The KZX1250 has been designed with the needs of the HHO enthusiast in mind. Nothing was overlooked or compromised. It had to have everything from being tiny, cool, safe and easy to install to being robust and able to perform and survive regardless of its environment. With the KZX1250, you won't have to buy any other expensive components that when added on to your "budget PWM", ends up costing you a lot more; especially in the long run.

Already bought a PWM? Bookmark the order page for when your PWM burns out. Don't dump more money into it on MOSFET's and definitely don't buy another!

Why the KZX1250?

We have found through extensive research that many problems surface when setting up your vehicle for an HHO installation. Not only choosing the right cell configuration and size, but your method of powering it.

Many experimenters know that the PWM needs to have the ability to automatically regulate current to avoid thermal runaway, but there are many other issues that come up when making your install and they take a lot of your time and patience with them. These issues have plagued many for a long time and led to the design of the KZX1250.

Power on/off

The PWM must have a fool-proof way of starting up. You don't want to have to start it with a switch every time you drive because you are bound to forget to turn it off and that can be dangerous. Some have tapped into their oil pressure sensor so it will only turn on when the engine is running. Others have tapped into their ignition as their method of choice. Both of these methods require a high current relay as the circuits being tapped into cannot supply the high currents necessary to power the PWM. High current relays are prone to arcing when switching on and off unless a snubber circuit is used; but without such a snubber circuit, the arcing will cause pitting on the contacts and will eventually fail. Sometimes the contacts get so hot from this arcing that they actually weld themselves together. Both of these methods also require modifying existing circuits that are part of your vehicles electrical system which can void the vehicles warranty and can confuse a mechanic who is working on your vehicle. These setups also have other faults. For instance, if the battery is very weak, the PWM will still deliver current to the cell; further weakening the battery. If the ignition is tapped into, the PWM will also come on when the key is in the ACC position. You might remember not to use the ACC position, but someone who borrows your vehicle won't.

The KZX1250 solves all of these problems by having the unique ability of sensing when the engine is running and when it is not by monitoring the charge voltage and only turning on when the alternator is supplying power to the system. The ability for it to do this does not depend on modifying existing circuitry or requiring the use of a high current relay. If the battery is weak, the KZX1250 will shut down completely. The KZX1250 is in complete control of turning the unit on and off so that you don't have to worry about if it should be on or not.

If you have used another PWM that controls the power by sensing the system voltage and you didn't like how it worked, it's probably because of its improper implementation. The KZX1250 works perfectly every time.

Current Monitoring

Along with installing a PWM to power your cell, you will also need to measure the current going to the cell. This is important to allow you to adjust your PWM properly and should be available any time to check the status when you maintain your system. Many have purchased these separately and had to find a way of mounting them somewhere in the vehicle or under the hood. An ammeter is so important when using a PWM that we felt it was a must to make it an integral part of the KZX1250.

Fire Safety

The powering method chosen must be safe to use in your vehicle. Since a typical high current PWM can get pretty hot, it can be a fire hazard. I have seen that many have installed their PWM in the interior of their vehicle; particularly in the dashboard. This poses a serious safety issue because in the event that the PWM catches fire while driving on the highway, there really is no easy way to bring the situation under control. Once it starts burning and filling your vehicle with smoke, you can't easily toss it out the window because it is bolted down and attached to heavy gauge wire. If it should burn up, your only alternative is to open the windows, pull over, get out and watch it burn (unless you have a fire extinguisher).


However, installing the PWM under the hood means that it will have to be water resistant to resist sprays of water that will cause the electronics to fail. You can't really create a water-tight enclosure because the PWM gets hot and needs to breath. If you sealed it in an air tight enclosure, the air pressure inside would build up as the temperature increased and blow out the gaskets or could even blow the housing apart. This means that the electronics needs to be conformally coated and the housing needs to be able to breath; not just to release pressure, but to allow it to drain any moisture that will precipitate inside the housing.

Making the KZX1250 water resistant so it could be installed under the hood, was one of its first specifications. Not that the KZX1250 is prone to burning up, but that electronics in general could fail so all precautions should be taken. In fact, the KZX1250 is less likely to burn up than other PWM's for many reasons. For one, it runs a lot cooler than other PWM's we have seen and it doesn't have a heat sink that gets red hot. Secondly, it has thermal protection built in that monitors the temperature of the MOSFET's and will turn them off immediately if the temperature should rise above its normal operating temperature (which is well below the MOSFET's upper temperature limit). This might not seem to be a big deal until you think about the possibilities. For instance, what happens if the fan burns out? Most PWM's wouldn't notice. They would just happily deliver the requested current until the MOSFET's burned up. The KZX1250 would just flag it as an error condition as soon as the temperature of the MOSFET's increased above its allowed temperature and turn the MOSFET's off. Of course that upper temperature would only be reached if the KZX1250 was drawing a significant amount of current with a dead fan. Another thing most people won't realize right away is that they mounted their unit in a very hot spot under the hood. It may seem like a cool spot, but when the hood is down, hot air currents from the engine could be directed right at it.

