Images Scientific Instruments GCK-01-01 Analog Geiger Counter Kit Instruction Manual
- September 23, 2024
- Images Scientific Instruments
Table of Contents
- GCK-01-01 Analog Geiger Counter Kit
- Specifications:
- Product Usage Instructions:
- Detection of Radioactive Particles:
- Digital Output Interface:
- Standard Output Indication:
- Headphone Usage:
- Finding Radioactive Sources:
- Q: How do I know if the Geiger Counter is working
- Q: Can I use the Geiger Counter without headphones?
GCK-01-01 Analog Geiger Counter Kit
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Specifications:
- Model: GCK-01-01
- Manufacturer: Images Scientific Instruments Inc.
- Address: 109 Woods of Arden Road Staten Island NY 10312
- Contact: Tel 718.966.3694, Fax 718.966.3695
- Website: www.imagesco.com
- Features:
- Detects: Alpha, Beta, Gamma, and X-Rays
- Digital Output for interfacing with PC or microprocessor
- External Power Jack
- Headphone Jack
- Standard Output with clicks and LED indication
- Geiger Tube: GMT-01 (LND 712)
- Power Source: 9-Volt battery or external power with a 2.5mm
jack
Product Usage Instructions:
Detection of Radioactive Particles:
The Geiger Counter detects Alpha radiation above 3.0 MeV, Beta
radiation above 50 KeV, and Gamma radiation above 7 KeV. Connect
the power source and turn on the device to start detection.
Digital Output Interface:
Use the digital output jack to connect to a PC or microprocessor
for data processing. Make sure to use the appropriate adapter for
interfacing.
Standard Output Indication:
The Geiger Counter provides audible clicks and LED indication
each time a radioactive particle is detected. This feature helps in
real-time detection without the need for additional equipment.
Headphone Usage:
When using headphones with the Geiger Counter, the built-in
speaker is automatically turned off to allow private listening.
Finding Radioactive Sources:
To test for radioactive sources, take the Geiger Counter to
locations known to have radioactive materials such as Coleman
lantern mantles or uranium ore. The counter should emit signals
upon detecting radiation.
FAQ:
Q: How do I know if the Geiger Counter is working
correctly?
A: To test the functionality, you can expose the Geiger Counter
to a known radioactive source and observe if it detects the
radiation. Additionally, ensure the device has sufficient power
supply.
Q: Can I use the Geiger Counter without headphones?
A: Yes, the Geiger Counter provides standard output indication
through clicks and LED flashes even without headphones
connected.
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Images Scientific Instruments Inc. 109 Woods of Arden Road Staten Island NY
10312 718.966.3694 Tel 718.966.3695 Fax www.imagesco.com
Construction Manual and Users Guide Model GCK-01-01
Analog Geiger Counter
Features:
Detects: Alpha, Beta, Gamma and X-Rays. Alpha radiation above 3.0 MeV Beta
radiation above 50 KeV Gamma radiation above 7 Ke
Digital Output — The digital output jack provides a TTL logic high pulse each
time a radioactive particle is detected. The digital output may be interfaced
to a Personal computer (PC) or a microprocessor using our DMAD – Digital Meter
Adapter. Free Windows based radiation monitor and charting programs available.
External Power Jack
Headphone Jack
Standard Output — Geiger Counter clicks and blinks an LED each time a
radioactive particle is detected.
GCK-01-01 Analog Geiger Counter Kit Table of Contents The Geiger
Counter…………………………………3 Radioactivity…………………………………………3 Geiger
Tube………………………………………….4 Count Rate vs. Dose Rate……………………………5 Finding
Radioactive Sources………………………..6 Check Out……………………………………………6 Background
Radiation………………………………6 Separating & Detecting Beta and Gamma…………6
Features………………………………………………7 Schematic…………………………………………….8 Circuit
Construction…………………………………9 Testing the HV Section…………………………….10 Continuing
Construction…………………………..11 Internal Tube……………………………………….12 For External
Wands………………………………..13 Testing before Continuing General Construction..14
Installing/Changing the Battery……………………14 GCK-01-01 Parts List………………………………15
2
The Geiger Counter Geiger Counters are instruments that can detect and measure
radioactivity. H. Geiger and E.W. Muller invented the Geiger counter in 1928.
