High Frequency Fun
2009-09-11 09:08:00 It seems there is nothing that visitors to the Wireless Waffle web-site like better than a list of interesting radio frequencies to have a go at listening to. Previous articles in subjects such as frequencies for London airports, tuning into US military satellites and unusual UHF activity are some of the more popular pages according to the various logs kept by our web-server.So with that in mind, here are a few 'interesting' HF (short-wave) frequencies that might be worth a listen. Any frequency where recent activity that is most likely caused by the indicated source has been noted (either by Wireless Waffle or on other useful sources) is marked with an asterisk.Test and Development Frequencies2806, 5750, 7556, 9071, 10438, 11117, 16014, 18990, 20990, 24135 and 26218 kHzAccording to the 2007 UK frequency allocation table (Annex I) these frequencies are the preferred HF frequencies for test and development use (interestingly they have disappeared in the 2008 version. Anyo...
By: Wireless Waffle
Deflection at CG or Reed (Natural) frequency of motor
2009-09-09 12:25:00 how i can calculate Deflection at CG or Reed (Natural) frequency of motor. jagadeesha
what is the significance of all in "wind frequency distribution"
2009-09-05 08:59:00 Hello Friends I am new in the field of wind energy. Recently i encountered a wind frequency distribution chart. I could understand wind frequency distribution for specific direction but heading of last column, i.e. all has put me in a fix. Please help me to understand the significance and
Variable Frequency Drives and Generators
2009-07-28 13:35:00 Yair... me agin'. I'm wondering can a smaller generator with an out put (say) 20% higher than the name plate rating on the driven motor be used to start a variable frequency drive. That is to say... can the drive be gradualy bought up to speed from the lowest frequency setting thus obviatin
Variable Frequency Drive (VFD) and Plant Safety
2009-07-23 06:53:00 Dear all, we have VFD in the plant room where fan is operting for smoke exhaust system during fire in the building and this fan is used in normal as well as fire mode, now the question is will the VFD is safe when the fan runs in fire mode which reaches 250 deg c during this mode.
Line Resolution and Frequency
2009-07-09 07:33:00 Please help me regarding my quiries which are written bellow. 1. How I can set the line resolution of FFT screen?. The sample rate of in comming signal(Vibration) is 10k HZ. 2.The frequency specification of my accelarometer is 0.2 HZ to 6000HZ. Whwn I do the FFT of this vibration s
VARIABLE FREQUENCY MOTOR CHARACTERS.
2009-07-05 16:20:00 Dear CR4 FORUM MEMBERS, 1.What is the Specific Requirement for the MOTORS to be used for VARIABLE FREQUENCY DRIVE.? where the operational speed of the motor to be in the range of 700 R.P.M to 1200 R.P.M. 2.Is there any difference in the construction of conventional induction
Generator Frequency
2009-06-10 22:53:00 While the co-generator running in parallel with the utility grid, due to fault in the utility system, is the generator frequency is going higher or lower? What happens with the the reverse power relay, does it see higher or lower reverse power? The fault of the utility is within 5km of the generator
Single-Phase Power and Three-Phase Frequency Drive
2009-06-04 04:38:00 Will 240Vac single-phase power line drive a 3-phase freq drive with a 3-phase motor load connect to it? Don
Motors - Frequency of Lubrication
2009-05-19 22:39:00 How often should you lubricate a continuosly running motor.
Frequency Inverter is Over Current
2009-05-14 15:15:00 hi all , i have a 3 phase motor 14 Amp , operating a winch , i installed a frequency inverter of 23 Amp. to control the motor , i had a problem that when the motor started it spin 3,4 times then stop as the inverter gives the message " over current" however i defined the current li
Frequency Conditioning as applied to "free energy"
2009-05-12 18:33:00 Is the frequency of stretched materials (elastics,metals) too low to condition to use as grid style voltages?
frequency of a gas leak
2009-05-05 12:38:00 Can anyone give me the formula to calculate the frequency of the sound produced for a known pressure of gas leaking through a known size orifice
Frequency of Gas Leaks
2009-05-05 12:38:00 Can anyone give me the formula to calculate the frequency of the sound produced for a known pressure of gas leaking through a known size orifice
Grid frequency and Voltage in SA
2009-04-15 05:30:00 Dear, we are a small wind turbine manufacturer and exporter in China. One of our customers in South Africa met a problem in connecting our system(the inverter) into the local grid. The power voltage and frequency we set b4 shipment is 220V/50Hz which we searched online. Now we are concerning if
Pressure Transducer - Natural Frequency vs. Frequency Response
2009-04-07 19:55:00 When a maker shows only the natural frequency for a pressure transducer, what is the frequency response of the transducer if it is a strain gage based design? DC to the natural frequency or ?
