@crutschow i needed a suggestion for microcontroller could you help me in suggesting?

 

@crutschow i needed a suggestion for microcontroller could you help me in suggesting?

Sorry, I'm not that familiar with microcontrollers.
One of the resident micro experts will need to help you with that.

 

Here's a circuit using two small MOSFETs that shows very little change in delay (≈1%) for an ECU voltage between 12V to 24V.
The delay time can be varied by changing R1 and/or C1.

View attachment 157046

How would a circuit like that discharge the capacitor? A mosfet has a very high gate impedance. The next time it is powered up, how would there be a delay? So it might make sense to add a discharge resistor. Also, to avoid it being partially on, maybe use a BJT with a base zener, or a comparator.

 

How would a circuit like that discharge the capacitor?

It discharges back through R1 and R3 when the input goes to zero.

 

Consider a PSOC. All this analog stuff can pretty much be handled by a
combo of analog and digital on the psoc.

Attached is a components list. A component is a resource onchip PSOC.


Low end board is $ 4 or $ 10 PSOC 4

ttp://www.cypress.com/documentation/development-kitsboards/psoc-4-cy8ckit-049-4xxx-prototyping-kits

http://www.cypress.com/documentatio...s/cy8ckit-043-psoc-4-m-series-prototyping-kit


High end board is $ 10 PSOC 5LP

http://www.cypress.com/documentatio...oc-5lp-prototyping-kit-onboard-programmer-and


Tool and compiler free, PSOC Creator

http://www.cypress.com/products/psoc-creator-integrated-design-environment-ide


Some of the stuff on the chip -



Regards, Dana.

 

It discharges back through R1 and R3 when the input goes to zero.

I'm still a little confused. How does it do that?

 

I'm still a little confused. How does it do that?

I don't understand your confusion.
When the input goes to zero volts the cap simply discharges back through R1 and R3 to zero.

See the C1 voltage in the simulation below.

 

Oh, never mind. I thought the voltage was completely disconnected (like removing a battery), as opposed to it being connected to ground.

 

Oh, never mind. I thought the voltage was completely disconnected (like removing a battery), as opposed to it being connected to ground.

Yes, if it went to an open circuit then you would need to add a resistor (say 10kΩ) to ground at the input.

 

Here's a circuit using two small MOSFETs that shows very little change in delay (≈1%) for an ECU voltage between 12V to 24V.
The delay time can be varied by changing R1 and/or C1.

View attachment 157046

So in this last Vout will be either 12V or @24V???

 

So in this last Vout will be either 12V or @24V?

Vout will essentially equal Vin.

 

Sorry, I'm not that familiar with microcontrollers.
One of the resident micro experts will need to help you with that.

Crutschow i have query of adding delay in functionality of a comparator used for presence of water in fuel(for eg diesel),
here two pins will be used for sensing their respective presence at different heights, based on that we the respective voltage has to be compared and respective output has be sensed.
But here a delay has to given in output. How could i introduce an delay in a comparator circuit in simple and effective manner.
any suggestions.
for your reference i would add an model reference Comparator circuit below

 

How about using the circuit in post #15?

 

That function, delay, hysteresis, entierly within scope of UP. Thats
just A/D and maybe 10 lines of code. To setup and create test
result.

If thats the only functionality you need I would do it with ATTINY85
and bascom Basic Language.

See attached.

Regards, Dana.

 

Another alternate delay circuit using only one IC, five resistors, and two capacitors, that has only about a 0.1% variation in delay time for the input voltage change.

R5 and C2 determine the delay time.

U1 provides a fast discharge of C2 when ECU goes to zero.

View attachment 157148

We can use a single quad comparator and use it as two comparators na??
can you explain the process overflow
where the signals needs to be compared will be acquired where the delay will be done?

 

That function, delay, hysteresis, entierly within scope of UP. Thats
just A/D and maybe 10 lines of code. To setup and create test
result.

If thats the only functionality you need I would do it with ATTINY85
and bascom Basic Language.

See attached.

Regards, Dana.

Thanks for the suggestion.actually already worked with microcontroller...
now trying to do without microcontroller only with comparator as a cost reductive product.

 

Another alternate delay circuit using only one IC, five resistors, and two capacitors, that has only about a 0.1% variation in delay time for the input voltage change.

R5 and C2 determine the delay time.

U1 provides a fast discharge of C2 when ECU goes to zero.

View attachment 157148

As per my idea from the circuit,
R9 and R10 voltage dividers for reference voltage?
and R7 here is hysteresis purpose?
purpose of R6 is pull up resistance at output?

 

can you explain the process overflow

Is the delay circuit still powered solely by the input voltage or is there a separate power supply available?
Do you want a delay on both the high and low transition?

 

Is the delay circuit still powered solely by the input voltage or is there a separate power supply available?
Do you want a delay on both the high and low transition?

Yes i need for both high & low
high will be for some fuel and low will be for water
Supply from ECU(maybe 12-24V) input voltages which is to compared are from pins which will be seperate.
irrespective of sensing of high or low there should be a delay

To be precise, the delay has to be in the output(irrespective of whether high or low because here high or low is some presence of either water or fuel).
I'm i clear crutschow now?

 

Supply from ECU(maybe 12-24V)

So do you want the output to go between 0V and 12-24V also?