Some of you know about the Vortex Fans made by Heng's Industries. On model of the fan is an upgrade kit; designed as Upgrade/Replacement fan "modules" for various brand fans, including select fans from Jensen and Ventline. There are two versions of the Vortex fan; Vortex I and Vortex II. The difference is the Vortex I version is a single speed fan with a simple On/Off switch. The Vortex II includes a 3 speed switch along with Forward and Reverse directions.

Both fans have the same frame and fan motor, with the only difference being the controller. A popular modification RV owner's do is to purchase the less expensive Vortex I, then add an Amazon/eBay PWM (Pulse Width Modulation) speed controller to provide a better controller than the one that comes with the Vortex II; which is simply a couple of big resistors and a switch on a circuit board.

Well the brain-trust here at RV-Project.Com is not satisfied with just adding a speed controller. Oh no. We have to go overboard like we usually do. We are not only going to add a PWM speed controller, but we are also adding a wireless remote control and a timeout delay so we can have the fan automatically shut down after 1, 2, or more hours. And as always, you can build such a controller as we will provide all of the details necessary to do so.

So, you really have two options in modifying a Vortex I. Either a commercially available PWM controller, or custom building RV-Project's version.

If you want to use the commercial version, it's easy. I will not be doing a video on it, but I will be providing the instructions necessary to do so. Since the top side of the fan is exposed to the weather when the vent is open, I highly recommend buying the version that can be put into an enclosure, and/or at least spraying the circuit board with conformal coating.

Connecting these boards is easy. Two wires go to the 12V Supply and two wires to the fan motor, and you are done.

In order to understand how the remote control works, it is useful to look at a block diagram as shown here. The Motor driver is a Texas Instruments DRV8871 DC Motor Driver, capable of controlling motors up to around 3Amps. Testing has revealed that the motor has the following current requirements:

• Start Up: 2Amps
• Full Speed Operation: 1.2Amps

Therefore, the 3A capability of the DRV8871 is more than sufficient to control our fan. The DRV8871 is controlled by an Atmel ATTiny85 microcontroller, which outputs either a logic HIGH (5V) for full speed operation, or a PWM (pulsed output) for lower speeds. The controller also has a brake circuit which can be achieved by driving both outputs a logic LOW (0V). The ATTiny85 also provides the timeout function.

Programming of the ATTiny85 is necesary, but it is easy for this project as no libraries need to be installed. Simply upload the sketch (what Arduino calls a program), and you are finished. The sketch can be downloaded with the icon to the right.

Save the sketch in your Arduino IDE folder (see instructions at the "Setting up the IDE" link below).

The power supply provides 5V to the ATTiny85 and Receiver, while 12V for the motor comes directly from the RV's 12V system. Note that the On-Off switch (Local-Off-Remote) turns the receiver on in Remote mode only.

Also, if you need a tutorial on setting up your computer to program the ATTiny85, I have a page and video dedicated to just that need at the link below:

A PDF build file exists that details all of the parts placement on the circuit board as well as wiring to the fan and any necessary modifications required to the fan base. You can download the build file by clicking on the Icon on the right.

The PDF instruction file, this webpage, and associated videos collectively describe the project.

This material is presented in accordance with copywite by Creative Commons 4.0 and may be used for private, non-commercial pusposes only.

You will also need some hook-up wire (18AWG), M2 hardware and standoffs, rubber grommets, RTV, and other miscellaneous items. Often it is less expensive and easier to buy parts kits such as the examples shown below that include enough parts for several projects.

One special resistor on the circuit board is the ILIM Programming resistor. The ILIM pin on the DRV8871 Motor Controller has an option to enable as current limiting resistor. This is useful to keep the current to safe levels should the motor stall, a short occur, or other catastrophic event. The current limiting resistor is determied by the formula here:

While the formula may seem a bit daunting, it can essentially be resolved into: I(Amps) = 64/ R(KOhms). For example, using a 20K resistor, the maximum current would be 3.2A (64/20=3.2). If current limiting is not required, a 15K ohm resistor must be used on the ILIM pin. The chart below provides values for common maximum current limits:

When purchasing the receiver, note that there are two types that are almost identical. They both work fine, but the difference is the footprint of the receiver. This project uses Type B because it's footprint fits into the available board space a bit easier.

However, it is a bit harder to source than Type A receivers. If you cannot find a Type B (or ordered a Type A by mistake), there is an available adapter board that will allow a Type A receiver to fit onto the board.

Before you can use the receiver, you need to set it up properly. Typically, these receivers come setup in the Latching mode, and Channel 1 on the receiver corresponds to Channel 1 on the Transmitter, and so on. There are three steps required anytime you need to re-program the recever. Note that in Steps 1 and 2, you depress and hold the receiver button Before you turn on power to the receiver. In Step 3, you depress the receiver button After turning on power. Also, Step 3 is a multiple pass process (pass 1 for RX Channel 1, pass 2 for RX Channel 2, etc).

Step 1 clears the current programming. This clears the Mode as well as all of the transmitter button mappings.

Step 2 sets the receiver into Momentary mode.

Step 3 assigns each transmitter button to a particular channel. You can assign any transmitter button to any receiver channel, as well as assigning all of the transmitter buttons to a single channel (you can assign about 50 transmitter buttons to any receiver channel, if you need support for multiple transmitters).

Also realize that in Pass 2 thru 4, the receiver button will blink once, then twice, then three times, then four times - depending on how long you keep the button depressed. Simply release the receiver button After the LED blinks the appropriate number of times.

There is also a timeout of a few seconds. After you release the receiver button, you have several seconds to depress the appropriate transmitter button. If no button is depressed, a timeout occurs and no button mapping will be set.

If you make a mistake in mis-assigning transmitter buttons - say you assigned transmit button 3 to receiver channel 2 when you intended to assign it to receiver channel 3 - you must start completely over. That means, return to Step 1 and clear the programming, Step 2 and set the mode, then Step 3 and program each receiver channel.

You can do Steps 2 and 3 in reverse order - i.e. perform Step 3 first, then Step 2. Also, you can do Step 3 multiple times. Say you map all of the buttons of a transmitter to the receiver, then later want to map a different transmitter... just perform Step 3 again.

References:

DRV8871A Datasheet
Vortex Installation Instructions
TL-2 Staking Tool