Conceptually it is straightforward to predict the radiofrequency (RF) exposure intensity at any point in the vicinity of a cellular radio base station antenna. Simply multiply the effective radiation power times the inverse square of the distance times the relative gain of the antenna in the direction of the interest. The relative gain in different directions is know as the antenna radiation pattern and is usually available from the antenna manufacturer in graphical or tabular form.

Unfortunately, in real life the calculations involved in base station antenna evaluations are quite complex and require expert knowledge and experience to deal with the many parameters that are involved. An excellent reference summarizing this process is the Federal Communications Commission OET Bulletin No. 65 titled "Evaluating Compliance With FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields," available on the Federal Communications Commission (FCC) website.

To assess the RF hazards associated with handheld cell phones it is necessary to predict the rate of absorption in the body of radiofrequency energy, a parameter called the specific absorption rate (SAR). This is a very complex calculation, and cell phone manufacturers often rely on measurements of SAR in fluid-filled cylinders or plastic containers in the shape of a head. The FCC requires cell phone manufacturers to provide this data to FCC. You can obtain the data for your model phone on the the FCC's website. Unfortunately only cell phones manufactured in the last couple years are listed here.

As to your question about keeping RF exposures within the safety code, please read the other questions posted on this website this matter. Cellular radio products that meet FCC requirements will be within the guidelines established by safety standards organizations for users' and public exposure to RF radiation fields.

Gary H. Zeman, ScD, CHP

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FIRST OF ALL, THANKS FOR DESIGNING A WONDERFUL SITE. MY QUESTION IS: HOW DO YOU CALCULATE EME (ELECTROMAGNETIC EMISSIONS) AROUND THE TRANSMITTER (ANTENNA) AT ANY GIVEN POINT AND WHAT ARE MEASURES TO KEEP IT UNDER SAFETY CODE?

The leadscrew length for the greenBull long Z-axis is 47 inches.

Additional Information:

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BUILDING ONE OF YOUR GREENBULL 6X LONG AND 2.2 KILOWATT SPINDLE DOES NOT FIT. SEEMS LEAD SCREW YOU SENT WITH KIT IS SHORT 42" LOOKS LIKE IT NEEDS TO BE 5 OR 6 INCH LONGER. THIS CORRECT? WHAT THE NEEDED LENGTH FOR UNIT?

Can you send me a link to the digitizer you are using?

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Hi my names is Minh Truong I would like to said thank you very much for your video I got the system mach3 working fine but one thing I can NOT set and config the digitizer on the board IN4 I am not sure how to setup because in the Mach3 pin 14 for digitizer Please shoe me hoe to set it up for the digitizer.

See the question on our "Ask the Expert" question-and-answer list on cellular towers under nonionizing radiation for a discussion of RF safety issues associated with cellular radios. The technology underlying cellular radios and base station antennas is similar around the world, but there are differences in systems design and RF safety limits in different countries. For a summary of cellular radio RF safety issues with attention to international differences see the excellent Web page, Cellular Phone Antennas (Base Stations) and Human Health, by John E. Molder, Ph.D., from the Medical College of Wisconsin. Gary H. Zeman Sc.D., CHP

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I LIVE IN ITALY AND WISH TO KNOW MORE ABOUT RADIATIONS CAUSED FROM MOBILE TELEPHONES. TELECOM WOULD LIKE PLACE A WIRE-ANTENNA THE HEARTH OF MY TOWN, I'M AFRAID IT. WHICH KIND RISK HEALTH COULD IT CAUSE? THANK YOU IF WILL SEND ME SOME INFORMATION SCIENTIFIC ARTICLES THIS PROBLEM!

The files and hardware option for our machines has been removed from the site due to the following reasons:
Difficulty for the end use of the files and the challenges (and time/money) on our side to assist in using these files.
The abuse of these files over the internet.
Ultimately may reduce the sales of machines keeping us in business.
Sadly, this is what has come out of our company attempting to be open; however, the machines sold on this site is still far lower in price than the competition for the quality that we provide as we have a great desire to engender the cottage industry to fulfill their need for low end manufacturing. My sincere apologies if this causes any inconvenience.

Additional Information:
NO, is not possible, I can help with the shipping cost

Additional Information:

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IT POSSIBLE TO BUY THE CAD FILES FOR BLACK FOOT MACHINE, MECHANICAL PARTS AND ELECTRONICS BUT NOT WOODEN PARTS, SAVE SHIPPING COSTS? IN THAT CASE I WOULD INSTRUCT SOMEONE MILL ME.

We have a local pickup option $0.00. The shopping cart will provide the usual USPS, FedEX and UPS. A machine will generally require three packages and the shopping cart will consider this in the request for rates from USPS (multiple shipments), and FedEX.UPS (multiple package single shipment). The rates are based on the package dimension and weights and the rates for these dimensions returned from the carrier.

If you enter your shipping address in the shopping cart and press the calculate shipping button, you will get a list of these rates.

