Good vid Mark & thanks for the link... There was only a couple left but I got one :) Cheers John

im considering building one, but don't know what voltage i should use for the 3x 100uF electrolytic capacitors...

thank you for help, i cant connect because i didn't check append CR LR in termite and spend hour...

What is the maximum counting rate per minute this device allows?

Man you build fast :) Thumbs up!

Nice work. I have a question, I own a GQ geiger counter that with a glass tube. I want to upgrade it to SBM-20 tube as well but wandering how should I calibrate it.

@DextersTechLab

5 жыл бұрын

Just watch my video on how to do it! kzread.info/dash/bejne/poqC0dyKndrZd6w.html

With the GM tube powered at 450V, is there a risk of painful electric shock if you touch the tube while it's switched on? Or is the current limited so you'll only feel a tingle, if anything?

@DextersTechLab

5 жыл бұрын

You would feel an unpleasant nip.

HV value is : GM tube voltage[V] = 5.7 x hvg , so with yours 60 should be 340v not 426v? for my tube i need 450v so i set 79 value, ( i dont have hv high impedance probe so I made voltage divisor (3x 33Mohm) 99Mohm, and easy measure voltage , my multimeter internal impedance is 10mohm so 100/10=10 so reading will be 10 times lover, and exactly showing 45V.)

Great video! Question: Have you tried this Geiger counter with Americium 241? (smoke detectors stuff) I understand is it mainly an alpha emitter, but it also emits some gamma radiation. ¿Could this counter detect that 1%? ¿And from what distance?

@DextersTechLab

7 жыл бұрын

+Munrais You should see some activity with the sbm20 tube up close as in nearly touching, but not much. You are correct about it being an alpha emitter. You ideally need a mica windowed tube. I test my am241 source on such a probe in this video kzread.info/dash/bejne/oJ6fo82dadXSn7g.html These mica windowed tubes can be connected to this counter very easily.

@slick4401

7 жыл бұрын

Thanks a bunch.

Very interesting, where do you store your "hot" samples? I suggest some kind of fire safe, no?

@DextersTechLab

3 жыл бұрын

I have a small lead container with walls about 30mm thick. It keeps everything safe

What impedance is your probe ? I measured 196 with a 600v meter , impedance 5m ohm

@DextersTechLab

6 жыл бұрын

the probe is a Tes-Tec HVP-40 and has a 1G ohm input impedance

What kind of enclosure did you get for it? Did you make the box yourself or were you able to find something pre-made that fit it properly and only required some modification?

@DextersTechLab

8 жыл бұрын

i found an old unused project box in my junk pile, i'm sorry i did not document it as i had to get it finished and sent over to spain. It was a small ABS box probably from RS or Maplin.

@Hirobian

8 жыл бұрын

Ah, thank you for the info. I am considering purchasing a Geiger counter of this model and I was concerned about the lack of a proper case. It's always best to protect electronics from damage and I have noticed comments that the detector tube can give a nasty shock. I'll do some research on these enclosures, I think I may be able to find some locally, there's bound to be a place that sells components and stuff. Perhaps a hobby store? I shall see. :)

If you turn it on while holding the mute button it'll use a clicking sound if you like that more

@DextersTechLab

8 жыл бұрын

+FRR thanks for the tip!

@FozziesRandomReviews

8 жыл бұрын

+DextersLab2013 Sorry, it's the clear button!

@das250250

6 жыл бұрын

What is the impedance of your probe ? I measured 196 volts with a 5mohm tester

That was the quickest kit build ever hahaha

But is it any good?

@DextersTechLab

8 жыл бұрын

+Euro Cannabist Of course it would depend on what you want to use it for, thinking of the capabilities of the SBM-20 tube, but as far as the hardware goes it works very well.

it's time for the seller to upgrade the unit. It's over 6 years old design.

@dvdrwsor

7 жыл бұрын

Can you suggest a good design please?

@benbaselet2026

6 жыл бұрын

How would you upgrade it? It's a radiation monitor, it displays counts and sieverts, just like radiation monitors have for many decades... A fancy color screen with smiley faces on it?

won't the tube shock you

@DextersTechLab

8 жыл бұрын

+Agent Office if i hadn't put it into a box... yes ;-)

@ankdoeslego9731

6 жыл бұрын

DextersLab2013 wouldn’t the voltage drop so low upon touching it that one feels nothing?