I bought one of these 5 digit meters for a project unrelated to wind for $10. It reads out RPM to one decimal point (assuming you stay under 10,000rpm) or it can be set up to read frequency. Input is 0-30V or 30-300V selectable by an internal jumper and it has an optional software filter. The readout can be corrected by a multiplier divider setup. I have corrected the instructions to be readable.
http://www.ebay.com/itm/371227294288?_trksid=p2060778.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AITFrequency and RPM Speed Display Setup
NOTE: Disconnect the input signal before setting when the input signal is High level voltage signal (300V)
Open the back cover of the meter,
Press "S2" button (right hand top corner facing the connector on bottom) to enter "SET" mode.
A single number 1 will appear with rest of the digits blank.
This indicates RPM with Filter, factory setting.
If another mode is required, quickly press "S1" button (left hand top corner) to change display mode.
Setup reverts to normal display in a short time, only 10 seconds.
The options are as follows:
"0" means Frequency display with filter ;
"1" means RPM speed with filter;
"2" means Frequency display without filter ;
"3" means RPM speed without filter.
10 seconds later, the meter will automatically return to the measurement mode, or power-off and restart.
Divider/Multiplier Value Setup
NOTE: Disconnect the input signal before entering setup when the input signal is High level voltage signal (300V)
Open the back cover, press the "S1" button (left hand top corner) to enter the Sub-frequency Value Set interface,
"S1" button is the shift key which flashes the digit to be changed. Keep pressing till desired digit flashes.
"S2" button is the value plus key that increments the value of the flashing digit.
The divider value must be set to 1-99999 or the number of pulses per revolution
In the case of a distributor, one rotation of the distributor represents two rotations of the engine.
The divisor can be set to a value from 0.0001-9.9999. For a distributor a multiplier of 2 would be a divisor of 0.5000
Press "S1" until the decimil point of 0.0000 flashes. Pressing "S2" sets the decimal point. Then enter the appropriate
value as indicated before.
After the set of the desired divider value via "S1" and "S2", wait 10 seconds and the meter will automatically return
to the measurement mode.
Divider Concept:
The number of the pulses for one rotation. For example, a gear can make 20 pulses for one rotation , the divider value
should be set to 20.
High and Low voltage signal input switch
NOTE: Disconnect the input signal before setting when the input signal is High level voltage signal (300V)
The default set for this meter is the low voltage input (3-30V), if you need high-voltage input(30-300V), you need
to open the back cover and remore the black short jumer from the "L" pins (left bottom).
Failure to remove the jumper and input the high voltage directly will damage the meter if the low voltage short jumper
is not removed. We are not responsibility for this damage. Please be careful!!
Input Pins:
1: SIGNAL INPUT (YELLOW)
2: SINGNAL GND (BLUE)
3: NC
4: INPUT VOLTAGE "-" : GND (BLACK)
5: INPUT VOLTAGE "+" : VCC (RED)