Examples of three different PWM duty cycles

Pulse Width Modulation

Our Infinitybox System is far different from a traditional fuse & relay based wire harness.  There are things that Infinitybox can do that you couldn’t even begin to imagine with a good-old bundle of wire.  One of our biggest goals when we educate people about our products is to de-mystify some of the potentially scary terms that we use.  One that we use a lot is Pulse Width Modulation or PWM.  This is a fancy term for turning something on and off very fast to control power.

We don’t use relays in our POWERCELLs.  Instead, we use MOSFETs.  Yes, I know that is another scary term that we’ll talk about later.  For now, all you need to know is that MOSFETs are solid state stitches.  Unlike relays, there are no mechanical parts in them.  You can turn a MOSFET on and off literally millions of times per second.  You can do that with a relay 2 to 3 times per second before you have to worry about burning up the contacts.

The ability to turn a MOSFET on and off very quickly allows us to control the amount of power coming out of a POWERCELL output.  We do this by using something called Pulse Width Modulation.  PWM is the process of turning an output on and off quickly.  The effective power coming out of the output is proportional to the amount of on time as compared to the off time.  The ratio of the on time versus the off time is called the duty cycle.  So for example, if we turn the output on for half of the cycle time and off for the other half, your duty cycle is 50%.  The effective voltage of your output is approximately 50%.  This picture shows you what we mean.

Examples of three different PWM duty cycles

Examples of three different PWM duty cycles

The three different graphs are 10%, 50% and 90% duty cycle.

Check out this video showing you more about PWM.  If you haven’t seen Colin’s Lab on You Tube before, it is a worthwhile watch.  He is a geek’s geek but makes great videos explaining the basics of electronics.  As part of Make Magazine, his stuff is filled with tons of useful electronics projects, tips and tricks.

So you’re asking yourself, “What does this mean to me”?  “I’m wiring a car, not building circuits.”  Pulse Width Modulation is a very effective and efficient way to control the brightness of lights and the speed of motors.  There is very little heat lost with PWM as compared to using resistors or rheostats.

The Infinitybox system has PWM capability built into the POWERCELL outputs.  We can effortlessly dim lights, create daytime running lights, theater dim interior lights, control fan speeds, and fuel pump speeds.  For those who need that advanced control, it is built right into your system.  No external modules or hardware are required.

Click on this link to contact one of our technical support guys to talk about your specific requirements using Pulse Width Modulation.

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  1. […] Our Infinitybox system has an added feature that you can’t get from a relay.  Since we are using MOSFETs, we can do something called Pulse Width Modulation or PWM.  This lets us turn the POWERCELL outputs on and off thousands of times each second.  Using PWM lets us efficiently control the flow of current from a POWERCELL output.  For fans, we do something called soft-starting.  This lets us gradually ramp up the current to the fan to smooth out the in-rush current.  We’ve blogged about this before.  You can read it here.   […]

  2. […] The POWERCELL is a remote fuse and solid-state relay box.  The fuses that you need to properly protect your wiring harness are built into the POWERCELL.  You do not need to add separate fuses.  Also, the solid-state relays that control your loads are built into the POWERCELL.  Each output can carry up to 25-amps continuously so you do not need to add external relays to control your lights, fans, pumps and other accessories.  Also, we don’t use mechanical relays in our POWERCELLs.  Our outputs are controlled by solid-state MOSFETs.  This are rugged and reliable and give you tons of benefits over traditional relays.  Check out this link to learn about some of the advantages of a MOSFET. […]

  3. […] Their core products are designed for returnless fuel systems.  There is only one fuel line going from the in-tank pump to your fuel rail.  There is no fuel regulator on the rail and no return line that brings excess fuel back to the tank.  Their Fuel Pump Controller mounts in the rear of the car, near the fuel pump.  It actively monitors the fuel pressure in the line at the outlet of the pump.  Using pulse-width modulation (PWM), they vary the pump power to keep the fuel pressure within a tight window.  This reduces dead-heading of the fuel pump and also reduces the amount that the fuel gets heated.  We use PWM to control things like fan speed and light dimming from our POWERCELLs and have blogged about how that works before.  Click on this link to learn more about PWM. […]

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