If you were to get into a serious head on collision and you are knocked unconscious, your engine would stall, what about your PWM? If it is connected to the ignition, it will still operate, producing dangerous hydroxy vapors which can turn a bad situation into a catastrophe! The KZX1250 would just turn off.

Short Circuit/Overload Protection

Most PWM's that are sold for HHO don't have their own circuit protection. The vendor will tell you that you must install a fuse in line with your cell to protect the PWM from overloads and short circuits. Installing a high current fuse in line with your cell is a must no matter what PWM you use; the KZX1250 is no exception. The reason why you need a high current fuse is not to protect the PWM, but to prevent a fire from breaking out if the electronics should fail for any reason. If you modestly exceed the rated current of the fuse (dialing the current too high or adding a little too much electrolyte, then the fuse can protect the PWM; but if there is a short circuit, the MOSFET's in the PWM will be damaged. You might not notice this right away because there usually isn't any visible signs and the units still might work, but the damage is there internally. The MOSFET's on resistance (known as RDSon) will increase slightly as the channel has been slightly cooked. The MOSFET will usually still function, but because of the increased resistance, it will get hotter than it did when you first purchased it and will eventually fail.

Automotive fuses are designed to prevent your vehicles wiring harness from turning into a toaster or more specifically, to prevent lawsuits. They were never designed to save electronics. In fact, there really isn't much of an incentive to guard the consumer from having to re-buy an electronic product. So the PWM is not really protected and since a cell is just a bunch of electrodes spaced a fraction of an inch apart and uses a conductive electrolyte to increase current, short circuits and overloads are very common. 

We felt that a PWM should be durable enough to survive whatever the application is bound to face. After all, if you have to keep replacing fuses, MOSFET's and complete PWM's, it could add up to a lot of wasted money and time; defeating the purpose of installing the system in the first place. Since fuses open by burning up when the temperature of the filament rises to a specified level, they are extremely slow in breaking the circuit. They take as much as 100 ms (one tenth of a second) to open after passing their rated current. This is because electric current moves a lot faster than heat and so they could have hundreds of amps of current go through them for a short time before they actually break the circuit. The same heat that burned the filament in the fuse is the same heat that the MOSFET sees; in fact, the MOSFET sees even more heat because it has a higher resistance than the fuse and thus has a higher IR drop.


The KZX1250 has its own circuit breaker mechanism built in. Unlike fuses, this breaker mechanism is triggered by the current itself, not the heat. So the KZX1250 is able to break the circuit long before the MOSFET's even feel the heat. In fact, you can short your cell out with a 5 amp fuse and the KZX1250 will shut down the current before the fuse pops leaving you with an error message telling you there was a short. You can actually try this, over and over and the fuse will never pop. We believe you could probably do this with a lesser value fuse, but we just never tried it before. So the high amp fuse you use in line with your cell will never pop, unless the KZX1250 were to fail.

Some people have added an off the shelf circuit breaker to their system with the false belief that it will protect their PWM. While it will save them from having to replace fuses, they'll still be damaging their MOSFET's, even more so because those circuit breakers are slower than the fuses.

Alternator Protection

One problem we have seen is that if you are pulling large amounts of current from your alternator while idling and you have many other accessories turned on, such as high beams, brake lights, radio, heater/AC blower, radiator fans, etc. The large current draw causes the RPM's to drop significantly because the regulator is saturating the alternator field coils with current to attempt to keep up with the large current demand. This is making it very difficult for the engine to turn as the electromagnetic strength of the alternator is resisting. In some cases if enough current is being drawn, the vehicle could actually stall out. If this happens to you, your first instinct might be to increase the idle speed of the engine a bit so it won't happen again; but this just wastes gas when all those accessories are not on (which is usually most of the time). What makes this happen is that your vehicle was designed to run at a specific RPM. That RPM was chosen to account for the heaviest expected alternator load which is all accessories turned on while idling. It didn't account for another 20 or 30 amps that you are pushing through your cell. The alternator capacity was also chosen to supply enough current to run all your factory accessories and maybe a little extra (certainly not another 30 amps). If you aren't using any accessories, you could actually lower your RPM and save gas, but you shouldn't do this because when you do use the other accessories, your vehicle wouldn't run right.