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WE HAVE A LOCAL PICKUP OPTION $0.00. THE SHOPPING CART WILL PROVIDE USUAL USPS, FEDEX AND UPS. MACHINE GENERALLY REQUIRE THREE PACKAGES CONSIDER THIS IN REQUEST FOR RATES FROM USPS (MULTIPLE SHIPMENTS), FEDEX.UPS PACKAGE SINGLE SHIPMENT). ARE BASED ON DIMENSION WEIGHTS THESE DIMENSIONS RETURNED CARRIER.

BYCNC Response:
This is correct. You will need to use a method appropriate for the software you are using. Also remember that NC switches are typically wired in series, while NO switches are normally wired in parallel.

User Response:
I am using the cnc planet software for your USB board. Are the limit configurations in this software?

BYCNC Response:
Yes, Planet CNC software is compatible with the use of limit switches. Configuration information will depend on your specific application. You can view Planet CNC's information here: http://www.planet-cnc.com/files/CNCUSBController.pdf

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LIMIT SWITCHES FOR AXIS. THE PRINT SHOWS THAT YOU CAN WIRE LIMITS EITHER N.O. OR N.C. SO IF THIS IS CORRECT I WOULD NEED TO TELL BOARD IN SOFTWARE HOW LOOK AT THESE LIMITS, I'M GOING GET AN INPUT LOOSE DEPEND ON IT.

When the z axis is going down, the laser turns on. When the z axis is going up, it turns off. The z axis directions is only a signal that is either 5v or 0v. That determines the direction. In vectric, you will need to set your machining operations with a very very small depth so the time it takes to get to its final depth is a very short time.

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AM NOT SURE HOW TO SET THE Z AXIS TURN ON/OFF LASER WHEN CREATE CODE. KNOW THAT ITS TYPICALLY Z-AXIS MOVEMENT DOES THIS - BUT YOU DONT SHOW ANYTHING HOOKED UP IN PLACE OF AXIS.

Yes, the blueChick kits are available. You can get the shipping rates automatically in the shopping cart. There will be a calculate shipping button on the enter shipping information section of the shopping cart.

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CAN YOU PLEASE TELL ME THE AVAILABILITY OF 12X36 BLUE CHICK 4.2, AND COST FOR SHIPPING TO ZIP 72802 IN RUSSELLVILLE, ARKANSAS?

Can you provide the model number of your VFD?

Yes, I have the "YL600 - 2S - 2K20"

It just came with a small booklet that is all in Chinese...

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I WIRED MY VFD (2.2KW VERSION) AND TRIED TEST RUNNING THE SPINDLE. CONFIGURED TO YOUR SPECS ON THIS WEBSITE, ONLY ISSUE IS WE GOT AN ERROR CODE. ERR 02, DO YOU KNOW WHAT IS? OR HAVE A LIST OF CODES? THANK

You can actually set a current limit in in the VFD using the programming process and the specifications in the manual that came with your VFD. You can expect the spindle at 220 Volts AC to draw (using the standard formula):

For Volts, I will use 230 as the range is generally 220 to 240.

Watts = Current * Volts

Can also be written as:

Current = Watts / Volts

Current = 2.2kW (2200 watts) / 230 volts

Current = 9.6 amps

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I have the 2.2 kW spindle and VFD for 110v, just wondering what amperage this draws, as my electricain buddy is telling me I need to put in a 20 amp breaker for this. I cant seem to find any amerpage draw on the INPUT label

Your steps per inch will vary. I suggest watching my calibration video.

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I AM CURRENTLY HAVING SOME PROBLEM SQUARING THE GANTRY AND MY STEPS PER INCH ARE NOT 1422.22 ACCORDING TO YOUR CALCULATIONS IN AUTO SET UP THEY COME OUT LIKE 1416.#### THIS A BIG DEAL?

The CNC router build from book "Build Your Own CNC Machine" uses the basic electronics combo kit that includes three 425 oz-in motors is the kit designed for that machine. Here is a link to that electronics package: https://www.buildyourcnc.com/Item/electronicsAndMotors-3axis-425-elcombo

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I AM BUILDING THE CNC DEMONSTRATED IN YOUR PUBLISHED BOOK 'BUILD OWN MACHINE', 2009. YOU SELL 3 AXIS ELECTRONIS COMBO, PARALLEL, FOR $390. IS THIS PACKAGE FROM BOOK. OR ARE THERE OTHER RECOMMENDATIONS. THANK YOU, HARY HOLSTEIN

You will need to look for the parameter that controls the run frequency. The frequency can be controlled bu the panel, external terminals, or the RS485 TX/RX terminals (UART protocol). You will want to change that parameter so it uses the panel. If you are referring to the maximum panel dial frequency is only allowing 200-300 rpm, then look for the parameters to control the frequency.

For 200 RPM:
Hz = 200/60 = 3.33 Hz

For 300 RPM:
Hz = 300/60 = 5 Hz

Conversion to RPM:
If you ever find yourself yearning to reverse-engineer the process, the formula is as follows:

RPM = Hz × 60

Look for values that match somewhere between 3 and 5 in your frequency parameters and replace them with 400 to give you 24,000 RPM max.

