circuit board to control a solenoid valve??? I don't know where to start

I am trying to design a board that has a source voltage of 12VDC. It needs to be able to watch a Throttle position sensor from .5v to 5v as the voltage increases the pedal is going from idle to wide open throttle. I need the board to send a 5v reference to a relay that will control the solenoid when ever the TPS voltage drops (let of the pedal) for example: Im at WOT and I press my clutch to shift in turn i will be letting off the throttle that is when i need a 5v signal to the relay to close the solenoid. Can anyone assist me in this. I stopped at Radio shack to see what they had and it looked as if there were some things there i could use just have no idea what to buy. I would also like to be able to delay the signal (ability to adjust the senstivity) and duration ( how long the valve will be held closed).

I saw a volt regulator for a circuit board that takes a max of 35vdc and outputs 5v so im assuming that will work for my signal to the relay. Also I saw potentiometer which im assuming could be used for the delay and a timer that could be used for the duration.

Thanks for the help in advance, this will be the first board I've ever tried to make so bare with me.

Jake Norton said:

I am trying to design a board that has a source voltage of 12VDC. It needs to be able to watch a Throttle position sensor from .5v to 5v as the voltage increases the pedal is going from idle to wide open throttle. I need the board to send a 5v reference to a relay that will control the solenoid when ever the TPS voltage drops (let of the pedal) for example: Im at WOT and I press my clutch to shift in turn i will be letting off the throttle that is when i need a 5v signal to the relay to close the solenoid. Can anyone assist me in this. I stopped at Radio shack to see what they had and it looked as if there were some things there i could use just have no idea what to buy. I would also like to be able to delay the signal (ability to adjust the senstivity) and duration ( how long the valve will be held closed).

I saw a volt regulator for a circuit board that takes a max of 35vdc and outputs 5v so im assuming that will work for my signal to the relay. Also I saw potentiometer which im assuming could be used for the delay and a timer that could be used for the duration.

Thanks for the help in advance, this will be the first board I've ever tried to make so bare with me.

Click to expand...

From your explanation it looks that you need a voltage comparator the output of which will drive the solenoid valve to ON or OFF position.
The other part is the timer which would respond by a delay proportional to the 0.5 to 5.0 V control voltage.

For the first task you need the driver for the 12 V solenoid, with o/5 V input. You now must find the solenoid current specification which will determine the switching element. Such element is usually a MOSFET like IRF 520 which, with a suitable heat sink can handle e.g. 5...10 A DC current.

The comparator will generate the 0/5 V drive for the MOSFET gate, by comparing a potentiometer preset voltage with the input voltage.

The comparator (and if needed) the timer are best powered from a 5 V DC power supply, you can use the 7805 voltage regulator with +12 V DC primary.

To design the above circuits, more specifications are needed, like the mentioned solenoid current, control voltage source, required timing., etc.

I think this is probably a good project for a small 8 pin micro with an analogue port PIC12F683 as an example, there are many others. I know that it is a steep learning curve especially if you have to learn coding as well. This allows for great flexibility and is well worth the effort. You could even make up a general purpose board with various inputs and outputs to use in many projects. If you wish to learn a programming language, probably something that Pic Basic would be a good starting point if you decide to use Pics. Another option is to use a pre built system, Raspberry Pi, Arduino etc etc. These have the advantage of readily available plug in boards for various I/O purposes so you don't need to build anything much. I you go along that route I am sure you will find it both facinating and rewarding. Good luck with whatever you decide to do.

I think the way I would approach this is to use two transmission gates driver by a square wave oscillator. A transmission gate is an electronic switch, which can pass a voltage (within certain limits) or block it. A square wave goes to a voltage for a certain period then returns to zero for the same time, then repeats its self. One gate is driven in the opposite direction to the other. So calling one square wave A and the other B, and their gates GA and GB.
So when the voltage from the sensor is rising, GB always has a more positive voltage coming out of it the GA. Likewise when the voltage is falling its the other way around. The trouble is that the outputs do not occur at the same time, rather one after another, so both the voltages are stored on a capacitor. So now the voltages occur at the same time, so taking one to the negative input of an op amp and the other to the positive input. It can be arranged that the output of the opamp goes from earth to positive for a brief period. This fast pulse can be used to trigger a timer to extend the pulse and hence the operating time of the relay.
Running the multivibrator at1 KHZ would allow you to sample the rise/fall of the sensor output every 1mS or so. You must have a serious think about the voltage fall time of the sensor. i.e. if the voltage drops .5V in .5 seconds or it falls .1V in .1 mS. This will determine the size of the storage capacitors, so they can charge up enough during the .5 mS and yet hold their voltage over the next .5 mS, then be discharged by the next pair of voltage pulses from the gates.
Frank

What if you try to start by using an already existing one?
https://www.sanhuaeurope.com/uk/en/products/electronic-controls , ok, they are chinesse but cheaper