Delta Pulse

[kt315]

KT315, that is soooo much BULL. Adding a fast recovery diode has NOTHING to do with increasing - or decreasing flyback voltage. NOTHING. The diode will serve to isolate MOSFET capacitance from the coil during flyback, and may allow the use of a higher value of damping resistance and also may reduce flyback settling time, when competently applied.

The diode will never 'see' any more than whatever the breakdown voltage of whatever MOSFET device is being used.

ENOUGH ALREADY.

edit: Adding an FR diode is not a magic bullet.

OK Dear Sir Porkluvr, I see you such big Guru in the f. electronics, please can you answer on following in detailed form:

i need some detailed manufacturing in formatia and guide in oorder to have the best output from delta pulse. i also need to know the best amounts of resistors and capacitors and some points on how to use them.(some point wich makes the best results without knowing expert knowlege and without seeing the signal from.some point like: i have to use capacitors type 100n,250v.
i would like to use two resistors instead of pr1.one for 110*110 coil and the other for 45cm coil.
beside,i need to meseaure these resistors. is it right to remove pr1 and replace it with tow resistors?
i need you to answerthese questions and some others that i may ask later.
i use ic,s with the following numbers and i use all resistors with the 0.01 tolerance.
mc14066BCL(motorolla phill)
irf740 (original IR)
tl062
ne555n(st)
mc14538BCP(motorolla phil)
ne556n(st) or other 556 cmos(haris)
lf357h(original metal can packege)

I NEED COMPLETE GUIDE FILE FOR MANUFACTURING THAT ENPLAINS FOR AN AMATOUR HOW TO MANUFACTURE AND START THE DP COMPLETELY STAGE BY STAGE(STEEL BY STEP)
it,s very important for me to find the hidden and sensitive points which can make us reach the highest power. i also need detailed information in order to manufacture the best coil.

[porkluvr]

Don't act like a child.

[kt315]

Don't act like a child.

you are big Guru.

[porkluvr]

You are a child and a ... big bully.

Have another tankard of ale before you pass out.

[kt315]

You are a child and a ... big bully.

Have another tankard of ale before you pass out.

My post was correct.

Please do not post in this thread again, if you plan to continue shouting i.e. "using bold uppercase and stupid emotions" that is just bl00dy rude and stupid.

[mickstv]

My post was correct.

Please do not post in this thread again, if you plan to continue shouting i.e. "using bold uppercase and stupid emotions" that is just bl00dy rude and stupid.

Hi kt315, can you please refrain from copying my posts and using them in your threads.

[porkluvr]

Wow, you're a trip, KT.

[Tepco]

If someone really want to play with high voltage pulses in this, or any other detector, there are two simple ways, I tried them successfully. First is to replace MOSFET with high voltage IGBT transistor, drive requirement is about the same, 1200v device will clamp at some 1.35-1.4KV. Additional benefit is reduced capacitance, depending on transistor used (no need to be 50Amp rated, some modern smaller device in TO220 package). Disadvantage is increased loss, due to 2-3V saturation voltage. Another method is using MOSFET (can be low voltage type) and high voltage bipolar transistor, like used in CRT horizontal scan stages, in “cascode” connection. Works perfectly, flyback can reach 1.5-1.8kV or even more, capacitance is slightly lower. Disadvantage is somewhat higher current consumption, large base current is needed, due to very low current gain of HV bipolar, usually less than 10. In both cases, some precaution is needed, damping and protection resistor, diodes etc, also very short high energy pulses will tend to deteriorate metal film resistors after some time. I don’t think all this is particularly useful in detector like delta, attempt to speed it up this way, but in some other designs may be interesting to experiment. Most obvious “improvement” in delta can be redesign to some other type input amplifier, to get rid of lF357 (too noisy!), not tried.

[kt315]

Wow, you're a trip, KT.

thank you guys for attention to DP matter, I so did wait scilicet your attention in this thread all this time you are absent and ignoring, but I do not need in additional PR. continue to answer albeit. you can learn me telling about the impedance of MOS-FER in different parts of timing of 'delta pulse' with the HV fast recovery diode and without it.

[kt315]

Wow, you're a trip, KT.

[mohandes]

hi
KT say right or my old friend porkluvr say OK ?
whatever i add this diode in my new PCB that i design it.
KT what is the meaning of FFFFFFFFFFFFFFFFFFFFFUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUU ?
regards

[turboaleks]

Maybe something like this: http://www.youtube.com/watch?v=NhF2v35qU2c

[mohandes]

Maybe something like this: http://www.youtube.com/watch?v=NhF2v35qU2c

[porkluvr]

Here is a virtual comparison of using a diode and not having one. I see some apparent difference between the two circuits' performance, but how or if that equates to improved target detection can only be determined in the field .

It looks to me like adding the diode will cause flyback to decay much faster in the first few microseconds. If adding a diode works out for builders being able to sample earlier than they could have otherwise, that is a good thing. And if you can use a higher damping resistance than before, that should also allow a stronger signal to be seen at the receiver input.

I don't think the diode would need to have a 1500V breakdown voltage (although for all I know, the STTH1210 might still be the best choice for some reason or another), but it would be a bad idea to use something with a lower breakdown voltage as compared to the zener voltage of whatever MOSFET is being used.

In case it is not obvious, what I did with the progression in the photo was start with the "big" picture, and then zoom in sequentially towards the last few microseconds of the flyback's settling. Note that the 176us point is about 14us after the end of the transmit pulse.

[kt315]

how long was PULSE WIDTH in your interpetation? I ask because there has not deep sense to use the diode at range before 150us, but has after, near to 500us.