When you are idling, your alternator cannot output its rated capacity because it just isn't turning fast enough. When you demand too much extra current from the alternator, it can fail; even with as little as 20 amps! The first sign of the alternator being overutilized is when the system voltage drops significantly. Remember, the regulator is designed to supply approximately 14v at all times no matter what accessories you have turned on. If the voltage falls below that, it means that the alternator cannot meet its demands. The lower that voltage gets, the more the alternator has to struggle to output power. You can actually toast the windings or the diodes inside the alternator if current demand is excessive.

Since running your generator at full power puts a serious overall load on the alternator at idle and it really isn't necessary to generate large amounts of hydroxy gas during that time, it makes sense to just back off on the current feeding it when current demand from other accessories is very high. When the vehicle accelerates and the alternator is able to provide its rated capacity, the current can be restored to full capacity to meet demand. The KZX1250 does this by taking a snapshot of the system voltage at idle when the most used accessories are on. This voltage sample is then stored in non-volatile memory and used as a threshold data point. When the system voltage drops below this point, alternator protection takes priority over auto current limiting and the duty cycle will be scaled back until the voltage is restored. This removes the unnecessary load from the alternator at times when it could be overutilized. When you set alternator protection, you are basically telling the computer, "My vehicle runs fine at idle with the accessories I use mostly (which you now have on), when I use more accessories and have been idling for a long time, I want the current to my cell to drop off enough to keep my vehicle idling like it is now and resume when those accessories are turned off or my engine accelerates."

Current Capacity

Many PWM vendors seem to advertise their units by their current capacity. It seems to be an advertising point they want to make that the more amperes the unit can supply, the stronger and longer lasting it is. The truth is that the current capacity has absolutely no bearing on the life expectancy of the PWM. After looking at many of them (and I won't mention their names), I have come to the conclusion that most of them don't deliver the current they promise. Not only because of how they are constructed, but how they expect you to use them.

If a PWM is supposed to be a 55 amp or even a 50 amp PWM, it is supposed to be able to sustain the advertised amperage of 50 or 55 amps. If the unit requires a 50 amp fuse in line (like they expect), it is impossible to reach 55 amps or even 50 amps; because as soon as it does, the fuse pops. If a unit is advertised as a 50 or 55 amp PWM, then it should require a fuse at least a few amps higher than what it is advertised so that when you use it to its full capacity, the fuse won't open on you.

I have seen vendors claiming their PWM outputs 35, 45 and 55 amps. Since there are no fuses rated at these values, you simply have to use the lesser value fuse. If it's a "35 amp unit", you have to use a 30 amp fuse. You obviously cannot reach 35 amps and if you reach even 30 amps the fuse will pop, so you really are limited to somewhat less than 30 amps; perhaps 25. This allows sellers to puff up the current carrying ability because they know you can't possibly reach that value unless you don't use a fuse. And their true current carrying ability is based on a current draw that creates an incredible amount of heat!

Another scheme is that many vendors advertise their PWM's current capacity based on the absolute maximum current limits of the MOSFET. This is quite silly; if we did that, our PWM would be rated at hundreds of amps since there are 8 MOSFETs in parallel. If you read the data sheet for any MOSFET, you will see that attached to the maximum limit is a temperature which is usually 25 degrees centigrade. That means you can pump up to the current limit before the MOSFET burns up as long as the temperature doesn't increase higher than 25 degrees centigrade. Well do you know of any high current PWMs that don't go over 25 degrees centigrade? Most of them run at about 80 degrees centigrade when they are pulling large currents. Even the KZX1250, as cool as it runs doesn't stay below 25 degrees centigrade when it is pushing 50 amps (although it doesn't get anywhere near 80 degrees). And remember, if the temperature of the PWM is 80 degrees, the MOSFETs internally have to be hotter at their junctions (where it counts). With higher temperatures, the absolute maximum limit drops off quite a bit. If the metal casing of a PWM is reaching 80 degrees centigrade, then god knows how hot the MOSFETs inside are getting! Perhaps these PWMs that advertise 100 amps or more are capable of that, but only for a few seconds; until their heat sink or housing gets saturated with heat. Advertising a PWM based on MOSFET absolute maximum ratings is being dishonest to the customer.

Heat is the worst enemy of a MOSFET. Most PWMs have a heat sink attached to the MOSFET and they use through hole components such as a TO-220. Since these MOSFETs are coupled to the heat sink by a simple screw, the heat sink is only effective as far as the tightness of that screw. Over time, these screws can loosen up (especially from hot/cold temperature changes) and if that happens, the heat sink will not be able to cool the MOSFET and the MOSFET will fail. Since there is quite a bit of vibration in a vehicle due to the rotating engine and bumpy roads, it is not unusual for those screws to loosen up eventually; hampering the MOSFETs current capacity.

