Minipulse Plus Rev My time has come!

[green]

What do you mean by hot wire insulation?I measure with score ground to TP5 and probe to R4 (near trimmer side),im confused...

Here is a video as godigit1 said ch1 yellow (probe to R4 trimmer side and ground TP5) and ch2 (probe to TP3 ground TP5)...With 2,2 kohms pot

Also notice on R4 hot side voltages goes up to 600V...I thing im violating irf840 characteristics?

Hot wire is the coil wire connected to MUR460 diode. I use twisted pair so it is easy to clip probe to wire coating(insulation). Coax center wire has a thicker coating, might be harder to clip to. Maybe less signal.

I use a 11N50M2 MOSFET rated minimum break down 500V same as IRF840. I get 550V and you get 600V. Don't know how much higher than minimum to expect.

[mushaba]

... scope probes connected to Tx hot lead and hot lead insulation. Amplifier out is most important. I like looking at coil decay and amplifier out when adjusting damping. Is underdamped, overdamped or critical damped best? Scope probe connected to Tx hot lead can have a small effect on damping so I usually connect the probe to the wire insulation..

What do you mean by hot wire insulation?I measure with score ground to TP5 and probe to R4 (near trimmer side),im confused...

Here is a video as godigit1 said ch1 yellow (probe to R4 trimmer side and ground TP5) and ch2 (probe to TP3 ground TP5)...With 2,2 kohms pot

Also notice on R4 hot side voltages goes up to 600V...I thing im violating irf840 characteristics?

[green]

Well here are mine readings (this time dumping resistor 1610Ohms)

[ATTACH]45929[/ATTACH]
[ATTACH]45930[/ATTACH]

How do they look??Comparing to the photo you've sent me mine has a steep rising edge with something weird on the top left edge..

Look good. The pictures in reply#22 showed damping adjustment but the Tx current was a lot lower than it should be. Fixed the problem and recorded again, scope probes connected to Tx hot lead and hot lead insulation. Amplifier out is most important. I like looking at coil decay and amplifier out when adjusting damping. Is underdamped, overdamped or critical damped best? Scope probe connected to Tx hot lead can have a small effect on damping so I usually connect the probe to the wire insulation. Also don't have to remember to switch probe to X10.

[godigit1]

Ok look at Post # 36 in the thread right below MPP Op amp is vastly improvable.
Thats 3 different op amps Look at the before shots as that is stock MPP. All of these shots are just slightly underdamped as my coil was stable there and got better sensativity.

[godigit1]

Im still learning so im not a expert with the scope yet. But y our wave form in Post #29 doe not look correct Its like your coil is staying charged at shut off. Top of the wave form should be sharp voltage drop.
Also you are looking at the coil flyback. to damp you need to look at the op amp out TP3.
Put both channels up and that way you can see both as you adjust. But tp3 is what you adjust the ringing away from.
1610 ohms seem way high at least for all m y coils it would be. Im damping from 375 to 800 or so depending on the coil.
Try damping to both signals and play with a desired target while you do it that way you can see the effects of over and under damping.

[mushaba]

I'm not expert, but difference between 10uS and 15uS is sooo small.
I feel that different solder quality and fluxy residues on PCB could steal a microsecond or two.
Clean board from flux. Nice and clean.
Also, I never considered the effects of sockets vs directly soldered chips.
I never worried much about soo small sample delays.
Just thinking out loud some things that might be considered when dealing with such tiny margins.
Also what kind and how long wires to delay pot. Don't really know, but not sure what effect if any these things mentioned might have on depriving you of a few microseconds here and there.
Otherwise tweak the component values to get the results you want.

Yes will do that,i will clean flux ....I should be able to take the correct test measurments and after that i will make a very nice construction and housing for a finish.

[mushaba]

Some scope pictures adjusting damping. Two different Tx coils, scope lead clipped to Tx hot lead insulation.

Well here are mine readings (this time dumping resistor 1610Ohms)




How do they look??Comparing to the photo you've sent me mine has a steep rising edge with something weird on the top left edge..

[mushaba]

Just out of curiosity, which 4538 chips did you use? I mean the whole name. The small discrepancies could be result of which type used.
CD4538, hcf4538, rca4538, mc14538 etc, then bp, bcp, etc. Don't know for sure, but try swapping out for different manufacturers if you have any in stock.

Unfortunatelly i dont have stocked another 4538...Mine is the HFC type by St came from diydetectors.co.uk within the kit.


As i see from image below its a "faster" type than MC14538BCP ..

[mushaba]

Im glad you figured it out.
Almost every question we can has been ask before its just a question of finding the posts.
There is a thread where Tepco If memory serves put a short film of the damping resistor adjustment. Its a old thread so I havent been able to find it.
You want to adjust your damping pot to you see the ringing then adjust it until the ringing just disappears.

Thanks godigit1,took me sometime,learned a lot of things and come down to some conlcusions.As for ringing the only time i saw on the scope "ringing" i was monitoring TP3,a very helpfull image on green's post took measurments at hot side of the coil.

As far as the gain pot .
Maybe there is a resistor or pot not right??

Happy happy happy!!!!!!!!!!!!I dont know if it is correct but i cut one side of the pot and bang!

[dbanner]

I'm not expert, but difference between 10uS and 15uS is sooo small.
I feel that different solder quality and fluxy residues on PCB could steal a microsecond or two.
Clean board from flux. Nice and clean.
Also, I never considered the effects of sockets vs directly soldered chips.
I never worried much about soo small sample delays.
Just thinking out loud some things that might be considered when dealing with such tiny margins.
Also what kind and how long wires to delay pot. Don't really know, but not sure what effect if any these things mentioned might have on depriving you of a few microseconds here and there.
Otherwise tweak the component values to get the results you want.

[mushaba]

Just out of curiosity, which 4538 chips did you use? I mean the whole name. The small discrepancies could be result of which type used.
CD4538, hcf4538, rca4538, mc14538 etc, then bp, bcp, etc. Don't know for sure, but try swapping out for different manufacturers if you have any in stock.

Thanks dbanner for your reply,currently I'm at work tommorow I ll be at my homeshop and I will look it for sure.I bought the kit (pcb+parts) from diydetectors cause TME was out of stock to some parts..I also believe that timmings issues are due to ic quality..We should use cmos ic's ...I've checked on arrival all parts except the ic..

[dbanner]

Just out of curiosity, which 4538 chips did you use? I mean the whole name. The small discrepancies could be result of which type used.
CD4538, hcf4538, rca4538, mc14538 etc, then bp, bcp, etc. Don't know for sure, but try swapping out for different manufacturers if you have any in stock.

[mushaba]

Some scope pictures adjusting damping. Two different Tx coils, scope lead clipped to Tx hot lead insulation.

Thanks green for the usefull info.I used TP3 (I think) for the damping procedure,my waveform looks mostly like the o e down at right...
Tommorow I will try to dump again and measure from the "Hotpoint" of the resistor...Thanks again for your response!Do you think with better coil I can achieve more precise timmings?

[green]

Some scope pictures adjusting damping. Two different Tx coils, scope lead clipped to Tx hot lead insulation.

[mushaba]

As for the extra 6us I believe is the time that the ic goes from a level to another,can it be tweaked to be accurate?