How do I make a 555 NOT respond so quick?

[oldiemotors]

Building a board to test Cruise Control modules. A 555 is used to simulate a vehicle speed sensor (VSS) pulse. Using 200K linear pot as my Rb resistor in the following circuit:

The CC module manipulates the pot as it attempts to maintain the set speed.

I am trying to figure out how to introduce some lag time between when the CC module moves the pot and when the pulse rates change. Right now, when the pot moves the change in the 555's pulse rate changes instantaneously. This immediate response is not ideal for this installation.

Thanks for any help...

 

[MikeMl]

Seems like you need a voltage-controlled 555. Put an RC delay circuit between where the pot makes the control voltage, and where the control voltage adjusts the frequency of the 555. The Pot position simulates the deflection of the accelerator pedal, the RC delay simulates the acceleration/de-acceleration of the vehicle, and the 555 simulates the vehicle speed.

 

[oldiemotors]

MikeML,

Did a little research on your suggestion, but I have not been able to find much on how to calculate the values for the additional RC circuit. I can experiment with different values this evening, but can you give me any ideas how to calculate values for the additional components?

Thanks,
Daryl

 

[oldiemotors]

Getting closer

I took Mike's advice and am using a pot to vary the voltage to the #5 pin on the 555. I am trying to get a frequency out of the 555's #3 pin that varies between around 75Hz - 220Hz. Can anyone tell me if I am on the right track, and/or tell me how to calculate the values for this 555 circuit to achieve those frequencies?


Thanks,
Daryl