Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

How can I improve this GDT waveform?

Status
Not open for further replies.

boylesg

Advanced Member level 3
Joined
Jul 15, 2012
Messages
995
Helped
5
Reputation
10
Reaction score
5
Trophy points
1,298
Location
Epping, Victoria, Australia
Activity points
11,537
GDTSecondaryWaveforms.jpg

Based on Steve Ward's min STTC design: https://www.stevehv.4hv.org/SSTC5/miniSSTCfnlsch.JPG

These are the waveform generated by the two secondary windings of my GDT with the probe on one end of the primary and the GND clip on the other end.

I have a 6.8uF greencap in series with the primary coil of the GDT.

The inductance of the primary coil and one of the secondary coils is 1.34mH. But for some reason the other secondary has a slightly lower inductance of 1.26mH. It might have something to do with the fact that I used thin hook up wire to wind the GDT and not magnet wire. It seemed more convenient to have the windings colour coded but it is also harder to get the windings tight.

But there are two problems that I can see.

1) There is a lot of ringing going on here. Is that likely to be a problem?

2) My vertical scale is 0.5V and my probe is on x10 so I put the peak voltage at 5V and that is too low. So what is the preferred way to increase the voltage?

a) Increase the value of the series capacitor?
b) Reduce the number of windings?
c) Increase the number of secondary windings?
 

KlausST

Super Moderator
Staff member
Joined
Apr 17, 2014
Messages
19,473
Helped
4,306
Reputation
8,617
Reaction score
4,261
Trophy points
1,393
Activity points
129,124
Hi,

try to adjust trigger level for a single signal view (now it triggers at least at two different points of signal)

What frequency is your signal?

***
You could try with R-C snubber circuit to supress ringing.

Klaus
 

boylesg

Advanced Member level 3
Joined
Jul 15, 2012
Messages
995
Helped
5
Reputation
10
Reaction score
5
Trophy points
1,298
Location
Epping, Victoria, Australia
Activity points
11,537
Hi,

try to adjust trigger level for a single signal view (now it triggers at least at two different points of signal)

What frequency is your signal?

***
You could try with R-C snubber circuit to supress ringing.

Klaus

About 106kHz of there abouts.

Steve didn't have any RC snubber with his design so I suspect there is an issue with the way I have wound my GDT.

The first thing I need to do is to make it with magnet wire , get the coils nice and tight and get the inductance of all the coils equal.


I presume the low voltage might have something to with leakage inductance probably due to the way I wound the GDT where the coils are not tight around the toroid?

Does leakage inductance have anything to do with the severity of ringing?
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top