Why the preference of the SBM-20?
Re: Why the preference of the SBM-20?
Those specs are nearly identical to the SBM-20. I'll have to get one and check it out. Thanks for the info!
Jeff Keyzer
http://mightyohm.com
http://mightyohm.com
More sensitive tube?
I am a watchmaker and built the kit with the intention of identifying radioactive dials and hands. Many older watches used Tritium and VERY old watches used Radium to make the dials and hands glow in the dark. The SBM-20 tube is able to pick up Radium (the stuff gives off alpha, beta and gamma radiation so it's not too surprising I guess...) but doesn't make a peep for Tritium. Tritium gives off low energy beta radiation, so I'm guessing the tube is just not sensitive enough. Any suggestions for alternatives?
Thanks!
_john
Thanks!
_john
Re: Why the preference of the SBM-20?
See if you can find an LND-712 tube, it should work with the kit and has an end window for alpha/low energy beta.
Jeff Keyzer
http://mightyohm.com
http://mightyohm.com
Re: Why the preference of the SBM-20?
Thanks for the tip, I'll try to track one down and give it a shot.
Regards,
_john
Regards,
_john
Re: Why the preference of the SBM-20?
Thanks, I will design this into my surface mount design as a capable alternative. I'm almost there!
Re: Why the preference of the SBM-20?
I picked up an Anton 6107 on fleaBay for around $52 with shipping. Modified the kit, reversing the terminals so it can poke out on the left side. Replaced the anode resistor with 1 M ohm, and the VR with a 20 ohm pot so I could get it up to 700 V. Seems to work quite well. With an AM241 source (from smoke detector) held close it beeps almost continuously. It does pick up something from a small tritium tube, but just barely. Background rate is much lower than the SBM-20.
William
William
Re: Why the preference of the SBM-20?
OK, I got the LND-712 tube; is there anything special I need to think about when modifying the kit for it? Is there a positive and negative to the connections (I'd guess not)? Can anyone recommend a clip or good way to mount the tube to the board?mightyohm wrote:See if you can find an LND-712 tube, it should work with the kit and has an end window for alpha/low energy beta.
Thanks again!
_john
Re: Why the preference of the SBM-20?
John,
There is a positive and negative terminal on all geiger tubes. The negative side of the LND-712 is the wire connected to the outside metal tube.
Take a look at the Sparkfun Geiger Counter kit, they use an LND-712. That kit might give you some mounting ideas.
There is a positive and negative terminal on all geiger tubes. The negative side of the LND-712 is the wire connected to the outside metal tube.
Take a look at the Sparkfun Geiger Counter kit, they use an LND-712. That kit might give you some mounting ideas.
Jeff Keyzer
http://mightyohm.com
http://mightyohm.com
Re: Why the preference of the SBM-20?
Great, thanks! I surely would've noticed the + and - on the circuit board after removing the SBM-20, but thanks for clarifying the polarity of the LND-712.
SparkFun's "mount" looks, um... functional, but I guess it'll work if I can't come up with anything better. Thanks again!
_john
SparkFun's "mount" looks, um... functional, but I guess it'll work if I can't come up with anything better. Thanks again!
_john