Hi

I am looking to put a variable resistor on my car's pump for the windscreen water nozzles.
Currently they spray water too high.
They are the unadjustable type and replacements are expensive.

I am fairly handy but my knowledge of electronics is pretty much nil. I can splice or add something in but I don't know where to start.
I was hoping someone could advise or had a link to a guide maybe to start me off?

Could I add one inbetween the fuse for the pump?

Thanks,

 

Welcome to AAC!

I am looking to put a variable resistor on my car's pump for the windscreen water nozzles.
Currently they spray water too high.

Using a variable resistor in series with a motor/pump to control it is almost always the wrong thing to do.

A better solution is to use PWM (Pulse Width Modulation) to vary the duty cycle (time the motor is on). This gives the motor/pump full voltage so it's more likely to operate as designed.

 

Hi

I am looking to put a variable resistor on my car's pump for the windscreen water nozzles.
Currently they spray water too high.
They are the unadjustable type and replacements are expensive.

I am fairly handy but my knowledge of electronics is pretty much nil. I can splice or add something in but I don't know where to start.
I was hoping someone could advise or had a link to a guide maybe to start me off?

Could I add one inbetween the fuse for the pump?

Thanks,

It depends on the amount of current the motor takes. Any resistor used is going to have to dissipate a lot of heat. You could even try one or two 5A-10A rectifiers. They will still get hot if you run the pump for too long.

 

@carrepair84 If you don't want pump pressure to be variable, @MrChips solution will work. Insert a fixed voltage drop between the fuse and pump and you'll be good to go.

Each rectifier will drop voltage about a volt. Make sure they can handle the current. The common 1N400x rectifiers are only good for 1A continuous; much higher for very short periods (much shorter than you'll run the pump).

You'll have to determine the voltage drop you need by trial and error.

If you use resistors, you need to derate their power dissipation spec to account for the potentially high operating temperatures under the hood.

PWM is still a more elegant solution. Even if you don't want pressure to be variable.

 

Drill out the nozzle a bit - it will give you more water flow at lower pressure.

 

Those motors typically draw up to 5A of current, so a PWM circuit, as suggested, would likely be the best way to control the motor's speed (example).

 

Aside from drilling the Nozzles to a larger hole size,
( which involves the use of a precision Numbered-Drill-Bit-Set, or possibly a Torch-Tip-Cleaner-Set ),
You may want to consider going to the local Junk-Yard and
selecting a Third Nozzle from a trashed Car or Truck,
there are a million different designs that might be adapted to your Car
and having a third Nozzle will also increase the squirter coverage of the Windshield.
.
.
.