We felt that through hole components aren't the best choice for the KZX1250. Not just because of their size or the heat sink issue, but because the leads are long which adds to the overall resistance (they get hotter) which we want to reduce as much as possible. They are also quite large, meaning they would take up too much board space and would require a rather large enclosure. Our original prototype used 6 DPAK SMT MOSFETs. Because they are surface mount, the body of them is soldered directly to a heat sink; which is the circuit board. To lower the temperature further, we decided to add two more MOSFET's, but even the DPAKs were too big for the enclosure we wanted to use. So we decided on the PowerPak package which allowed us to install 8 of them. Since these MOSFET's are so small and wafer thin, the little heat they each produce is immediately transferred to the board. Because of the small enclosure and the tiny cavity inside, the small 40 mm fan was more than enough to expel any heat the MOSFETs would give off. It ran so unbelievably cool even at 50 amps with frequency at maximum. No other PWM that we have seen could even come close to how cool the KZX1250 runs. You can actually squeeze the board between your thumb and index finger while 50 amps is being output and you won't burn your fingers. Try that with other PWM's and you will have blisters!

The KZX1250 is rated to deliver 50 amps to your cell without a hiccup. You could actually dial in up to 55 amps before it will throw an error message and shut down. Electrically, it could deliver much more current, but we don't want to drive the MOSFET's very hard; this is the key to having a unit that will last a long time.

Once again, current capacity has no bearing on how long a unit will last, only how much current it can reasonable sustain without damage (if their rating is correct). For most automotive use, 30 amps is probably the most you'll be able to draw without killing your alternator, unless you have an aftermarket alternator; then you'll be able to go a little higher. The KZX1250 allows you to go as high as 50 amps; which we believe is more than enough current capability for most automotive applications. No matter how much current you draw using the KZX1250, it will never get hot.

Duty Cycle Display

While it might not be extremely important to see the duty cycle, it certainly does help you maintain your cell's electrolyte. What you want to do is put just enough electrolyte in to give you your target current with the duty cycle at or close to 100% when the cell is just started cold and set the unit to auto current mode. This way as your cell temperature rises and the cell demands more current, the duty cycle will drop enough to keep the current steady at your chosen setting. When the cell reaches operating temperature, you should make a note of the duty cycle; this is your reference. For instance, if it drops to say 70%, you know that if it ever goes to 75% after warming up, you know you need to add more electrolyte as evidenced that the PWM has to turn on more to make up for the higher resistance of the fluids. If it goes lower, say 65%, you know the PWM is turning more off than your original reference, so you have too strong a mixture (probably due to water evaporation) and need to dilute it with more distilled water; just adding enough to bring you back to your reference (70% in this case).

We felt that this functionality was important enough to be included in the design of the KZX1250 so it was added as well.

Digital Disable

Setting up a system to be as fail-safe as possible could mean adding additional components to guard against unexpected failures. Just having the ability to switch off the system manually is important enough. You can be faced with other situations depending on what you use for a generator, where you install it and how often you maintain it.

Perhaps you haven't checked your generator in a while and the water level has dropped a bit. Less water in your generator can mean hotter temperatures. Sometimes a water level switch may be useful to turn the PWM off when the water falls below a certain level which you have determined to be unreliable. A water level sensor is good to use to turn off the PWM, but if it is used just to send an alarm in your vehicle to remind you that you need to add water, it could make you reliant on it and less likely to physically check the level. This can be dangerous because the water level sensor can fail and you wouldn't know if you don't check under the hood often enough.

Another thing you can do which is even better is that you can hook up a temperature sensor to your generator to turn the PWM off when excessive temperatures are realized. Not only will the temperature sensor guard against anything else that could cause the temperature to rise, but it will also guard against low water levels. Just make sure that the sensor is connected to the bottom of the cell so that when the water level is low, the sensor will still get a reading.

You can also hook up a gas pressure sensor to your bubbler. What this will do is turn off your PWM in the event that gas pressure is excessive. This however, should not be used in place of a safety blow off value as in the event of a sensor failure, the bubbler would be subject to explosive pressure. If the sensor is selected to be activated before the pressure rises above the mechanical blow off valve pressure, the pressure in the bubbler will be relieved before the blow off valve operates; thus saving you from having to replace the blow off valve.

