The title doesnt explain it very well but I couldnt think of a better one
Its probably easier for me to say what the circuit is to be used for first to make it easier to
understand what I need to do
in a car engine the speed of the car is proportional to the speed the engine is turning at
so if for example you get 10 MPH at 1000 RPM you will get 20MPH at 2000RPM so logically
the sound of the engine note goes up in proportion to the speed of the car
I am fitting a sound unit into a large scale model train
the throttle is a pot that gives a variable output of 0v to 5v and this feeds a PWM circuit to control the motor. It also goes to the input of the sound board so as the train speed increases the engine note rises.
and all that sounds great but it isnt.
My train is a model of a diesel hydraulic and the speed shouldnt follow the engine sound in the same way .When you open the throttle ( even to full throttle ) the train should start reving as you would expect but pull away slowly and increase its speed till it reaches that set by the throttle but this should take a few seconds , and the same with slowing down, shut the throttle and the engine note drops right down but the train slows gradually again over a few seconds . Its a bit like driving a car with a badly slipping clutch
So , the pot I need to use as the throttle should still give me a voltage between 0-5v that follows the throttle lever for the sound board but also a second output that has a delayed rise and fall for the train speed ( I will try to upload a picture to show basically what the two signals are doing versus time.
I am assuming it could be done by taking the output of the pot to a capacitor and resistor that would limits its charging/discharging rate but I am not sure how to do it or what sort of value cap and resistor to use .
Any ideas would be appreciated