starter is engaged so that the ignition gets a good number of volts (allows for the voltage drop when the starter is engaged) and back into action when the starter is no longer being operated, thus preventing the full battery voltage from hitting the 6 volt circuit.

It all sounds a bit fishy. A shunt resistor can be used in connection with an Amp meter to measure higher currents, basically divirting most of the current through the shunt leaving a smaller current through the meter. Then getting the real current by an appropriate factor of the meter current.

A shunt resistor just means one in parallel with a load

gets shorted out when the starter is engaged so that the ignition gets a go od number of volts (allows for the voltage drop when the starter is engaged ) and back into action when the starter is no longer being operated, thus p reventing the full battery voltage from hitting the 6 volt circuit.

You're absolutely right! It's a ballast not shunt resistor. Apologies.