When you are finished building your Geiger Counter kit you can use it to check
materials and environment for radioactivity. Geiger counters are useful in
performing experiments with radioactivity and nuclear energy. You could even
go prospecting for uranium, if you desire. Radioactivity Radioactivity is the
spontaneous emission of energy from the nucleus of certain elements, most
notably uranium. There are three forms of energy associated with
radioactivity; alpha, beta and gamma radiation. The classifications were
originally made according to the penetrating power of the radiation. Alpha
rays were found to be the nuclei of helium atoms, two protons and two neutrons
bound together. Alpha rays have a net positive charge. Alpha particles have
weak penetrating ability; a couple of inches of air or a few sheets of paper
can effectively block them. Beta rays were found to be electrons, identical to
the electrons found in atoms. Beta rays have a net negative charge. Beta rays
have a greater penetrating power than Alpha rays and can penetrate 3mm of
aluminum. Gamma rays are high-energy photons. This has the greatest
penetrating power being able to pass through several centimeters of lead and
still be detected on the other side. Images Geiger Counter Model GCK-01-01 is
sensitive to all three types of radioactivity.
Geiger Tube The Geiger Mueller (GM) tube hasn’t changed much since it was
3
invented in 1928. The operating principle is the same. A cutaway drawing of
the tube is shown in figure 1. The wall of the GM tube is a thin metal
cylinder (cathode) surrounding a center electrode (anode). It is constructed
with a thin Mica window on the front end. The thin mica window allows the
passage and detection of alpha particles. The tube is evacuated and filled
with Neon, Argon plus Halogen gas. It is interesting to see how the GM tube
detects radioactivity. A 500 -volt potential is applied to the anode (center
electrode) through a ten mega-ohm current limiting resistor. To the cathode of
the tube a 460k ohm resistor is connected.
In the initial state the GM tube has a very high resistance. When a particle
passes through the GM tube, it ionizes the gas molecules in its path. This is
analogous to the vapor trail left in a cloud chamber by a particle. In the GM
tube, the electron liberated from the atom by the radioactive particle and the
positive ionized atom both move rapidly towards the high potential electrodes
of the GM tube. In doing so they collide with and ionize other gas atoms. This
creates a small conduction path allowing a momentary surge of electric current
to pass through the tube.
4
This momentary pulse of current appears as a small voltage pulse across R2.
The halogen gas quenches the ionization and returns the GM tube to its high
resistance state making it ready to detect radioactivity.
Count Rate Vs Dose Rate Each output pulse from the GM tube is a count. The
counts per second give an approximation of the strength of the radiation
field. Below is the approximate GM tube’s response to a cesium-137 source,
shown in figure 2.
Features: GMT Tube The GCK-01-01 features the GMT-01 (LND 712)
5
A more reliable source is to purchase a radioactive source. Small amounts of
radioactive materials are available for sale encased in 1 inch diameter by ¼”
thick plastic disks. The disks are available to the general public license
exempt. This material outputs radiation in the micro-curie range and has been
deemed by the Federal government as safe. The cesium-137 is a good gamma ray
source. The cesium 137 has a half-life of 30 years. Check Out Turn on the
Geiger counter. If you have a radiation source bring the GM tube close to it.
The radiation will cause the Geiger counter to start clicking. The LED will
pulse with each click. Each click represents the detection of one of the
radioactive rays; alpha, beat or gamma. Background Radiation Background
radiation, from natural sources on earth and cosmic rays will cause the Geiger
counter to click. In my corner of the world I have a background radiation that
triggers the counter 12-20 times a minute. Separating & Detecting Beta and
Gamma By placing shields of different materials in front of the GM tube we can
filter out some radiation. For instance placing a paper shield in front of the
GM tube will block all the Alpha radiation. The Geiger counter will now only
detect beta and gamma radiations. If we place a thin metal shield in front of
the GM tube that would effective block the alpha and beta radiation, allowing
the detection of gamma radiation.
