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  1. betkro

    CFL Inverter transformer insulation problem

    I have an inverter project for emergency lighting with two 110W CFLs. The circuit uses bipolar transistors powered from 12VDC in a self-oscillating push-pull topology. Both lamps must be insulated from each other, which requires to have isolated secondary windings. Lamps are connected through...
  2. betkro

    PCB design - Orcad or Protel

    You didn’t mentioned your budget. I use OrCad, also EdWin that’s very powerful for just 150 bucks!.
  3. betkro

    Switching power supplies

    SMPSs deserve special consideration in circuit engineering. They require a deep knowledge of electromagnetism besides electronic circuits and components. Magnetic materials and inductor and transformers manufacturing and testing is essential when you design an SMPS for commercial purposes. I...
  4. betkro

    communication

    Yeah!. let's go back to the germanium era.
  5. betkro

    gps & Rfid interface

    I faced a similar problem some years ago regarding the distribution fleet of a bottler company. Three main, and independent, issues were considered: Security outside the facilities (“road navigation”), access control and displacement inside the facilities. In that case, the operating...
  6. betkro

    gps & Rfid interface

    Good point VE1BLL, still, my question remains.
  7. betkro

    Help with a timer circuit...

    BKSwindell, There are some errors in your schematic. The '555 is not intended to work with a floating ground (pin 1) as seen in the schematic. This is tricky and its behavior can be unexpected. The pin 2 is permanently grounded making R6k8 useless. Why the use of a SCR? . Once triggered, there...
  8. betkro

    gps & Rfid interface

    gstq54, let me know if I understood correctly the problem. You have two id systems: One RFID (buried loop antennas I assume, i.e., the tag readers) and a GPS, which you want to combine. The vehicles move among several sites. Do the rfid tags come from an access control system? . Are the location...
  9. betkro

    kalman filter text

    Hi, 2dye4. Do you have a specific application in mind, all-pass, SSB, VSB, digital or analog data filtering, etc.?
  10. betkro

    Was Nyquist right?

    As communication engineers, we are accustomed to dealing with signal processing as a “signal recovery" process. Data transmission and audio/video compression are common examples of sampling and modulation methods primary oriented to error-free demodulation and efficient use of the frequency...
  11. betkro

    Z80 Microprocessor w/ Floppy drive

    In my opinion and experience, software does not help to learn computers. Electronics does.
  12. betkro

    T-Type flip flop from NAND gates

    To be more precisely, the base is a master-slave FF. This is accomplished from two S-R FFs (two NANDs) and associated logic. Then, connect Q output to K (inverting) input and /Q (inverted output) to J (non-inverting input). A T type FF is also a one stage divide-by-2 register. try...
  13. betkro

    Crystals vs. Ceramic Resonators

    Certainly, your issue is mass production. Try also the Microchip Community Forums and manufacturers’ advice regarding parallel oscillators at that frequency range.
  14. betkro

    Crystals vs. Ceramic Resonators

    In my experience with PICs, there is no difference in using both oscillator alternatives. I’m currently driving a design with RC, ceramic and crystal oscillators, at 4MHz (RC and XTAL resonator) and 16 MHz (XTAL + caps). An important issue is the start up conditions -I mean power supply’s rise...
  15. betkro

    protect 3 ph motor from loss of 1 phase

    buzzp's comment “_before they start_” is exactly that of a friend of mine, asking to advice him in the matter herein. That's right. A voltage measuring relay cannot DETECT phase loss because of voltage regeneration at the lost phase terminal. However, a [good] undervoltage relay can PROTECT...
  16. betkro

    protect 3 ph motor from loss of 1 phase

    pumpdesigner, Transients... Good point. Effectively, the isolation, surge withstand capability, ambient protection, also sturdiness, among others, is essential in static relays. In general, certifications and test results are presented in relay’s data sheets by the mfg. However, harmonic...
  17. betkro

    protect 3 ph motor from loss of 1 phase

    This is just to show the test results made on a small 220/380V 3HP general purpose motor. Releasing a phase, the free leg voltage imbalance went to 2.7% and no anomalous behavior was noted (as expected.)Then, by burdening a little the rotor axis, the imbalance rapidly went to 4.5%. A simple...
  18. betkro

    4-20 mA loop sheilding

    All this sounds as pink noise.
  19. betkro

    FFT with and without a low pass filtering

    es335, Let me see if I had well understood your question. By frequency measuring, I assume you mean “sampling”, because you associate to the Nyquist criterion. Certainly, you are not obliged to obey this criterion to make a frequency measurement, just to faithfully recovering the waveform or...
  20. betkro

    4-20 mA loop sheilding

    Mgopalan, I think that you have a communications problem rather than a grounding problem. Try using industrial grade instrumentation cable from Belden or similar. Don’t forget to terminate both sides of the line with the same EOL resistor, matching the characteristic impedance of the cable...

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