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# I need a direction please.i need helpwith a circuit or idea please

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#### sweetguy4sure

##### Newbie level 3
Hi , i found your forum and i need some direction, im stuck on a project and have no idea how to solve the problem i have . First off im a mechanic and i have some electrical and mechanic backround. im also familiar with computers. im weak in electronic circuits. Im working on a project for cars that will help save alot of fuel with hydrogen fuel cell.I net good gains of fuel savings now but i want to go to the next step in the project. here is what i need . i need a type of controller that is able to control up to a 30 amp 12-14vdc out on a variable 1-3 volt input. In other words i can tap off the throttle postion sensor in the car that is 1 volt at idle (throttle closed) and 3 volts (throttle wide open). i need this to control a 30 amp unit through a pot or relays. 30 amps being wide open and 5 amps being idle.i need the amperage to correspond to the 1-3 volts the throttle position sensor .im using a 30 amp pulse width modulator that has a varible pot on it. i need to be able to control this pot with the throttle response. that would allow the system to gain even more mpg.allowing the fuel cell to be variable will allow the fuel curve to match alot better then just one set point as its designed today. any ideas? anyone? thank you for your time

If I read that correctly, what you are really asking for is a way of effectively linking a pot on the throttle (giving an indication of speed demanded) with another pot on the PWM controller (controlling the source of power).
This may be as simple as matching the voltages from the pots or it may need some math tweaking between them. What voltage is on the pot in the PWM controller at the moment and how is it connected?
If it does require an adjustement between the two pot voltages, you can either do it with an analog circuit or a digital one. Analog is possibly simpler but less flexible. Doing it digitally means using an ADC to measure the throttle voltage, doing something with the digital reading then converting it back to another analog voltage with a DAC. There are many variations on this theme, for example you might be able to generate the PWM directly from the digital circuit and simplify the power supply.

Brian.

Thank you for your response. i have been asking people here local for weeks how this could be done and everyone i know has been scratching their head. I was under the impression this wouldnt be a huge task but then again im not real good with cicuit design.. the pot is 12volts the pwm is this one shown below. i just need to be able to adjust the (fuel cell) in response to the throttle position to beter match the fuel curve and demand, the system can be tweaked and dialed in with this method bringing higher gains of fuel savings. any help with this would be greatly appreciated.. i did have the pot on the pwm mounted remotely and attached to the throttle unit itself which was effective but also would not be the same mounting for all viehicles. it would be standard to tap off the single return wire off of the tps. your help is greatly appreciated.

This is definitely doable, it will just require removing the pot on the controller and using the throttle voltage to generate the control voltage for the controller instead. You'll have to adjust is so that the 1-3V signal will give a full range of duty cycle on the controller (should be simple may require an extra op amp somewhere). No digital stuff required.

ok its obvious that you fellas are well versed in your knowledge as i am in my own field and thats great to see because i was losing hope. you guys have ideas and thats awesome to see. how hard would it be to hire someone to design a circuit for me to build and test ? im intelligent enough to solder and read most schematics, but not versed enough to actually know exactly what the components do. Thats just me being honest.intelligence i have but knowledge i lack in this area.so im not asking for free how too knowledge and would be willing to pay for a simple circuit design if need be. This knowledge would be something that would help shape the hydrogen conversion industry.

The kit is a fairly standard oscillator (IC1/1) and comparator (IC1/2) circuit to genearate PWM to drive the MOSFETs (MF1 & MF2). As 'mtweig' states, it isn't a particularly difficult task to do but based on experience with other systems, you will probably find you want to fine tune something or other or adapt it to work in different situations. That's why I suggested the digital approach, it makes it easier to cater for different situations and if necessary, monitor other system parameters to optimize the output. An analog system is fine if the input and output signals are proportional to each other.

You don't say where you are but I'm guessing the US based on the web link, I would be interested in helping with your project but I suspect I'm a long way away!

Brian,

We are in the US. Florida to be exact. We would love to have some help with this project. you will see you will be able to sell this circuit on ebay and will be readily accepted as people have talked about such a creature in the past but no one has come forth with a product to solve this issue. This will be a major step in the hydrogen fuel usage. we are getting ready to open a web site "Florida Hydrogen Systems" with in 2weeks it will be released. educating and selling systems and parts we already have been making. the addition of this new circuit will be all yours. we will gladly list all the rights and circuits sold for you. you could even have your own pay pal on our page so you get paid direct sales for your work . we are not greedy. we strive for efficency. this is what you will bring to our systems. so yes we would love to have a partner to help and share our knowledge and good working with. not to mention we will set you up with an hydrosystem of your own and start saving you money also along with lowering emissions and gaining power. you may email me any needs or wants and im sure we can work something out with someone to get this from thoughts to reality.. thanks

I'm still interested in helping but unfortunately, as well as being on the other side of the Atlantic Ocean, I have many other demands on my time.

To give you some guidance: you need to establish the exact parameters of your system first. A first step would be to take a working prototype and measure the optimum voltages at the two potentiometers under different conditions. If you plot a graph of one against the other you should see the function that the electronics has to replicate. This will give you an idea of the circuit complexity, for example, if you get a straight line all you need is a direct connection or at most a level shifter. If the line has a really odd shape it may need look-up tables and interpolation to make the conversion.

I'm still thinking you might be able to dispense with the PWM controller board altogether. Many microprocessors have in-built PWM generators and analog to digital converters. I means it may be possible to directly read the throttle voltage and generate the PWM power control in a single simple unit.

Brian.

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