First eBay haul of 2020 - Project Gizmo!

This month I have taken delivery of my first eBay haul of components for 2020! This months selection of stuff primarily concerns my latest project ‘Gizmo’ (the name of my Yorkie and a reference to ‘Gadget’, the first nuclear bomb), an attempt to power a Geiger Muller tube and detect background beta & gamma radiation! I then hope to incoporate the circuit into a proper PCB project and have the radiation count logged to a website so it can be displayed live!

The first order was a special one! A genuine Polish Cold War DP-66 Geiger counter probe! This probe was used to measure beta and gamma radiation by the Polish army during the Cold War, thankfully nuclear war never happened between the east and west and now these Geiger counters are collected by enthusiasts all over the world.

DP-66 Geiger Counter Probe

The probe contains three Soviet Geiger Muller tubes; an STS-5, a DOB-50 and a DOB-80. The STS-5 is removable, but the DOBs need to be cut from the probe board. With that said, I think I’ll only use the STS-5 for my experiment as the probe is too nice to take apart, I’ve decided. The DP-66 probe cost £30 and was from ‘beastore2’.

Before ordering the DP-66 probe, I nabbed a cheap NOS STS-5 Geiger Muller tube from a seller in Ukraine.

STS-5 Geiger Muller tube

Unfortunately, the tube still hasn’t arrived, the seller has supplied a tracking number, but the item still hasn’t seemed to have left Ukraine yet! The tube cost £13 and was from ‘tubesandsound’. Until I get my tube, I’m not leaving them feedback or buying anything else from them.

I was browsing eBay one night and came across a listing for a rare high voltage flyback transformer, an HP 9100-3927, made by Pennitran in Bellefonte, PA, USA. The transformer I got was NOS, but I think these would have been used in old-school CRT oscilloscopes or other test gear.

HP 9100-3927 transformer

Unfortunately, my tests with this transformer were pretty unexciting and I got very short purple arcs out of it. The transformer cost £23 and was from ‘test-equip’.

Next up, I ordered a pair of genuine Vishay IRFPC60BF N-Channel MOSFETs, rated for 600V at 16A, packaged in TO-247AC. I was quite confident these were genuine, as they were from a reputable seller. I have ordered MOSFETs in the past which I believe to be fakes.


The MOSFETs were won in an auction for £4.99 and were from ‘electronic_trade_sales’.

One component I find myself regularly short of are ceramic caps! I’m always making circuits that require a certain value, but I end up having to substitute values or put capacitors in parallel. Well, now I have a boxed set of 450pcs MLCC 50v capacitors with values ranging from 10pF to 100nF.

50V MLCC capacitors

The capacitors cost £6.29 and were from ‘michaelrobertson-52’.

I'm currently attempting to wind my very own 400V ferrite switching transformer to power my STS-5 Geiger Muller tube, although the chance of failure I reckon is pretty high, so I decided to buy a ‘lucky bag’ of mixed transformers just in case.


The bag contains numerous transfomers of varying sizes, including two mains transformers and several different types of ferrite switching transformer. Hopefully there’s something of use to me. This bag cost £8.50 and came from ‘anonalouise

And finally, I ordered 5x 1N5388B 200V 5W zener diodes for my Geiger counter project. I will connect two of these zeners in series to provide a crude, but stable 400V DC supply for the STS-5 GM tube.

The zener diodes cost just £2.49 and were from ‘it_tech_uk’.

That’s all for now, I’m very excited to get my transformer wound and see if I can generate a reliable 400v DC supply, if I do, I’ll be able to test it on the STS-5 tube and see if I can get any audible clicks of radiation out of it! To keep up with what I’m doing, please feel free to follow me @ChrisElison on Instagram and Twitter!