6
The Geiger-Mueller tube (GMT-01), is Ne + Halogen filled, with a .38″
effective diameter 1.5-2.0 mg/cm2 mica end window.
Data Output The data output jack may be used for an analog meter. The analog
meter is an accessory that plugs into the data output jack and provides a
visual indication of the approximate radiation level. The data output provides
a TTL logic (+5V) pulse every time the Geiger counter detects radiation. This
signal can easily be connected to a microcontroller or PC. The PC or
microcontroller can then be used to create a digital Geiger counter, chart
recorder or other recording instrument for nuclear experiments.
External Power Jack The GCK-01-01 may be powered by either a 9-Volt battery or
external power source with a 2.5mm jack.
Head Phone Jack When using the headphone jack for headphones the speaker is
automatically cut-off.
Finding Radioactive Sources The mantle in some Coleman lanterns are
radioactive. Bring your Geiger counter to a local hardware store and check
them out. Uranium ore from a mineral or a rock store should also emit
sufficient radiation to trigger the counter.
7
8
R4 should be 1K. R10 is not used.
5A. PCB for GMT-02 & external wand
5B. PCB for LND712 (GMT-01)
Circuit Construction
The schematic for the GCK-01-01 is shown in Figure 4. The top silkscreen of
the PCB is shown in Figure 5.
Before beginning construction, it is important to decide if you will be using
an external wand or attaching the GM tube directly to the PC Board. If you are
attached the GM tube directly to the PCB, we must insulate a section of the
board to prevent it from shorting out. To do this peel the backing from the
included piece of vinyl and wrap and wrap it around the section of the pcb
located above the cutout. Begin on the back of the pcb at the top of the
opening, wrap it around the top of the pcb and back through the opening. This
area is marked with 2 lines on the front of the pcb and shown in black in
Figure 5B.
Begin construction by soldering resistors R17 5.6K (color bands green, blue,
red), R18 4.3K (color bands yellow, orange, red) and R9 15K (color bands
brown, green, orange). Next we will wire the square wave generator and pulse
shaping circuit using the ICS-16 socket for the 4049, marked U4 on PCB. Insert
the ICS-16, making sure to orient the notch on socket to the drawing on the
PCB and solder to the board. Place and solder components C8 (.01uf), C9
(.0047uf), C10, (.1uf) and D10 (1N914). Now construct the high voltage section
consisting
9
of the step up transformer T2, diodes D4 & D5 (1N4007) and capacitors C3, C4
and C5 (.01uf 1KV). Mount IRF830 transistor Q2 to the PCB, bend the transistor
outward so it lays flat on the PCB, see Figure 6, and solder. To this add the
5 volt 7805 regulator (U3), bending it outward so it lays flat as with
transistor and solder into position. Next mount and solder capacitors C6
(220uf-330uf), C7 (22uf), and diode D9
(1N5817). Place and solder the 9-volt battery cap on the PC board. The red
lead connects to the positive terminal P12. The black lead connects to GND,
marked P9. Solder the power switch to the PCB at S2. Insert 4049 into the
socket, making sure to orient the notch on the chip to the notch on the
socket.
Testing HV Section CAUTION: Circuit generates high voltage power that can
provide an electrical shock. Exercise caution when working around the high
voltage section of the circuit. The capacitors C4 and C5 can hold a HV charge
after the circuit has been shut off. To check the HV power supply; turn the
power switch off. Insert the 9 -volt battery onto the battery cap. Set up a
VOM to read 500 to 1000 volts. Place the positive lead of the VOM at P11. The
negative lead of the VOM is connected to the–(negative) terminal of the 9-Volt
battery.