power frequency withstand test
2009-03-29 16:41:00 dear u all.... can u give me a explanation about dry and wet power frequency flashover voltage and why the power frequency withstand test is important to any electrical equipments
Generator Load and Frequency
2009-03-23 15:13:00 Hello , for example i have a isolated synchronous generator and i turn off governor and AVR , i have some load(1 unit for example and a light one ) and i suddenly increase the load,so if all controls are off and i have an imbalance of load versus generation, so as far as i know the speed will decli
50Hz, work with 60Hz frequency
2009-03-20 22:03:00 conclusion that 50hz motor. ex.washing machine will work at 60hz (philippines) provided that it will also get burn from time of use.
Comparing High-Frequency Transformers
2009-03-19 12:39:00 What is the merits & demerits of bobbin type transformer over the toroidal transformer, for high frequency application & what kind of effects will be occured while interchanging these two transformers. Thanks in advance for your valuable reply.
Motor Frequency
2009-03-19 11:03:00 Motor rating is 380 - 400 V & 50 Hz, can we increase the frequency by using VVF drive up to 120 Hz? Please explain? my mail id: eswaran.subramanian@eu.effem.co-m s_eswaran2000@yahoo.com Many thanks, Regards,Eswaran
Variable frequency drive for high speed spindle
2009-03-19 06:09:00 I operate a CNC router table with a high speed spindle. I'm looking to upgrade to a new spindle but need to know if the variable frequency drive I currently have will work with this new spindle. The new spindle has the following stats: 300Hz, 1kw, 18000RPM. The frequency drive is made by LS
Variable Frequency Drive (VFD) for High-Speed Spindle
2009-03-19 06:09:00 I operate a CNC router table with a high speed spindle. I'm looking to upgrade to a new spindle but need to know if the variable frequency drive I currently have will work with this new spindle. The new spindle has the following stats: 300Hz, 1kw, 18000RPM. The frequency drive i
SIL reduction by Increasing the testing frequency
2009-03-04 11:13:00 we all know that one of the method to mitigate harm and reduce risk is increasing the testing frequency of critical components this understood very but the how this affect the SIL of the SIS ? Is that becouse increasing the frequency of test will decrease the the dangrous undetect fault wh
Running AC Motors Over Frequency with VFDs
2009-02-26 06:27:00 OK, I've got my fireproof underwear on for this one. I am currently deep into the planning stages of an Electric Vehicle powered by a 3 Phase AC motor. The motor has become more complex than first thought. I'll set out some basic requirements first. 1. 1 want to use
Do Frequency Drives Save Power?
2009-02-25 08:47:00 Dear all, We have an electrical motor of 3.0 HP ( rpm 1440 ). We are going to install frequency drive to set it's rpm at low ( less than 1440, it may be 400, 700 etc ). I want to know that does frequency drive saves power while motor is same ( 3.0 HP ) only rpm is reducing ? If yes, then pl
Variable Frequency Drive (VFD)
2009-02-23 11:20:00 How to build and design a VFD the application is to drive motor and controll the speed refering to the load with spped feedback signal only. no need for other options
Variable Frequency Drive (VFD) and Motor Operation
2009-02-17 00:11:00 Hello friends, We have one PLC controlled SPM having one motor controlled with VFD for table rotation at required speed. Now we are facing problem that; in night shift there is abnormal operation of this motor( Rotates when not required). During a period of 06.00 to 01.00 problem doesn
Motor Frequency
2009-02-14 11:09:00 Off late we are getting too many threads what happens if we have a supply of 50Hz, 230 V and the requirement is 240V, 60 Hz and vice versa.Should we CR4 members have a discussion (along with guest artists) and form a permanent link and then we can refer it to others instead of repeating them again
Frequency Converters
2009-02-13 17:14:00 Hello Gentleman I am looking for information on what type of frequency converter to use to change the frequency from 230V 50Hz to 230V 60Hz. The required power supply is 230V 60Hz single phase. I have both 230V 50Hz single phase and three phase power supply. I also understand that the comp
Phase-Locked Loop(PLL) Frequency Synthesizer
2009-02-07 11:21:00 I am doing a project which requires us to design a PLL frequency syhthesizer with the following specifications: Frequency range: up to 10 MHz or better Output voltage range: 0 to 5 V I am planning to use 74HC4046 IC can teach me how to design the circuit for this frequency synthe
High Frequency Mixers and Ultrasonic Amplifiers
2009-01-28 04:00:00 any one can send me circuit diagrams of 1. a high frequency mixer 2. and an ultra sonic amplifier i am doing a project on "ultra sound " and if get the circuit diagrams, it ll be a great help for me.. my e mail id is pramodspark@yahoo.com
Digital Communications and Frequency Hopping
2009-01-21 19:13:00 My company repairs wireless communications and is learning digital coomunications and frequency hopping. Can anyone tell me what we equipment we would need to see the frequency hopping sequence. Also do you know of any online schools we can learn troubleshooting for digital systems.
