Rangehood Fan and Light

The Swift Rangehood works well, with a vent piped to the roof of the van. But it used a power-hungry 20 W halogen downlight and noisy blower fan.

I replaced the light with a 3 W LED type (see LED Lights page).

Taming the fan required a bit more work

Variable Speed Fan

To reduce the noise, I have made the fan speed adjustable. Full speed is not always necessary. The best way to do this is to use a Pulse Width Modulation controller rather than a power resistor since a PWM controller saves both battery current and heat.

DSE had a PWM speed controller kit K3072. It is no longer available, but Jaycar has a similar, though more expensive, kit (Cat. No. KC-5225).

The DSE kit is easy to make, and needs no heat sinks for the Swift fan (0.66A). I replaced the 5 kΩ trimmer pot with a 5 kΩ logarithmic (A) taper potentiometer type R7516 in series with a 1.5 kΩ resistor on fly leads to mount near the fan switch. The resistor limits the low speed setting to something usable. Now the fan can be adjusted to slow speeds to reduce noise and current consumption (down to 0.3A), though there is then some slight interference on AM radio.

A couple of pics show the speed adjuster next to the fan switch, and the circuit board installed in a clear plastic box in the hood in amongst the wiring (the motor back-emf quenching bits are shown in another pic, mounted close to the fan).

LINKS

• A'van http://www.avan.com.au
• DSE http://www.dse.com.au
• Jaycar http://www.jaycar.com.au

The Swift Rangehood

The rangehood with LED light and fan speed controller.

The PWM motor speed controller is in a clear plastic box mounted within the rangehood amongst the wiring.

A fast acting diode and capacitor wired across the fan motor to quench back-emf spikes.