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  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...
  16. L

    equvalent of MPS102 $ 2n5485

    Maybe the problem is not that you have used wrong equivalents. Sorry for my insistence, but we could probably be more helpful if you post the circuit. Don't you know how to do it?. Click Manage Attachments -> Add Files -> Basic Uploader -> Examine (there you navigate your PC to the desired file)...
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    equvalent of MPS102 $ 2n5485

    ehsanjayjay, the old MPF102 is a very, very ambiguous part, the datasheet says Idss can be anything from 2 to 20mA, and expect any cutoff (pinchoff) voltage from about -0.5 to -8V, and transconductance from 2 to 7.5 millisiemens. Aghhhh!!! This is what one could call an out-of-control process...
  18. L

    PIC-LCD-PC interfase

    paulfjujo, many thanks for your hints!. I also fear VB would not be fast enough, what seems to be the strobe is 1us-wide. And even if it could do the job, I would still have to know how to differentiate the read from the write operations, and command from the data operations. Working with 4 bits...
  19. L

    equvalent of MPS102 $ 2n5485

    Sorry, I can't find a datasheet for "kt315". Maybe there is a mistake in the code?. In case you read it on a real transistor, not in a schematic, please take into account most Japanese transistors omit the first characters, e.g. units beginning with "K" actually begin with "2SK". "2SK" means...
  20. L

    equvalent of MPS102 $ 2n5485

    Same procurement problems here in Argentina... BF24* BF25* MPF102 2N3819 2N548* are very similar, seem to use the same chip. Differences among the members of a same family (e.g. BF244A B C; or 2N5484 5485 5486) are Idss (the Id for Vgs=0) and Vgs(cutoff). There can be an impressive parameters...

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