Schematics Variable current 12v 60A to 0A

[ante1]

Dazza, The dropout voltage for a standard regulator is 2Volts. A 78S09 (the S is a 2A regulator- the ICL7667 require this) regulator will work down to 11Volts but no less. This is fine for a 12Volts system, but when switching to a 24Volts system, which can be as high as 28.5V suddenly, the 78S09 will dissipate almost 40Watts (worst case). That

 

[Dazza]

Ante, I have a listing in my jaycar Catalogue, for a low ESR capacitor. It tells me that it has, impedance MAX 100KHz, stable low impedance characteristics, high ripple current, will this do the job. Is there a certain type of capacitor I should be using. Am I on the right track in understanding what's going on here. The (ICL 7667) and the MOSFETs have a capacitance, so this needs to be supplied voltage from a capacitor, that can discharge quickly enough, to supply adequate voltage to these components, and can keep up with the fast switching. The capacitance would have to be fairly large for this capacitor, if I was to add more MOSFETs. The resistor to the MOSFETs gates, should be of very low resistance?, will this resistor be dissipating a lot of heat?. I should use A 15V 3A regulator, and a 5V 1A regulator,and keeping in mind their maximum voltage that they can handle, and the dropout voltage of the 15V regulator. The large low ESR capacitor, will need to fully charge through the regulator at start-up will this bother the regulator. Would it help to add a diode between the regulated side of the regulator's to share the load at start-up, or would it not matter. Or is this another one of my silly suggestions, I didn't think through ;D. Can you see any mistakes on my schematics. Or should I say, how many mistakes can you find ;D ;D

. I still have two consider the pin out, for the regulator's.

View attachment 35861

 

[ante1]

Any low ESR cap will do the job. As I think you know a capacitor resists any change in voltage, so does any other component with a capacitance. This is what makes a voltage change require high current. The driver (ICL7667) will consume high current to switch the mosfets in and out rapidly. A low ESR capacitor is capable of supplying high current with short notice a little better than a standard cap. The regulator will get a beat when the supply is turned on at first but they can take a good punch so not to worry. No diode is needed, L1 will take a part of the beat at startup but remember the current rating for this one also. I don

 

[Dazza]

Ante, can I parallel chokes. Shouldn't I also be keeping them away from the IC's, because of the magnetic fields they create. What value resistor do you think I should try, to the gates of the MOSFETs, should I use 1watt resistors. When you get the time to look at the schematics ante, is plenty soon enough for me, don't be in a hurry. Your time and knowledge that you have already given me, is very much appreciated .

Thanks ante.

 

[Dazza]

Well my request for free sample from Texas Instruments just arrived, I am very surprised . I'm pretty sure I can use the (THS4011) it has the same pin out. But I am not to sure about wiring up this one(UC3706N) ???

I have attached the datasheet.

uc3706.pdf

 

[Dazza]

The, THS4011

ths4011.pdf

 

[ante1]

Dazza, Yes, inductors can be paralleled but why do you want to do that? 8) Only a few times have I heard someone having trouble with the magnetic field created around an inductor. This does not mean it can

 

[Dazza]

So here is my disaster, under construction that I have so far . What I'm trying to do is use a 12V battery, with a varying voltage alternator. I am also trying to work out how I can give power, to the reactor from the battery, to produce enough hydrogen for starting the engine. And once started the alternator takes over. There is a lot here that I need to consider. I basically understand how everything needs to interact for this to work. But I am struggling to apply the electronics, to work the way I want :-\. I need to disable both regulators while hydrogen is being produced for start-up, and the current needs to be limited, as to not draw too much current through the two transistors, I have which I'm trying to use to keep the battery isolated from the alternator higher voltage. I will need something that will detect when the motor is running, maybe an RPM sensor so the regulators can then be enabled. I made some modifications to the PWM. I know most of it isn't right, I'm just trying to apply the idea in principle. Clear as mud isn't it ;D ;D

.