10
Apply power to the circuit using the power switch, The circuit should generate
anywhere between 550 and 800 volts (depending upon component tolerances) If
you are reading between 550 and 800 volts, fine, turn off the power. Add the
three zener diodes; D6 (100V) and D7 & D8 (200V). Attach a 2-pin header at
P10. Apply power again, with the positive lead of the VOM still attached to
P11; you should read a voltage of 500 volts. If you’re not getting a proper
voltage reading, check the zener diodes to make sure you have them orientated
in the right direction.
Continuing Construction
Finish the construction of the circuit by adding the ICS-8 for the 555 timer
and the ICS-14 for the LM339. Again, be sure to align the notch on the socket
and chips with the silkscreen on the PCB. Mount and solder all remaining
resistors; R1 & R4 are 1K resistors (color bands brown, black, red). R2,
R5-R8, R12 & R19 are 10K resistors (color bands brown, black, orange). R3 &
R11 are 1 Meg resistors (color bands brown, black, green). R13 is a 100K
resistor (color bands brown, black, yellow). R15 & R21 are 330 ohm resistors
(color bands orange, orange, brown). R16 is a 10 Meg resistor (color bands
brown, black, blue), and R20 is a 470 ohm resistor (color bands yellow,
purple, brown).
Next mount and solder capacitors C1 & C2 (.1uF), C11 (.047uF) and C12 (.01uf).
Mount and solder the 1 Meg, 25-turn potentiometers (R14) on the underside of
the board.
Now mount and solder the 5.1V zener diode (D2), the Audio switch, power jack,
headphone jack and digital output jack. Mount and solder the speaker,
transistors Q1, Q3 & Q4 (2N3904), 2-pin headers (P2) and LED (the longer of
the LED terminals is positive (+) ) to the PCB. The LED should rise 3/8″ from
the PCB to the bottom of the LED. This distance will insure proper placement
of the LED when the PCB is mounted inside the case.
Mount and solder the bridge rectifier making sure to align the + terminal of
the rectifier to the + terminal on the PCB. At this point your Geiger counter
pc board should look like Figure 7 without the GM tube.
The Geiger Muller tube has two leads. It is mounted on the bottom side of the
PCB. The wire connected to the metal sides of the tube is the negative
terminal. This is soldered to the (-) GM terminal on the
11
PC board. The center terminal of the GM tube has a removable solder lead.
Remove the lead, solder 1.5″ of wire to and. Reattach the lead to the center
terminal of the GM tube. Take the opposite end of the wire and solder to the
(+) GM terminal on the PC board.
Internal Tube The Geiger Mueller tube is delicate and needs to be protected in
an enclosure. However the enclosure has a 1/2″ hole that allows the front
surface (mica window) of the GM tube to remain exposed. This way alpha
particles can pass through the thin mica window and be detected. After
securing with a wire, as in Figure 8, a small amount of glue or epoxy can be
dabbed on the wire tube assembly for added support. Before mounting the PCB
inside the case, check to make sure the entire Geiger Counter circuit
functions. To do this you may use either our Digital Meter Adapter (DMAD-04)
or Analog/Digital Meter (ADM-01). The DMAD-04 plugs into the Digital Output
(J1) of the GCK-01. The ADM-01 is connect to the PCB using the wiring diagram
found in the ADM-01 Manual.
Calibrating your GCK-01-01 Using an ADM-01 or DMAD-04 Meter
12
For External Wands
The anode
resistor for the
GM Tube
is housed
within the wand. R16 should be jumped with a small piece of wire.
Attach and solder the 8-pin min-din connector to the underside of the PCB as shown in Figure 9 below.
Caution: Plugging or unplugging the GM wand (GCW-01) while the Geiger counter is on may damage the circuit. This damage is not covered under warranty. 13
We can use a simple procedure to get an approximate calibration for the
analog/digital meter. The difficulty in calibrating the meter has much to do
with the variables in play. The tube’s response can vary +/- 20 %. The
strength of the radioactive source can also vary in addition to variations in
our electronic components. All these factors affect accuracy. With this being
said, we can proceed to get that approximation for our Geiger counter.