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I HAVE A 2.2KW WATER COOLED SPINDLE WITH YL620-H VFD. THE VFD USES P#-## PROGRAM FORMAT. BELIEVE ALL CORRECT SETTINGS SETUP BUT WHEN TURN UNIT ON, IT SPINS AT ABOUT 200-300 RPM REGARDLESS OF WHAT FREQUENCY CHOOSE. DO YOU PARAMETERS IN THIS FORMAT FOR UNIT? THANK YOUR HELP. HUIBERT MEES

Is the signal gnd on the laser power supply connected to a gnd on the breakout board? Do you hear a high pitched sound, like a TV set with an antenna getting interference, but with a high pitch?

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OUR FIRST ATTEMPTS WERE WITH THE PLANET-CNC SOFTWARE, GOING THROUGH USB BOB. NO PROBLEM GETTING X & Y AXIS TO MOVE BUT UNABLE GET ANY ACTIVITY ON Z AXIS. WE THEN INSTALLED MANUAL SWITCH BETWEEN 5V AND TL, JOY. DISCONNECTED BOB FROM TH, MOVED OVER TH TL STILL

BYCNC Response:
Please send a photo of the bolts and assembly so we can determine the problem. Thanks.

User Response:
The holes on the Dremel holder are 0.442" and the bolt heads are 0.483". Picture will be sent. In the picture note that the left bolt has been ground down.

BYCNC Response:
You were sent incorrect fasteners due to a vendor change. We will be shipping the correct parts to you immediately, and thank you for letting us know about this mistake.

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I JUST RECEIVED MY WHITE ANT AND STARTED TO DO SOME BASIC ASSEMBLY. NOTICE THAT THE 1/4 X 20 BOLTS WITH PHILLIPS HEAD NOT FIT IN NOTCHES CUT FOR THEM - INSTANCE, ON DREMEL MOUNT. AM SUPPOSED BUY DIFFERENT HEADS, GRIND ALL DOWN, OR ROUTE OUT BIGGER NOTCHES. 3" BARELY Z-AXIS MOTOR

There has been a cell phone base installed in the fire tower. The panels are vertical and located about 75 feet at the top of the tower. Unlike some towers I have seen there are no round disks and no beaming lights. At night, the tower and cell phone material are dark. Does this make any difference in any related health issues with RF exposure and is it possible the tower is a receive-only transmitter ?

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THERE HAS BEEN A CELL PHONE BASE INSTALLED IN THE FIRE TOWER. PANELS ARE VERTICAL AND LOCATED ABOUT 75 FEET AT TOP OF UNLIKE SOME TOWERS I HAVE SEEN NO ROUND DISKS BEAMING LIGHTS. NIGHT, TOWER MATERIAL DARK. DOES THIS MAKE ANY DIFFERENCE RELATED HEALTH ISSUES WITH RF EXPOSURE IT POSSIBLE RECEIVE-ONLY TRANSMITTER ?

Pulsed radiation fields are encountered in the vicinity of electron Linacs (McCall and Ipe 1988). Most therapy Linacs are operated at repetition rates varying from 100 to 400 pulses per second with pulse widths of about 1 to 10 microseconds (AAPM 1986). The fraction of operating time (that is, pulse width x repetition rate) during which the beam is on is called the duty factor. For example, the duty factor for an electron Linac operating at 100 pulses per second with a pulse width of 10 µs is 0.001. These small duty factors impose severe limitations on the radiation detection instruments. The peak intensity is equal to the average intensity divided by the duty factor, which in this case will be 1,000 times higher than the average intensity. An instrument that normally responds well to the average dose rate spread out evenly in time will not be able to cope with such a high dose rate. The intense photon pulse usually overwhelms any active detector (that detects particle events electronically). Instruments which have long dead times, such as the GM and proportional counters, tend to become saturated in such fields and only count the repetition rate. Thus GM counters should not be used to perform radiation surveys outside exterior walls of the Linac room. Scintillation survey meters may become nonlinear at higher dose rates because photomultipliers cannot handle the high instantaneous currents.Ionization chambers are less influenced; however they must be operated with adequate voltage to overcome recombination losses. There are several commercially available ionization chambers that can be used for Linac radiation surveys

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THE ROOM HAS THICK CONCRETE WALLS PLUS LEAD SHEETS. LEVELS OF EXPOSURE I AM GETTING WITH LUDLUM MODEL 3 SURVEY METER (SM) A 44-9 PROBE ARE BETWEEN 0.1-3 MR/H IN WORST CASE (HIGHER ENERGY AND POINTING BEAM TO WALL). SM WAS CALIBRATED 137CS MY NOMINAL 18 MV (MEAN ~5 MV). WHAT KIND INSTRUMENT MORE ADEQUATE USE FOR THIS TYPE BETTER RESPONSE?

Here is the answer to your first questions regarding the blueChick motors:
https://buildyourcnc.com/FAQ/9024

The shipping of the blueChick CNC will depend on if the machine is assembled or not. There is a duty for international orders, but I am unsure of the cost in other countries other than the US.

Thanks

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What are the specs for the stepper motors on the Bluechick? How much for shipping to Toronto, ON, Canada? Is there duty for shipping to Canada?