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High Voltage Geiger Probe Driver Power Supply Module 380V-550V with TTL Digitized Pulse Output

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Quick Overview

Adjustable High Voltage Power Supply Module with TTL output.

With a standard construction of wired GM probe, where high voltage transferred over a cable, you get the HV performance drop and tube signal attenuation when counting rate is increasing over 30000 CPM. Despite the standard GM probe construction, the "RH High Voltage Probe Driver" uses different method of signal path and allows you to drive very long probe cables up to several meters without reducing CPM counting results and without HV drop. Maximum probe cable length now depends mostly on the cable quality. The probe was tested and guaranteed to work with high grade low noise microphone cable of 5 meters.

Of course, the module can be used not only for building external probes, but also for a simple radiation detectors or different microcontroller based projects where you need stable and power efficient high voltage power source to drive GM tube.

Technical specifications:

  • Adjustable High Voltage Output 420V-550V (350V-500V version available by request)

  • Compatible with many popular GM Tubes

  • 2.5uS - 5.0uS TTL output of GM pulses

  • Ability to drive long probe cable

  • Input supply voltage 3.0V-4.5V

  • Output current 100uA max. at 550V

  • Includes 4.7M load resistor on the PCB

  • Compatible with PIC / AVR / MSP / Arduino

  • Compatible with MyGeiger ver.2 DIY Geiger Kit

  • Physical dimensions: diameter of the PCB is 53mm (LND-7317 size)

  • Shipping Weight: 150gr

  • UPC Number: 635292807381


High Voltage Geiger Probe Driver Power Supply Module 380V-550V with TTL Output

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  • High Voltage Geiger Probe Driver Power Supply Module 380V-550V with TTL Output



Why we need this hardware? While using external probe build with DIY Geiger kits you may notice that a standard classic DIY probe construction feed the tube with high voltage transferred over the cable. High voltage and signal path line becomes a very long conductor with parasitic capacitance and inductance that reduce HV performance and add signal attenuation at high speed counts. Moreover, excess parasitic capacitance on the tube anode is discharged through it and reduce tube lifetime. Because Geiger tube signals are very short and weak, and when the cable length is increased over one meter, you will notice that the counter starts read less CPM that you can get if you were connecting same tube with shorter wires. No difference on background radiation count, but significant problem if you start test your probe over 30K CPM samples.

"RH High Voltage Probe Driver" has output pin with GM tube buffered TTL signal that can be transferred over long probe cable. The module has HV generated locally and it uses low VDD DC voltage input. An audio cable with Left+Right and GND conductors can be used to connect the probe PCB to your Geiger Counter project. L+R uses for VDD and TTL signal when GND have to be shield conductor of the cable. 

Here is scope screenshots of tube signal after it crossed over 3 meters of audio cable:

  TTL Signal Shape after 3 meters of cable  TTL Signal Shape after 3 meters of cable

HV converter of the module is very efficient on background. With background ambient radiation the current drawn is 200uA (0.20mA) at 450V settings and 300uA(0.30mA) at 520V settings. The maximum output current at 550V is 100uA. The input current depend on radiation or resistive load you apply to HV output, download user manual PDF to see the graphs. The converter works fine with multimeter load, so you can measure the high voltage output directly with regular 10M multimeter at TP pad on the PCB.

Pinout of the RH HV module

The module is compatible with almost every 400V or 500V type Geiger tubes. The round shape of PCB allows you to glue it directly on the pancake LND-7317 metal back-side. The user manual PDF has example photos of the probe construction with LND tube and Atomic.Dave installation kit enclosure.


DOWNLOAD Cover for SI8-B in G366 enclosure design from thingiverse.com

Compatible GM Tubes List: LND-7312, LND-7313, LND-7314, LND-7317, Beta-1, Beta-2, SI-8B, LND-712, SBM-20, SBM-19, SBT-11, SI-29BG, SBT-9, SI-180G, M4011, Philips-18504. Trim the potentiometer and check high voltage on HV TEST POINT. The tube anode is soldered with short wire to TUBE ANODE(+) pad. Load resistor is already included on the PCB.

MyGeiger ver.2 external probe wiring:

The module is fully compatible with MyGeiger kit. VDD supplied from the MyGeiger VDD line. 10uF capacitor must be soldered directly to XLR female socket. There is 2 options how you can wire the signal line to MyGeiger circuit, depend if you’ll use or not the internal SBM-20 tube. The first method without 1K resistor applicable if you not install internal SBM-20 tube. Then you can solder signal wire to the empty cathode tube clip. I would also recommend to remove the 150pF capacitor in this case. The second method with 1K resistor soldered to 2N3904 base. Use it if you still want the internal tube installed and want to connect the external probe sometimes. Solder the 1K resistor as close as possible to transistor base, the ideal location is right over 1K-2.2K junction on the pcb. Click on the diagram to zoom.

MyGeiger ver.2 wiring of external probe with cable

PIC / AVR / MSP / Arduino wiring the probe:

The HV module can be compatible with your own microcontroller project. TTL signal have to be connected to counting pin of the MCU, see example diagram. The first circuit is with NPN inverter and the second is direct wiring to INT pin.

Connecting the HV module TTL output to microcontroller

Simple Radiation Detector build with HV Module:

The HV Module PCB can be used not only for building external probes. You may have already guessed that it also can be used for building a simple radiation detector.

1. By adding monostable multivibrator circuit you can connect led and buzzer output. The one shot multivibrator circuit can be soldered on small veroboard. The multivibrator circuit is less sensitive to layout quality so it excellent for beginner skills.

Simple Radiation Detector with RH HV Module

2. The second circuit diagram is even simpler. It require just several components to solder the very basic detector: neon bulb, 5M resisitor and piezo disc. Take note, the HV connection is made to HV TEST POINT!

Check how this simple circuit is working in youtube video here: https://www.youtube.com/watch?v=I4KlEbfupEQ

Simplest Radiation Detector circuit diagram

Cables and Plugs for the external probe construction:

For the external probe construction use XLR 3 pin sockets. These connectors are strongly recommended. Despite the standart stereo plug, the XLR prevent shorting VDD or GND lines during socket connection.

Cable quality selection depends on desired cable length. For probes with length over 3 meters we recommend to use Low Noise High Grade Microphone Cable. A good high performance audio cable usually has about 0.5 ohm DC resistance for 1 meter of conductor.

If the probe cable length is less than 3 meters than almost any good quality stereo cable will fit. Here is the video with example construction of the probe and 5 meter of cable:

Take note, the purchase includes only HV Module without any cable or enclosure! This is not a kit, the module sold soldered. The module do not have reverse polarity protection! Please put attention how you connect the battery. We do not accept any claims caused by wrong polarity connection! However, the product has technical warranty and we can repair your unit if something fail during 6 months of usage.

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