EEVblog Electronics Community Forum

Electronics => Projects, Designs, and Technical Stuff => Topic started by: mlloyd1 on October 01, 2024, 09:57:53 pm

Title: why add a resistor in parallel with gas discharge tube?
Post by: mlloyd1 on October 01, 2024, 09:57:53 pm
Looking at a consumer electronic product for US market that uses a GDT paralleled with a 200K ohm/1/2w resistor and that combination is in series with a 15ohm/5w to across the powerline protect the product from surges.
The product is undamaged when hit with surges (tested to about 6KV) and resumes operation afterwards, just as it should.
I understand the reason for the series 15-ohm resistor (basically limits current when GDT fires), but can't explain the 200K in parallel.
My WAG is something to do with maybe helping the tube recover faster after the internal plasma returns to gaseous state after the surge.
But like I said, that's a WAG.
Anybody know the "REAL" answer? ???  :-//
Enquiring minds want to know ....
mlloyd1
Title: Re: why add a resistor in parallel with gas discharge tube?
Post by: Bud on October 01, 2024, 10:35:51 pm
Perhaps to bleed static so it does not build up.
Title: Re: why add a resistor in parallel with gas discharge tube?
Post by: jbb on October 02, 2024, 01:50:08 am
Could it be a bleeder resistor for some capacitor elsewhere in the box?