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  1. waveboy

    Comparator input bias current in STM32L073 micro?

    Hi, Do you believe that the attached LTspice simulation is the best way to analyse the effects of the input bias current in one of the comparators inside the STM32L073 (48 pin) microcontroller? STM32L073 datasheet https://www.st.com/en/microcontrollers-microprocessors/stm32l073rz.html I...
  2. waveboy

    Why not have a combined LISN/Spectrum analyser for conducted EMC?

    Hi, This concerns conducted EMC testing for offline SMPS They use a spectrum analyser and a LISN. The spectrum analyser can be irepairably damaged by.. 1....the detector in the Spec Anal getting overloaded by the input from the LISN 2...The RF input of the SPec An getting overpowered...
  3. waveboy

    Burst Mode SMPS wont fail EMC

    Hi..........its amazing how a massive number of Power electronics company staff think that a burst mode SMPS is worse at EMC , than a standard frequency compensated SMPS.....which if course, is totally not true....neither does it fail flicker. I once worked at a co, where they had a 600W UV...
  4. waveboy

    Difference between HV and LV output LLC converter?

    From what i see, there is essentially no difference in an LLC for 15kv, 2kw output, and an LLC for 2kw, 200V output. ...other than the obvious different turns ratio....and the need for special HV isolation material and clearance. Also the fact that you are forced to do an "Integrated...
  5. waveboy

    SMPS feedback compensation error amplifier with finite gain at DC?

    Hi, You have type 1, 2 & 3 error amps for SMPS feedback compensation... But what is the error amp called that is just a high gain inverting amp?...ie, not an integrating error amp. Also, can you confirm, that using this (unknown name) error amplifer, there is no gaurantee in eg a Buck battery...
  6. waveboy

    Power consumption of fan at increased voltage

    Hi, Do you know what the power consumption of the 624HH Papst fan is at voltages from 18-30V? 624HH fan https://img.ebmpapst.com/products/datasheets/DC-axial-fan-624HH-ENU.pdf?_ga=2.173156963.1761286910.1643461652-146278518.1643461652 Its rated 18-28V, but we intend to run it mainly at 30V...
  7. waveboy

    How to design a single phase , 50Hz, 240VAC inverter (grid tied)

    Hi, Would you agree, that this is a simple job? One simply has to set up sinusoidal PWM into a H bridge, and have output current limitation. You make sure your DC bus is say , 400V, so that its always above mains peak...then you simply sinusoidally PWM it.....the sinusoidal PWM is made by a ref...
  8. waveboy

    Fluxgate current sensor without equal core saturation in both directions?

    Hi, What if the schem on fig3, page 3 (of the below) is done without the compensation error amplifier , U2? Fluxgate current sensor: http://www.cpdee.ufmg.br/~troliveira/docs/papers/Induscon_2018.pdf This article was sent to us by our Chinese associates, who are offering us ferrite...
  9. waveboy

    What offline equipment needs >6mA DC leakage current detection?

    Hi, What mains connected equipment needs a >6mA DC leakage current detector? (and why?) This article says equipment needs it if it's mains connected and contains a "DC powered battery" https://www.electropages.com/2021/03/new-leakage-current-sensor-electric-vehicle-charging-stations
  10. waveboy

    Make RCD for 32Arms mains distribution box

    Hi, We wish to make an RCD to detect 30mA of imbalance current between line and neutral, and also detect 6mA (and more) of DC leakage current. We wish to use a fluxgate current sensor, but we believe it can be done without using feedback, and with just a single "non-square" torroid core (ie a...
  11. waveboy

    Radiated EMC test with chassis earthed or chassis floating?

    Supposing we take the following set-up to a Radiated EMC test chamber (30MHz – 1GHz)… We have a 12V battery in a totally enclosed metal enclosure X. A cable from this battery leaves this enclosure and feeds into another metal enclosure, Y, which is semi open, since its front panel is...
  12. waveboy

    EMC filtering for real situations?....not the usual ideal setup

    Hi, We have got to pass radiated EMC (30MHz to 1GHz), but in a “real” situation where we cannot afford “proper” RF EMC techniques…and in truth…”real” EMC techniques just wouldn’t be mandated, or realistic. Our setup is as attached. The following doc calls for a “RF Reference plane” for use...
  13. waveboy

    Offline flyback SMPS transformer has "gappy" shield windings

    Hi, Just doing an Offline Flyback transformer for 13.7V and 3A output. VAC input is 240VAC. We are doing it sandwiched [Pri1 – Bias - Shield1 – SEC – Shield2 -Pri2] I found it impossible to wind the shield without “gaps” (as attached) between the coils, due to the uneven winding surface. (due to...
  14. waveboy

    Near field antenna to tell if radiated emissions are better or worse after modification to circuit?

    Hi, We have an SMPS in an earthed metal enclosure A, which is wired to another SMPS (12W) in another earthed enclosure B. B contains 4 SMPS chargers of 3W each. A is totally enclosed, with only a few holes of dimension much smaller than the wavelength of the problem frequencies of 50MHz to...
  15. waveboy

    Battery pack for robot

    Hi, We intend to use a 6S/6P AA LiPO cell array for our robot. Is it best to have a block of 6 cells in parallel, and then put 6 of these in series? Or is it best to have 6 series strings...and then put these 6 in parallel?
  16. waveboy

    Air temperature inside totally enclosed plastic box with resistor dissipating 6W inside it?

    Hi, Supposing you have a totally sealed hollow plastic rectanguloid box. Dimensions are 150mm by 60mm by 40mm Wall thickness is 1mm Plastic thermal conductivity is 0.2 There are extremely thin electrical wires going into the box. These wires supply 6W of power to a small resistor (Resistor dims...
  17. waveboy

    Why pattern testing caused TV interference?

    Dear Engineers, Whilst doing antenna patterns outdoors, we interfered with a nearby television set's reception, quite unexpectedly, -does anybody know why? (don't worry, we are remotely located and it was just the boss's TV and he laughed about it) We were testing at 100MHz to 1GHz. -The...
  18. waveboy

    200Kg door on anechoic chamber.

    Dear Engineers, I would be very grateful if anyone had an answer for why the door on the anechoic chamber i just assembled weighed 200Kg. (This door cost thousands of pounds). The chamber is for testing antennas at 1.8 to 2.2GHz. The antennas are not particularly high power ones. (-Just like a...
  19. waveboy

    Why is smaller cap better for noise filtering?

    Dear Engineers, At Interview, i was recently shown a circuit involving a small cap (about 100n, ceramic) at the output of a voltage regulator (linear one). It was for filtering out noise....it was connected from the output of the regulator to ground. -The input to the regulator was supplied...
  20. waveboy

    S21 on outputs of 4 way splitter.

    Dear Engineers, I recently attended an interview for a Microwave job and was shown a graph of S21 (magnitude in dB) against frequency (2-6 GHz) for the splitter's 4 outputs. (it was not an isolated splitter) I would be most grateful if any Engineer could help with the interviewer's question...

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