radiation meter November 2011

Equipment, circuits, projects, procedures

Postby alefbe » Fri Apr 06, 2012 12:00 am

Hi,

with your last suggestion (use of an oscilloscope...) I solved the issue. The signals from the PC were passing through the BOB and were present at the Rx pin of the board. Then I went on checking if
the signals were reaching pin2 of the microprocessor, but to do this I had to remove the micro from its socket and could then detect the signals on pin2 of the socket. I was then suspecting as you were suggesting a faulty micro. But when I replaced the micro in its socket to my surprise everything worked and I was finally able to change the L value. It was obviously a bad contact between the micro and the socket.
Thank you all for your help.
alefbe
 
Posts: 5
Joined: Thu Jan 02, 2014 10:47 am

Postby teemo » Sun Apr 08, 2012 12:00 am

Hello,

How to connect 2n3055 as sensor?
teemo
 
Posts: 2
Joined: Thu Jan 02, 2014 10:47 am

Postby thijsbeckers » Tue Apr 10, 2012 12:00 am

Good to see it worked out, alefbe. Glad to be of help.
thijsbeckers
 
Posts: 1134
Joined: Thu Jan 02, 2014 10:37 am

Postby thijsbeckers » Tue Apr 10, 2012 12:00 am

TeemoHello,

How to connect 2n3055 as sensor?


This is how I did it:
Attachments
110538-2N3055-montage-a.jpg
110538-2N3055-montage-b.jpg
thijsbeckers
 
Posts: 1134
Joined: Thu Jan 02, 2014 10:37 am

Postby ben22 » Sat Jun 09, 2012 12:00 am

Hi, I am also building the radiation meter from your kit.
I tried to read a signal without shielding the photodiode to see if it counts anything. is it normal that ithout shielding, it doesnt count at all?
ben22
 
Posts: 13
Joined: Thu Jan 02, 2014 10:47 am

Postby thijsbeckers » Mon Jun 11, 2012 12:00 am

Ben22I tried to read a signal without shielding the photodiode to see if it counts anything. is it normal that ithout shielding, it doesnt count at all?

Without shielding and in a lit environment the amplifier stages are likely to be overloaded, resulting in no counting at all. So it sounds normal.
You could try to shield the sensor from most light by enclosing it in your hand or wrapping it in black tape and then power on the circuit.
thijsbeckers
 
Posts: 1134
Joined: Thu Jan 02, 2014 10:37 am

Postby ben22 » Sat Jun 23, 2012 12:00 am

is there anyway to test the circuit without having any radioactive sources?
ben22
 
Posts: 13
Joined: Thu Jan 02, 2014 10:47 am

Postby thijsbeckers » Mon Jun 25, 2012 12:00 am

Ben22is there anyway to test the circuit without having any radioactive sources?

Yes, there's always some background radiation. Using the BPW34 in a properly shielded enclosure you should be able to calibrate your radiation meter to 0.33 counts per minute, using the threshold setting in the software. A longer sample period is required for this, of course. 10 minutes being an minimum.
thijsbeckers
 
Posts: 1134
Joined: Thu Jan 02, 2014 10:37 am

Postby ben22 » Sat Jun 30, 2012 12:00 am

.
ben22
 
Posts: 13
Joined: Thu Jan 02, 2014 10:47 am

Postby thijsbeckers » Mon Jul 02, 2012 12:00 am

If you have a scope, you can have a look at the output signal on K4. If that looks like there is a 'giant' 50/60Hz ripple present, you should definitely look into grounding your circuit.

The thing is, if you overload the sensor, the output voltage is so high that the uC doesn't count anything. The other thing that stops the uC from counting is of course no signal present or the signal is below the threshold...

What worked best for our prototype is shown in the attached picture; i.e. a metal enclosure grounded properly to the circuits ground, the amplifier PCB inside, the display outside the enclosure. The sensor signal is amplified a lot, so it's quite sensitive to any disturbance.
Attachments
110709-55.jpg
thijsbeckers
 
Posts: 1134
Joined: Thu Jan 02, 2014 10:37 am

PreviousNext

Return to Test & Measurement

Who is online

Users browsing this forum: No registered users and 1 guest