View attachment 35922

 

[Dazza]

I added the extra components, to allow me to set the amount of current being drawn from the battery at start-up. And once started it can switch back to the original control. How to make this work properly I'm not sure.

View attachment 35923

 

[ante1]

Mud is the word my friend, ;D on some points I can see what you are aiming for. If you want an indication that the engine has started just use the charge indicator light. This takes no sophisticated electronics to achieve. When the ignition is turned on (see picture) the charge indicator lamp gets positive from the battery and negative through the alternator (not charging). When the engine is

View attachment 35932

 

[ante1]

Dazza, I had a long look at the PWM circuit and there are a couple of things I can

 

[Dazza]

Well ante, I'm pretty hopeless at trying to explain what I mean. I think you're write, make the basic unit and go from their. I'm always looking ahead, for any possible problems I might run into, and I did find one big problem. Having an alternator that I could vary the voltage, and I am using a 12V battery. I didn't think it would be a good idea to be putting 24V into a 12V battery . So the first thing I thought was, how was I going to keep the battery isolated from the higher voltage, as well as keep it charged. Use the second regulator from the LM1458, Q2 will keep the voltage to the battery at 12V maintained by the regulator. Where Q5 is, I had a diode to prevent the higher voltage feeding back to the negative side of the battery. Ok, this seemed to work alright, but there is a problem. To start the engine, I need to supply the PWM with 12V from the battery, and in turn to the reactor, to produce enough hydrogen pressure to start the engine. So now I had to work out a way, to supply 12V to the reactor to start the engine, and then once started, the reactor needed to be supplied its current and voltage from the alternator which is at a higher voltage.

Hopefully you are with me so far, and I'm not just piling on the mud . The purpose of the extra voltage divider in the PWM, is so I can limit the maximum current, being drawn from the battery, and through the diode, which is
labelled with just a (D) Stupid me. This is to be only used at start-up. Q5 and of course, stupid me again Q5. Are used as switches,and the wires going nowhere, will need to go to a device to initiate the switching, that knows the engine is started, and the current and voltage is now being drawn from the alternator.

Now having got this far, and adding components to the schematics and taking them away, and making a big mess. I was still focused on what I was trying to achieve. I now have a problem with the diode, that I had in place of Q5 of the regulator, I didn't have a complete circuit, so I replaced it with a transistor. Now I could add it to the 12V regulator, although I am unsure if it can handle controlling two transistors. Or add it to the device that will control the switching, along with the transistors of the PWM. So Q5 of the regulator can be switched on at start-up, and then switched off once the alternator takes over. Now I just realised, that switching Q5 off of the 12V regulator, will result in not having a circuit I think. Will the regulator on the 12V side, be able to work controlling both positive and negative side of the battery.

Now the wires that I have added to the regulator (W3) are both meant to be going to, pin 2 and pin 6 of the regulators, pretend that they are not there, I don't know what I was thinking.

ante, I hope you like a challenge. The challenge is, understanding what the H**L I'm talking about. Not the actual making a circuit work the way I want. ;D ;D

 

[ante1]

Dazza, There is nothing wrong with looking ahead, but it

 

[Dazza]

Yes ante, I got started on a block diagram today that is something I probably should have done from the start. Then you'll have a better idea of the big picture, and how everything needs to interact. Instead of me asking you to help me set this system up, only knowing half of it. Well ante I have never had to put anything down on paper, before putting it altogether, and I have been involved in construction of all sorts of things, from building trailers to carry 4D dozer to a light boat trailer and farm implements even an experimental Cain harvester. To construct such machinery and make it work the way it should, for me isn't too difficult, I'm able to visualise the entire system and no how it should work, and then just go ahead and put it together. So putting my ideas down on paper, and trying to explain it to someone half a world away, is something new to me. Ok step 1 is right. 2 as soon as the engine is running, engaged the 24V supplied from the alternator, with PWM control, to power the reactor. No I don't need varying voltage. I would just like to be able to set the voltage.Say I want 17V, I can then set the regulator to that, and run the reactor, and then compare its performance with other voltage, combinations of different catalyst, more and less catalyst different electrode spacing and so on. And of course trying to produce as much hydrogen with as little current as possible. Having to use higher current, would probably mean having two use, a larger engine in a smaller vehicle. To still maintain the performance of the vehicle, and also be able to run the reactor. Who cares when the fuel is free ;D. I would really like to try to avoid using two alternator's. I picked up and 85A alternator from the wreckers cheap that needs new Barings. The really isn't much room on the stator, to use heavier gauge wire. I'm hoping to pick up a larger alternator, physically larger that is, maybe from a truck or something like that, that I can get heavier gauge wire in, to produce the higher current that I am likely to need. Yes building it in module form, is a good idea ante.

