Decreasing current in preload circuit

[rrburkha]

I am working on a preload circuit and am having a difficult time with it. The objective is to apply .15A @ 24V when a control signal reaches 7.5V and decrease current in a somewhat linear fashion to 0A when the control signal reaches 10V.

I was looking into a voltage controlled resistor circuit using a FET.

Any other suggestions or help would be appreciated.

 

[berkeman]

I am working on a preload circuit and am having a difficult time with it. The objective is to apply .15A @ 24V when a control signal reaches 7.5V and decrease current in a somewhat linear fashion to 0A when the control signal reaches 10V.

I was looking into a voltage controlled resistor circuit using a FET.

Any other suggestions or help would be appreciated.

Sounds like you could use a voltage-to-current converter circuit with an opamp and NPN transistor. You'd gate that circuit with the output of a comparator circuit that tests the input control signal voltage against 7.5V (with a little hysteresis built into the comparator, of course).

Can you sketch something like that up?