Topic: Connecting an R M Young 05103 Wind Monitor to a Davis System

[wxtech]

I designed and built several wind converters that allows an R M Young 05103 (or similar) wind monitor to operate with a Davis VP2 ISS.  I have 2 devices operating successfully.  I will share my design and offer a circuit board for purchase if anyone else wishes to build the interface.
Don't rush out and buy that RM Young just yet.  My circuit still has a fault.  It works but just not with the 3 volts power source that I intend.  It's a simple interface.  Perhaps someone will wish to design and build their own RMY - Davis converter.

I'll publish here the wind monitor specifications, conversion factors, and waveshapes.  Later, I'll add a suggested circuit and printed circuit board pattern.

[wxtech]

Warning:  If you purchase a used wind bird from Ebay or surplus source, you may get a defective wind monitor.  I purchased one that apparently had been struck by lightning.  The generator output was erratic and noisy.  Also it was missing some parts.

[safuser]

Did you ever get anywhere with this?  Looking to do something similar with a RM young 05103 as well.

[wxtech]

I have converted several various models of RMY to use with the Davis VP2+ weather stations.  When ordering a used RMY, get a return warranty and test what you receive. 
Wind direction requires no modification.  Davis uses a 20K pot, RMY uses a 10K pot.  The smaller resistance doesn't matter.  Just straight wire the direction leads.
Wind speed requires changing the RMY AC generator output to a square wave and divided by 10.  Just square the RMY speed signal with op-amps and use a  CD 4018 divide by 10.  A transistor output stage drives the cable to the Davis wx station.
RMY uses a special magnet on the impeller shaft that has 6 poles.  This produces 3 sine waves per revolution.  We don't care about the amplitude, just the frequency. 
Give me time to locate a schematic and board pattern.
Good luck

[safuser]

Awesome. Thanks!  Can't wait to see the schematic.  Exactly what I was looking to do. Just wasn't sure on the components and had not come across anyone who had done it successfully.  Much appreciate the assistance!

[wxtech]

The attached image is from 10 March 2012 showing variations of the RMY/Davis VP1/VP2 converter board.  I'll dig out the parts today and try to find the schematic and board design.

[safuser]

Interesting.. What I have been looking at is using a H11AA1 to convert from the Young Sine wave to a square wave(Basically as a zero-crossing detector).  I guess you are doing something similar then using the CD4018 to divide the count down to what the Davis Board is expecting? Not sure if the H11AA1 is the right chip to use?  I was wandering about the voltage the young produces? From the spec the voltage on the young anemometer varies with speed? I was wondering if the voltage is enough to trigger the H11AA1 at low speeds?  Also not sure what value to use on resistors on input to H11AA1?

[wxtech]

I'll put an RMY wind monitor on the bench mounted in the Climatronics Calibrator (image attached).  It has a motor to drive the speed shaft at selectable speeds.  I'll measure the voltage output at low speed. 
I have some H11A1 simple optoisolator parts and will what the pulses out look like.

[wxtech]

I put an RMY 05103 on my workbench connected to a calibrator.  I'm turning the speed shaft at various speeds.
The H11A1 has a single led for DC input while the H11AA1 has dual leds for AC input.  I didn't connect an optoisolator to the RMY 05103.   
I haven't converted to MPH but at 3 wind (shaft) speeds, the generator output is #1 336mv @ 10HZ, #2 600mv @ 21HZ; and #3 highest speed 2.28 volts @ 86HZ.  The generator produces three cycles per revolution (1RPM=3HZ)(1MPH=0.01096RPM)
This means that at very low wind speeds, the generator doesn't produce an output voltage high enough to drive the H11AA1 leds.  Using an optoisolator, the wind measured threshold will be several MPH (no output) even with the impeller rotating.
I believe that I'll have to stick with my design using op-amps to amplify and square up the generator output.  I'll get back to that old circuit soon.

[safuser]

Rgr.  I was afraid of that.  Sounds like your design is the way to go with op-amps to boost the input signal.  Look forward to seeing your schematics and parts list.  Thanks!

[safuser]

Finally picked up a RMY anemometer from EBay at a reasonable price.  Unfortunately it was not the model I expected with the standard interface.  Found out it was the 05103-11 with Pulse Squaring Circuit. 20+ years old. Put it on the scope and it produces a nice square wave at 3 per revolution.  Have attached schematic. Was wondering if this circuit is similar to yours.  Might ditch the built in circuit as it looks like it needs >=4.5v for the ICL7662 to function properly.  I'd really like to feed it 3.3v, so was looking at using a LM393 zero crossing detector(Fig. since the 393 looks like it will accept 3.3v.

[wxtech]

I don't know about the -11 version.  It looks like the ideal to interface to the VP2.  All you need is a 4018 divide by 10 stage inserted between U1 pin 7 and R6.  Hook R7 to +3 volts.
Keep Q1 where it is to drive the output cable.
I've had too many obligations to work on this project lately.

[wxtech]

I haven't had hands on a Davis or RMY project for ages, so I'm guessing now.  You may be able to 'steal' 3 volts from the Davis SIM.  Try  connecting the Q1/R7 to the black wire coming from the Davis.  This wire is pulled up to +3v in the Davis SIM.  If the RMY to Davis cable doesn't need too much drive.  Davis keeps +3v on this wire until the reed switch grounds it.
Check that the LM393 will respond to a wind speed signal of 336mv which is 10Hz.

[wbkkwx]

Hi wxtech,

with the davis 6336 universal anemometer interface for Davis now discontinued, do you have plans to produce the board if it is working well? thanks.