I will post the block diagram soon ;D.

 

[ante1]

Under normal circumstances I have no problems reading peoples minds when someone is visualising stuff but in this case the distance between us is too big. ;D ;D OK, so constant voltage but with the option to be able to change it. We have to establish in which range you like to change the voltage f ex (12

 

[Dazza]

Ante, can you make sense, of this block diagram.

View attachment 35944

 

[ante1]

Dazza,

This is a good overview to start from.
I have been thinking about the variable voltage alternator, you can have some unwanted effects form a setup like that. It will be sensitive to which rpm it runs at since there is no battery for

 

[Dazza]

Yes ante, I am at a bit of a loss, on how to tackle this problem. If we were to add a large capacitor, we would be asking it to do the job, of a battery. I am thinking that this will be a capacitor of very high capacitance very expensive. Would a recycled capacitor. from a microwave be able to be used, what do you think I could be doing here ante? Yes ante, I can see your catch 22 scenario. There is something that I have left out of the block diagram, that will help (lessen some) of these problems. A device between the pressure sender unit, and the adjust pulse width 12V to 24V. the idea of this device is to (dampen) the possibly fast reaction of the pressure sender, if pressure was to drop dramatically, because of demand from the engine for the hydrogen. So the dampening effect is needed, to lessen the demand on the rest of the system, to respond so quickly. now implementing this dampening effect, will mean there isn't adequate hydrogen to supply the engine. So to fix this problem, a small storage chamber, immediately after the reactor chamber, to hold enough hydrogen for these extreme demand hydrogen fuel situation. For example a vehicle towing a heavy trailer, overtaking a vehicle up hill. This hydrogen chamber, I believe will not need to be much larger, than the supply line itself. Therefore not being a significant storage risk. Now that being said, I do fear using higher voltage, could result in the possibility of arcing, within the hydrogen chamber of the reactor, if the separation of hydrogen and oxygen is less than perfect. So I need to apply caution here, the water will have an additive to it to make it more conductive, and the higher the voltage,the more opportunity there is, for a spark to jump between the electrode, and in respect of the electrode spacing. If I could be sure, that there was only hydrogen within this part of the chamber than a spark would not result in ignition. Now realising this possible risk, in using higher voltage, I feel that the maximum of 24V, should keep me safe.

Now am I understanding this right ante. I have a 12V alternator I am wanting it to produce upwards to 24V. so to achieve the higher voltage. I will be compromising the amperage output. Now this is in respect of the number of windings, within the alternator stater, which will ultimately limit my voltage output. I have read on the Internet that 110V is quite possible, with of course the compromise of the amperage output. So if I was to discover the ideal voltage for this system, to be say 17V. I could then modify the alternator, to be ideally suited for this situation in respect of, the thickness of the wire, to the amount of turns required, and of course the RPM the alternator will require. ante, the information in the link you provided, will prove to be very useful in this project.

I was surprised to find myself in the top 15 post. I would say you would have hit the 1000 post by now ante, my question is, do you get to choose the colour of that free LED ;D ;D.

 

[ante1]

Dazza, Yes a big cap is expensive and a microwave cap is rated for high voltage but it

 

[audioguru2]

Hi Ante,
Your prize will make "only" 16M colours, and its white will be much better than a white LED.