How to Choose Cut-off Frequency
2009-01-19 17:42:00 In biomechnaics, we usually have to filter our raw dada from human movement etc.. Are there any theoretical background or method how we choose filtering parameter, especially cut-off frequency ? Advice or comment, pls..
Rubidium Frequency Standard
2009-01-10 21:00:00 I have been told that rubidium frequency standards are hard to maintain. Is it true of the type shown here? http://cgi.ebay.com/ws/eBayISAP-I.dll?ViewItem&ssPa-geName=STRK:MEWAX:IT&it-em=290286908728 These show a better stability than the other 10MHz oscillators in ebay at this ti
Reduce pulse frequency for rev counter
2009-01-04 14:44:00 Hi, My friend has just replaced the engine in his car. The old engine was a 4 cylinder, and the new one is 6 cylinder. His Rev counter recieves a pulse from each cylinder, during its rotation. I'm looking for a frequency mulitplier circuit that would take a variable frequency input, and
soft stater (Static frequency converter)
2008-12-19 07:17:00 what is sfc, and how it's operation can you explain in detail working principal, function, application's please explain in detail yogi
Playing with Python - nmap XML port frequency
2008-12-16 09:27:00 Two Python libraries have caught my attention lately, the first is lxml and the second is matplotlib. Ideally I wanted to write something short, just to get a feel for the basics of them. The goal was figuring out what I could do quickly so that I could play around with arguments and output, yet ...
By: ComputerDefense
Natural Frequency of Vertical Pressure Vessels
2008-12-12 07:41:00 How to calculate the natural frequency of vertical pressure vessel.? Please send me link if it exsists related to my question.
nirs vs rf (near inrfared ) vs (radio frequency )
2008-12-09 20:44:00 nir spectrometer vs radio frequency moisture sensor applycation on food solids any help prices of sensors
relation b/w active power and frequency
2008-12-06 10:42:00 Low frequency indicates too little generation relative to load..Can u give the explaination for this statement? How the variation in active power generation affects the frequency in the power system for a particular load...??
Higher Frequency range
2008-12-04 13:57:00 While we are using the high frequency ranges , we are facing more signal losses as well as more distortion. Please explain.
Higher Frequency Ranges, Signal Losses and Distortion
2008-12-04 13:57:00 While we are using the high frequency ranges , we are facing more signal losses as well as more distortion. Please explain.
software for Radio Frequency(RF)
2008-12-04 08:28:00 Is their any software avaliable for Radio Frequency(RF) module simulation.
High frequency range
2008-12-03 13:41:00 While we are select the higher frequency ranges , we are facing more distortion as well as more attuanation(losses) Please explain.
Relation between frequency, penetration and coverage
2008-11-09 11:16:00 I am confused as how frequency, penetration and coverage distanace are related. I hear people saying signals with lower frequency can cover a greater distance than higher frequencies and also these signals have higher penetration capacity(pass through objects) becuase they have a greater wavelength.
X-Ray Wavelength and Frequency
2008-10-31 21:00:00 Here's the question: If one has an X-ray device that fires an n Volt pulse into the X-ray tube, is there a general rule of thumb to guesstimate the energy of the X-rays produced by the tube? I want to determine the energy of the resulting X-rays in order to calculate their wavelength. So, i
high frequency integrator
2008-10-28 00:45:00 Hi, I am looking at integrating a high frequnecy changing current (di/dt) between 30MHz and 200MHz which is the output from a current transducer. From what i can tell that at this high a frequency useng an opamp would make this difficult to achieve. Are there high frewuency opamps which could b
Frequency Modulator to Adjust GPM of a 5HP 230v Fountain Pump in NYC
2008-10-14 06:38:00 hi, we would like to know which method is best for controlling the GPM flow from a 5HP 230v fountain pump. We have been advised by two different experts. --one claims use a frequency modulator the other just dampen flow with a valve. (which could place more load in the pump??) the reason for this is |
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