Our calibration procedure uses a 10 uCi CS-137 source. Any radioactive
material (see Finding Radioactive Sources) may be used for this procedure. To
begin hold your radioactive source against the GM tube as close as possible.
You may need to use a rubber band or tape to hold the source in place. Adjust
the potentiometer at R14 until you obtain the highest possible CPS (Counts per
Second) reading on the meter.
Now remove the radioactive source and move it away from the GM tube to the
point that it no longer affects the meter readings. Check background
radiation. Normal background radiation for our facility ranges from 15-35 CPM;
background radiation levels vary from location to location and are dependent
on a variety of factors. A simple internet search of “normal background
radiation levels” with your location will provide you with data specific to
you.
While checking for background radiation, you should also check that the meter
is reading single pulses. If you are getting double pulses the majority of the
time, turn the potentiometer down. If you are consistently getting high
background readings, check that your radioactive source has been placed out of
range and then turn the potentiometer until you have reached acceptable norms.
When you are satisfied that the circuit is working properly, it can now be
mounted in a suitable housing. The following instructions are for mounting
inside Images SI’s Analog Geiger Counter Case.
Mount the PC board to the front of the case. The shafts of the two PC mounted
switch and LED should fit into the pre-drilled holes. The PCB is held to the
case front using the two nuts to the PC mounted switches.
Finish by placing the 9-volt battery cap into the battery compartment of the
back case. Close the case and secure with case screws.
14
Installing /Changing Battery To install or change battery open battery
compartment on the back of the Geiger counter and install or replace battery,
see Figure 10.
15
GCK-01-01 Parts List
(1) PCB-66
D6
1N5271 Diode 100V Zener (1)
(1) GMT-01
D7, D8 1N5281 Diodes 200V Zener (2)
(1) self adhesive black vinyl strip
D9
1N5817 Diode (1)
R1, R4 1K 1/4W Resistor (2)
D10 1N914/1N514 Diode (1)
R2, R5, R6, R7, R8, R12, R19
U1
LM339 (1)
10K 1/4W Resistors (7)
14 pin socket (1)
R9
15K 1/4W Resistor (1)
U2
W01M – Bridge Rectifier (1)
R3, R11 1 Mega Ohm 1/4W Resistor (2) U3
7805 Voltage Regulator (1)
R13 100K 1/4W Resistor (1)
U4
4049 (1)
R15, R21 330 Ohm 1/4W Resistors (2)
16 pin socket (1)
R16 10 Mega Ohm 1/4W Resistor (1) U5
LM555 Timer (1)
R17 5.6K 1/4W Resistor (1)
8 pin socket (1)
R18 4.3K 1/4W Resistor (1)
Q1, Q3, Q4
R20 470 Ohm 1/4W Resistor (1)
2N3904 Transistors (3)
R14 1 Meg 25-Turn Pot. (1)
Q2
IRF830 (1)
C1, C2, C10
J1, J2 Jack-05 Audio Jack (2)
0.1uF 50V Capacitors (3)
P2, P10 2 pin headers (2)
C3, C4, C5
P7
PJ-102B power jack (1)
0.01uf 1KV Capacitors (3)
P8
SPK-05 speaker (1)
C6
220uF 10V Capacitor (1)
S2, S3 SW-07 toggle switches (2)
C7
22uF 50V Capacitor (1)
T2
HVT-03 transformer (1)
C8, C12 0.01uf 12V Capacitors (2)
P9, P12 BAT-01 battery clip (1)
C9
0.0047uf 100V Capacitor (1)
C11 0.047uF Capacitor (1)
Additional parts included for alternate configurations.
D2
1N751 5.1V Zener Diode (1)
D3
Red Subminiature LED (1)
D4, D5 1N4007 Diodes (2) 16
References
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