Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
hi,Hi.
How can floating plain sinusoidal 230VAC 50Hz from a power transformer secondary be converted to 50Hz pulses of about 0.01mS duration ?
Thanks
If the transfomer output is used for other purposes and is not grounded then you would need to use an isolator, such as an opto coupler to generate the pulse. Connect the input of the opto coupler through a diode to the transformer output with a resistor to limit the current to the opto coupler's rated input. The opto coupler output can be used trigger a 0.01s monostable (one-shot).Hi.
Floating means none of the power transformer output winding terminals or lines is grounded, nor center tap neutral.
It is the output transformer of a DC to AC inverter, to be used for nothing else than to convert its AC into pulses for a device that operates with pulses and not with sinusoidal AC.
Miguel
Works, but I don't think the 6V2 zener will ever conduct in the reverse direction (foward direction of the opto emitter) since 6.2V is much higher than a typical emitter's forward voltage. You could split the resistor into two series resistors and connect the zener at the junction of the resistors. That way it would provide a clipped sine-wave signal to the opto emitter input.hi Carl.
The way I have used the opto method is to have the series resistor, you have stated, but a zener diode connected in parallel with the opto emitter.
The zener voltage chosen to suit the transformer secondary voltage, a 12Vac, say a 6V2.
This gives a good waveform on the opto collector and it also protects the opto against reverse overvoltage.
If the transfomer output is used for other purposes and is not grounded then you would need to use an isolator, such as an opto coupler to generate the pulse. Connect the input of the opto coupler through a diode to the transformer output with a resistor to limit the current to the opto coupler's rated input. The opto coupler output can be used trigger a 0.01s monostable (one-shot).
P.S. And why are you against the deciBel?
The decibel is not intended to replace the volt. It is a logarithmic representation of power ratios (but is also often used to represent voltage ratios). The reason for using it is that a logarithmic measure is often much easier for humans to interpret, especially for relative measurements. It's also a sort of simple shorthand way of expressing such ratios. For example a filter rolloff of 12db/octave is simplier than saying a rolloff factor of 0.2512 per octave. Or it's easier to say an amp has 75dB of gain than a gain of 5,623.The already isolated transformer output is not used for any other purpose than obtaining 230V 50Hz pulses, it has no grounded side.
In that case you ground one side of the output and use the suggested comparator, one-shot circuit.
I was expecting something more in the line of a dimmer/scr type of circuit suggestion where the scr conduction somewhere at the positive peak of the AC would capacitively emit the pulse (to be polished)
That's probably more complex than using a comparator. And you would still need a one-shot to generate the .01ms pulse.
---> Feel that the antique attempt to substitute a perfectly good and world recognized unit as the Volt is senseless. The decibel is absurd in 2008 and makes all innecessarily convoluted and complex. All expressed in decibels can be perfectly expressed without it and with no confusion to learners.
AC couple the sinewave and you don't need the half wave rectifier.hi,
Half wave rectifier, zero crossing comparator and a monostable.![]()
AC couple the sinewave and you don't need the half wave rectifier.![]()
---> Feel that the antique attempt to substitute a perfectly good and world recognized unit as the Volt is senseless. The decibel is absurd in 2008 and makes all innecessarily convoluted and complex. All expressed in decibels can be perfectly expressed without it and with no confusion to learners.
I believe your chances of eliminating it's useage are about the same as eliminating the use of English units of measure in the U.S.
Part of the reason dB's are useful is that, since they are logarithmic, they can be simply added in your head to get a total. Thus, for example, an amp stage with 32dB gain driving an amp stage with 36dB gain will have a total gain of 68dB. You don't have to multiply 39.8 by 63.1 to get the total gain of ~2,500.Try doing the power budget calculations for a microwave radio link using your "learner friendly technique" and you will see why dB are so useful.
Ron. Couldn't agree more. That's why I suggested it in my June 26th post, but guess most people missed it.Am I missing something here? If the output of the transformer is used for no other purpose, why can't one terminal be grounded?
This is not intended to be contentious, but if you suggested it, it was in a roundabout way, unless I missed it again when I reread your posts.Ron. Couldn't agree more. That's why I suggested it in my June 26th post, but guess most people missed it.
It was sort of buried in the quote from Ethernet:This is not intended to be contentious, but if you suggested it, it was in a roundabout way, unless I missed it again when I reread your posts.