MightyOhm.com

Yes, the diodes are the same, and the 555 is a TLC555 and I am build of one of these resin boards with metal contacts to solder (I do not know the name of it). Unfortunately no access to an oscilloscope :( The first thing I am going to do is to replace the inductor with a different one. I found this...

UPDATE 2: I decided to remove R8 (short circuit), and when I set the 10ohm pot to 4.2ohm, I measure 30.1v with the 100Mohm set of resistors. Now the tube is being activated by the background radiation, but I am not sure what other modifications I can do to get a big higher voltage. If I reduce more ...

UPDATE: I put 10 x 10Mohm (in total 100 Mohm) resistors in serial, plus the fluke. When the pot is to the maximum (or minimum resistance ;)) it reads 20.12v. So I guess I am generating only around 200v. Any tips on how to increase the HV voltage? Maybe reducing the resistance of R8? I will try this ...

I am trying to use a MJE13007... but I did not manage to make it work yet!

Hello Jeff and all the people here, first, great job in your blog and specially with the Geiger kit. I have to say that I did not order it so I do not expect any support. I wanted to make use of the HV supply to drive a SBM-20, but my first attempt did not work (maybe the tube is broken? is there so...