Low Voltage relay or switchable unit??

system is on a 12v car electrical system

I am using a 0-5v DC MAP sensor to control a servo that is 0.6-5v....
My question is what can i use if i wanted to introduce a controlled 4.5-4.9v into the circuit... at a particular voltage range...

if the MAP sensor output voltage is less then 2.28vDC... what can i use to block the 2.28v and less and switch to an (4.5-4.9) controlled voltage intput.. then when the 2.28v on the MAP sensor is reached or passed it would kick out the controlled voltage and use the MAP 2.29-5v to control the servo...

Basicly i want to make the servo stay open at 0-2.28v and then be controllable based on the input voltage off the MAP from 2.29-5v...

Thanks for the help.. and sorry for the confusing...

is there know one that knows how to help me out....im not very electrically knowledge.. i know the basics and how to solder.. but i don't know the technicality's..

storx said:

system is on a 12v car electrical system

I am using a 0-5v DC MAP sensor to control a servo that is 0.6-5v....
My question is what can i use if i wanted to introduce a controlled 4.5-4.9v into the circuit... at a particular voltage range...

if the MAP sensor output voltage is less then 2.28vDC... what can i use to block the 2.28v and less and switch to an (4.5-4.9) controlled voltage intput.. then when the 2.28v on the MAP sensor is reached or passed it would kick out the controlled voltage and use the MAP 2.29-5v to control the servo...

Basicly i want to make the servo stay open at 0-2.28v and then be controllable based on the input voltage off the MAP from 2.29-5v...

Thanks for the help.. and sorry for the confusing...

Click to expand...

hi,
The first I would do is to measure the MAP output signal to ensure its 'dc' and not 'PWM'...
A dc voltmeter will give a reading even if the MAP signal is PWM.
You should use an oscilloscope to confirm the MAP signal voltage.

If it is PWM, a basic comparator circuit will not work correctly to give the required switch over voltage.

Measure the signal using a scope and observe the MAP signal, post back what you see.

**broken link removed**

this is a pic of the voltage going from vacuum (0.6v) to full psi 14.8psi (4.6v)

Not installing an HHO system I hope.

No, im trying to use the MAP sensor output voltage on my turbo system to control the VGT slidevein on an aftermarket turbo im trying to install on my autoX car... i mounted a servo from an throttlebody that uses drive by wire to control and mounted it on the turbo with the servo connected to the linkage of the slidevein to move the slidevein as voltage changes on the servo... That is as far as i have gotten.. i can use a 0-5v powersupply to make the turbo slidevein move via the servo..... and i have a chart of the voltages of the MAP on the car.. were 0.6v is 25hg vacuum and 2.28v is 0.00-psi and 4.6v is 14.80psi.....

Now what i want to do is use the MAP to control the servo on the turbo now..but i wanna take it one step further... i dont need the slidevein to close under 0.00psi so i want to use a circuit to make it default to 4.6v when the input voltage from the MAP is under 2.28v..... so the slidevein would be open and when 2.28v from the MAP is seen it switchs from 4.6v to the MAP input and allows the slidevein to close and open up as the MAP voltage increases from 2.28v....

Use a PIC.

They can read in 0 - 5 V on the ADC, and you can output 0 - 5 V using either PWM output or an external DAC.

With a PIC you need a programmer and you need to learn to program it.

You can design it analogue, with op-amps and diodes etc and it will use just about the same number of components.

Then when you change your mind as to how it should work, with the analogue design, you start again, or bodge in extra components and it looks a mess.

With the PIC you write a few more lines of code and upload it.

Diver300 said:

Use a PIC.

They can read in 0 - 5 V on the ADC, and you can output 0 - 5 V using either PWM output or an external DAC.

With a PIC you need a programmer and you need to learn to program it.

You can design it analogue, with op-amps and diodes etc and it will use just about the same number of components.

Then when you change your mind as to how it should work, with the analogue design, you start again, or bodge in extra components and it looks a mess.

With the PIC you write a few more lines of code and upload it.

Click to expand...

i have no clue what your talking about.. could someone maybe simplify it a little or post a link to something i could go read to learn more of what your talking about.. i wanna figure this out.. but the more help i can get would be much appreciated..

Thanks in advance...

storx said:

i have no clue what your talking about.. could someone maybe simplify it a little or post a link to something i could go read to learn more of what your talking about.. i wanna figure this out.. but the more help i can get would be much appreciated..

Thanks in advance...

Click to expand...

hi,
As the signal appears to be a 'dc' voltage, it would be possible to use a comparator ic [LM393] to close/energise a relay when the MAP voltage reaches a certain level and open/de-energise the relay below the the set level.
The relay contacts would be used to control the external circuit.

Do you follow OK.?