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Schematics Variable current 12v 60A to 0A


Dazza
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Yes ante, I did notice the mistake on the regulator. I am sure you just done that to test me ;D. I noticed it when I thought of changing it to an adjustable regulator. I also thought of using diodes to drop the voltage, I strung a few of them together to see how much the voltage would drop, then I thought it may be a bit of a rough way to go. It tells me on the datasheet for the(AD8061) that it is not a good idea, to run it at maximum voltage for long periods of time. Maybe the modifications that I made, will work OK what do you think. I also changed the power supply to the (ICL7667) should this work OK, I was thinking that I may need to experiment with higher voltage, so I will also have to consider the voltage ratings of the capacitors. Now I don't know if this will work or even if I need to do it, if I was to add a diode from the 9 V supply, and a diode from the 5 V supply and joined the 9v and the 5v together, this would give me 11.8V, to supply voltage to the(ICL7667) as to not upset things too much. So basically your circuit is still functioning as it had originally did, in respect to power supply. We've just improved it with a better amplifier and supply the amplifier with its ideal voltage :).%7Boption%7D

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Hi Dazza,
Are you going to use an ICL7667 driver from Farnell? Good. It needs only a 0.8V to 2.0V TTL input voltage (but can take much more), and your AD8061 opamp used as a comparator is fully spec'd for a 5V TTL supply. So why not just use a 78L05 5V regulator for the AD8061?
The AD8061 works with input voltages from 0V to only 3.2V when using a 5V supply, so those input voltages should be reduced by adding a resistor to ground at its pin3, and changes to the adjustable reference (PWM control) voltage at pin2.

Hi Ante,
I don't like the D3 and D9 zeners which appear to feed positive load spikes directly into the outputs of the ICL7667. Since the ICL7667 has such a low output impedance, I think that the little D6 and D10 will blow first.
All that D5/7 and D8 are going to do is to add capacitance to the gates (and we don't need it).
Therefore let's get rid of all those zeners and diodes.
Most power Mosfets have a huge zener (and its reverse-bias diode) from drain to source.

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Hi Ante,
Soon I'll be huntimg for Mosfets and I'll let you know how I decided on one. My catalog has about 1000 Mosfets and the price list is separate from the spec's. Therefore it will be difficult to choose.
I will probably make a list of Mosfets that have the spec's that I need, and when I see their prices then I'll compromise the spec's, and then I'll select the cheapest one. I'll probably end up using more paralleled cheap mosfets than I originally planned.

The "supply line filtering must be increased" for the ICL7667 because it will draw high current pulses from the supply when it quickly charges and discharges the total high capacitance of the gates of multiple Mosfets. Plus the few-hundred mA current pulses that it draws though itself during switching.

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audioguru, yes I will be getting the components from Farnell. The MOSFETs (FDP7030L) is 100A 30V, this is what it is listed as, in Farnell CD catalogue. And on the datasheet I have ???.

ante, I'm just trying to get as much flexibility as I can. If I needed to experiment with voltage up to 24V it would be good, to not have to come back and modify the circuit. So a 5V regulator to supply(NE555N) and the(AD8061) so what would be best to use for (ICL7667) a 9V would give me a little headroom, considering my supply voltage is 12V or would it not matter, using a 12V regulator ???.

The voltage supplies the path for the current to flow through the water, this makes sense to me, this is why I'm thinking I may need to experiment with higher voltage. Does this sound right to you.

The components surrounding IC2 and IC4, are they going to be affected, now that they are being supplied 5V ???.

The regulator for(ICL7667) what should its current rating be.

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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

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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%7Boption%7D. I still have two consider the pin out, for the regulator's.

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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

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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.

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So here is my disaster, under construction that I have so far :o. 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%7Boption%7D.

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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

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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 :o. 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

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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.

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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

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