I have a sensor that gives a signal that varies from 0-4.5V the sensor is powered by 12 volts. The question I have is how do I get the signal to latch and hold at 4.5V once it has reached 4.5V, until there is a power off?

Any help would be appreciated.

 

1. Low power SCR, [ 2N5060 ], needs inverting to have a high output.
2. Flip-flop
3 Latching relay with driver
4. Dual input optical coupler
5. ?

 

Some sort of analog, comparator-triggered, sample-and-hold

Maybe a PIC with an ADC input and a DAC (PWM/low pass filter) output.


Ken

 

Maybe a latching comparator IC.

 

Sorry for the long time between replies, I was out of town over the weekend. I have looked at all of the ideas and one thing I noticed was that there was no cheap way to do it. Is there a cheap way to do this?

Thanks

 

Can you elaborate? Is this an automotive project? Does the sensor voltage drop below 4.5v after it reaches that value?

Ken

 

Yes this is an automotive project. The signal I need to latch goes from 0-4.5V depending on the pressure is applied to the gas pedal.

 

Sorry, the forum policy does not allow projects that could affect vehicle safety & connecting in to the throttle control is a very hazardous thing to do.

 

It actually doesnt attach to the throttle. I used a IR LED and Poximity sensor to measure the distance from the pedal to the floor.

 

Kinda changed directions alittle bit, Just wondering if this looks like a viable option for peak and hold.

Would this make the signal stay at the highest level that it reached until the switch was closed?

 

Yes...for a while. The capacitor will slowly discharge.

Ken

 

What would be a good op amp to use for this i tried a lm358 but it is not working at all for me?