We felt that some enthusiasts would want to add extra sensors to make their system as a whole as robust as possible. So the KZX1250 was designed to cater to such a crowd by adding a digital disable line which is activated by a ground signal. Since it is ground activated, it uses OR logic to gate the output of the PWM. This means you can hook up as many sensors or switches you want and if any or all of them are activated, your generator will be shut down. The digital control means there is no relay used; it is all solid state which makes it reliable. Relays are rated by the number of times they can be activated before they become mechanically unreliable.

Safety isn't the only thing you can use the digital disable for. You can use it to create a system that regulates the flow of gas depending on how fast the engine is running; similar to a fuel injection system.

Voltage Spike Protection

One thing we don't mention in the features is protection from high voltage spikes that occur randomly in the automotive system. The KZX1250 has a maximum input voltage of 15v. The reason why is because the electronics is protected by among other components, 15v transils which are wired across the main power. These transils protect by becoming short circuits every time there is a voltage spike. There are six transil junctions which can absorb quite a bit of energy. If you were to connect the KZX1250 to a power supply above 15.3v, you would burn out these transils. But there's nothing to worry about if you install it in your 12v vehicle (like you're supposed to), as static voltages will never get that high.

Frequency Control

There are some people who believe that there is some magical frequency that will produce more hydroxy; yet no one seems to make a valid test proving this theory. We have seen videos of people running their cell at a high frequency and showing how their cell shows lots of bubbles, but they never test the flow or the quality of the bubbles. All you see is lots of tiny bubbles. Maybe the higher frequency produces tiny bubbles that make it appear to produce more gas. Maybe those tiny bubbles actually contain less hydroxy. I have yet to witness anyone showing any real evidence of this claim.

Regardless, we felt the need to give the KZX1250 a usable range of frequencies. The range isn't as high as some other PWM's we have seen, but that's because we don't want it to get red hot like the other PWM's. We don't know for sure if certain high frequencies produce more hydroxy and we really haven't seen any evidence to its merit, but what we do know is that the high frequencies produce tremendous amounts of heat in the PWM. Damaging heat that will certainly shorten the life of your MOSFET's.

When I see someone advertising that their one of two MOSFET PWM puts out some ridiculous current, like 150 amps and offers some ridiculous frequency like 100 kHz it makes me roll my eyes at how marketing is being profoundly abused. Maybe it can output 150 amps for several seconds or even a minute or two; big deal! Maybe it can reach 100 kHz. Try reaching 100 kHz with any significant amount of amperage (even 10 amps) and I'm willing to bet that PWM will light up faster than a spark in a balloon full of hydrogen!

The KZX1250 doesn't advertise any gimmicks or hype; just facts. It doesn't need to because it has more usable functionality than any other PWM we have seen; so there is plenty of real important features to discuss that are essential. I have seen many vendors advertise that their unit comes with two large fans or a huge heat sink. How ridiculus is this? They're actually implying that that their PWM creates more heat than any other on the market; and this is something to be proud of? The KZX1250 has no heat sink and I wish I could say that it doesn't have a fan either; that would mean that it creates no heat at all. But in the real world, you can only make a PWM so efficient that it still requires at least some kind of cooling. The KZX1240 only requires one small 40mm fan; which is the smallest fan I have seen being used on an HHO PWM.

From the carefully planned hardware to the intelligent firmware, the KZX1250 is the smart choice for your HHO automotive application. Don't compromise on safety or reliability; it's just not worth it!

Many newcomers make the same mistake when they start looking for a HHO PWM for their automotive application. They assume that any PWM will do and they buy the cheapest one they can get, only to find they are looking for a better one. I have seen people buy 3 or 4 different PWM's and still can't get a reliable system together. Those cheap PWM's are cheap for a reason. They are simple designs that in many ways aren't designed for HHO especially for installation in an automobile. The KZX1250 is expensive for a reason. It has advanced circuitry that took nearly 2 years to completely develop. Usually the cheaper PWM's wind up costing you more, not just because of the additional components you have to purchase (relay, ammeter, etc.) just to make use of it, but in the long run by having to replace burned out parts which always seems to go on and on forever.

If we had asked everyone that wanted a PWM for HHO that would have all the features they needed and fixed most of the problems that come up when putting a system together, wouldn't you want to chip in for the development of such an incredible product? One that is virtually bulletproof and won't let you down at the most inconvenient time? It would have cost you hundreds or even thousands depending on how many of you would be willing to chip in.....but you don't have to do this because the research is already done for you, all you have to do is buy the research, or more specifically a share of the research that went in to development by purchasing the KZX1250.

Why waste your time and money on a sub-par PWM, only to find out you'll be digging deeper into your pocket. Why reinvent the wheel and do research that has already been done and is proven to be effective. Get the complete solution for your cell powering needs. Get the KZX1250.