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Recent content by lw1ecp

  1. L

    [SOLVED] Creepage, clearance, and insulation types

    FvM, you're right! My main interest was how to connect the "class" with the creepage value but I've just found that in ECMA-287. Thank you!
  2. L

    [SOLVED] Creepage, clearance, and insulation types

    Just to close the subject, I am posting what I've found. Creepage applies to both type I (with earth cable) and type II (without). The difference is: for type I, minimum creepage is 4mm for the most common situations, and 4+4mm (double insulation) or 8mm (reinforced insulation) for type II...
  3. L

    How to minimize or eliminate emi noise?

    My recent experience: an Arduino connected to (and powered by) PC via USB, and only the (-) lead of a passive power supply connected to Arduino's ground, no other connection. Every time the PSU was plugged or unplugged on the wall, communication was lost. Removing the (-) lead there was no...
  4. L

    [SOLVED] Creepage, clearance, and insulation types

    Hi! I already know the definitions for creepage, clearance, type I and type II products. My doubt is: are creepage and clearance requirements applicable just to class II products? Can you relax creepage and clearance strictness thanks to the earth cable in class I? Thank you!
  5. L

    High side switch - minimize power dissipation.

    Re: High side switch - minimalize power disipation. Another idea: when your input is not zero, will it always be 40V or at least >35V? If this is the case, then you can simplify your circuit. Just one NMOS, drain to +25V, source to load, 10k resistor from input to gate, 10V zener gate-source.
  6. L

    Wideband optical communication

    I plan to add a 100% failsafe protection against lightning to my cable modem and the equipment beyond. The idea is routing up- and down-stream signals through separate ~1m optical fibers. Both will have an emitter (laser or LED) and a photodetector at each end, plus the necessary gain blocks...
  7. L

    High side switch - minimize power dissipation.

    Re: High side switch - minimalize power disipation. About losses in the transitions: do you need to meet given rise and fall times? Maybe resistors to the MOS gate are too high. I think just reducing R9 from 30 to 10k will still give adequate Vgs to turn the transistor on, but its turnoff time...
  8. L

    UHF RFID at 922.5 MHz

    Sorry, you mean you need to design a microstrip line to match those impedances to 50 ohm? - - - Updated - - - Check this archived version: https://web-beta.archive.org/web/20140927032701/http://nxp.transim.com:80/rfid/design.aspx I can't see if it works for I have some problem with JavaScript...
  9. L

    555 timer as square wave generator

    aliyesami, here you have a handy calculator (it is quoted in yadavvlsi's link): https://www.ohmslawcalculator.com/555_astable.php The bipolar and CMOS versions of the 555 generate a frequency and duty cycle that are quite independent from the supply voltage. So dont' worry porting a 9V schematic...
  10. L

    555 timer as square wave generator

    CMOS versions of the NE555 can run on lower voltages. E. g. the TI LMC555 specifies "1.5V Supply Operating Voltage Ensured".
  11. L

    A question about battery charging voltage

    If this is helpful for you, the battery on my car says "Do not exceed 14V charging voltage at 1500RPM". This is a regular maintenance-free model. I recall a previous one I had asked not to exceed 14.4V. And power car audio ICs such as the TDA2002 are rated at 14.4V so I imagine the IC...
  12. L

    pure sine wave inverter

    Just an idea: I once thougt of making a sinewave inverter this way: a quick-and-dirty unregulated DC-to-DC, suplying high voltage DC to a switching power stage, driven by a PWM created from sine values. An inductor in series with the output smooths the pulses into a continuous sine.
  13. L

    [SOLVED] Strange problem with high frequency shunt

    Sorry I disn't close the thread earlier. It is solved. It is the skin effect that distorts those HF waveforms. The lesson I learnt is: don't use ferromagnetic materials such as nichrome for HF shunts because their high permeability reduces their skin depth much more than other materials, and as...
  14. L

    How to Convert dbc to db

    I suppose you are talking about "decibels relative to carrier". You can find it used to measure the noise power density at a given offset from the carrier. E.g. if the noise power 10kHz away in a 1Hz bandwidth is 80dB below carrier power, then you can say SSB noise there is -80dBc. There's no...
  15. L

    equvalent of MPS102 $ 2n5485

    ehsanjayjay, I'm very sorry, I have just realized you had posted the schematics a long time ago. I see the FETs are used as simple analog switches. There is nothing special with them. A funny thing in the hand drawn schematic is Q3=2N5485 and Q4=MPF102, why not the same type? Looking at how Vss...

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