RPM Meter Kit for Homemade Wind Generators

RPM Meter Kit for wind generators consists of a small PCB, pre-programmed controller, 
and a few discrete parts.  Size is approximately 1.25 x 1.0 inches. It is made to provide a voltage output for the RPM.  You provide a digital voltmeter or analog meter for the display of the RPM.  A PCB and all the parts are provided for you to assemble.  There is also a preassembled version available with wire stubs for all the connections.

This RPM Meter provides the following features:

1.  RPM Meter Voltage Output: 0 - 5Vdc  output represents 0 - 500 rpm for Wind Genny.
Output Impedance = 10K, you can scale the output with a resistor load option for analog meters, data acquistion equipment, etc.
2.  Phase Input:  12V to 48V generator phase input compatible.  Will tolerate outputs above 72Vrms.  Higher Input voltage compatibility is available upon request.
3.  Power Input - Requires 9V - 16Vdc.  Nominal current is ~ 15mA
4.  LED Indicator - Provides brightness corresponding to RPM.  Also used for setting the # poles in generator.
5.  Pushbutton - Pressing the push button allows selecting the # of poles in the generator.  This is needed for the RPM calculation.  Pushing the button for about a couple seconds steps thru to the next poles setting:  4 -> 6 -> 8 -> 10 -> 12 -> 14 -> 16 -> 18 -> 20 -> 22 -> 24 -> back to 4
6.   EEPROM remembers pole setting after power removal
7.  LED blinks current pole # setting at power up and when the value is changed by pressing the pushbutton.

The RPM Meter measures and displays the RPM of a wind generator based on the AC output of one of the phases of the generator.  The RPM meter must be programmed with the number of magnetic poles used in the generator construction to calculate the RPM of the wind generator.  The meter operates by counting AC cycles over a certain period.  The output is generated with a PWM type signal and a low pass filter to smooth it to a DC level the volt meter will read.  Set your meter to measure DC volts when using it for a display.
The meter will not read right until there is about 5V AC on the phase input.

Programming the RPM Meter 

Pressing the push button for a few seconds allows selecting the # of poles in the generator. This is needed for the RPM calculation. Pushing the button for about a second steps thru to the next poles setting: 4 -> 6 -> 8 -> 10 -> 12 -> 14 -> 16 -> 18 -> 20 -> 22 -> 24 -> back to 4.  Once a new pole selection is made, the LED on the board will blink out a count equivalent to the new setting.   The LED will also blink this value when power is first applied.
The PCB silkscreen has labels for all the parts as well as values for the resistors.  You will need a digital multimeter, soldering iron, and solder to assemble the board.  I will provide some more assembly info within the next week.
Parts List:
1 - PCB
2 - 10uF caps - C3, C5 - Note: C5 doesn't have polarity marks, the positive leg of the cap should go closest to C3 cap.  It connects to the RPM+ mounting hole. Verify orientation with drawing before soldering! Power filtering, RPM output low pass filtering.
1 - 0.1uF cap - C1 - color blue. While not polarized, verify they go in right location. uC decoupling.
1 - 0.01pf cap - C4 - color yellow. While not polarized, verify they go in right location.  Filter cap for phase input.
1 - LED - D3 - verify orientation with drawing before soldering! Long lead goes away from silksceen cathode bar.
1 - 78L05 regulator - IC3 - align body with silkscreen.  Power for processor.
2 - 10K resistors -- R2, R4 - verify all resistors with DMM before installing.  Output impedance of RPM output.
1 - 220 - 330 ohm resistor - R1 - for LED
1 - 100K resistor - R8 - input impedance for phase input
2 - 1N4148 diodes - D4, D1 - match bar on diode with silkscreen bar marking. Clamping for phase input.
1 - 8 pin socket - Goes in IC1 location.
1 - PIC12F675 processor, pre-programmed, plugs into socket.  Verify pins are lined up with socket before pressing down.
All input and outputs silkscreened and solder holes for attaching wires.


Please ensure the wind generator is disabled before installing the RPM meter.

Please connect the RPM meter kit up in the following order:

1.  Bat - : Connect to Ground
2.  Bat +: Connect to 9V - 15VDC
3.  PHASE: Connect to any Wind Genny Phase Output
4.  RPM +: Connect to Vin of your meter
5.  GND -:  Connect to GND of your meter

With power applied, program the # of Magnetic Poles in the generator by pressing the pushbutton as described above until the  # of LED blinks matches your generator configuration.  The RPM output should begin tracking within a few seconds.

Schematic Diagram:

Connection Diagram:

Ordering Information:

I am NOT selling these on my other website: http://www.mydtcstore.com anymore, but I am providing the source PCB files and SW to anyone that wants to try to make one themselves. Email me at smith100griggs@gmail.com and I will send you a zip file with the gerbers, schematic and layout files and the PIC SW.  I use www.batchpcb.com for single prototype PCBs like this. 

Here are links to the source files:

PCB files:


PIC SW files:


From there its up to you.

Thanks for looking. 

Contact: smith100griggs@gmail.com
  for more information or questions.