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Roentgen X-Ray Generator Diode Vacuum Electron Tube Circuit Electronics 2

OddMix.com - Technology Note - TN1207A - Karl Nagy

Warning! - Higher voltages are dangerous! - Never use both hands at the same time while working on high voltage circuits! - Disconnect power from a circuit when work on it! Think carefully when around high voltages! X-Ray and all ionizing radiation are dangerous! Be extra careful and use shields at all times respect all warnings!

Picture 1. Popular 1G3GT 1B3GT X-Ray Emitter Vacuum Tube [8 KB]
Picture 1. Popular 1G3GT 1B3GT X-Ray Emitter Vacuum Tube

Softer X-Rays are less energetic and their frequency and shielding requirements are lower. Higher voltages yield harder, more energetic and penetrating, higher frequency radiation that can go thru much thicker metal shields. Good shields are made with heavy metals, usually the heavier the better. Lead is an efficient radiation blocker and it is used most often, so is gold and many of the heavy metals. With high energy hard X-Rays a thick layer of lead - or some other metal - shield may be necessary to be completely safe.

Figure 2. X-Ray Generator Tube Circuit Using Automotive Ignition Coil HV Transformer [3 KB]
Figure 2. X-Ray Generator Tube Circuit Using Automotive Ignition Coil HV Transformer

X-ray radiation and the damage it does to live cells is cumulative! