This HV Module intended for powering Geiger-Muller tubes and building high quality external probe. The module has adjustable HV power supply and tube pulse signal processing circuit for driving long cables. Use this module as an addon for MyGeiger kit or for your own DIY Geiger Counter project.

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
• SKU: RH-K-GK-HV

Why we need this hardware? While using external probe build with DIY Geiger kits you may notice that a standard 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.

The video is demonstration purpose example of external probe build: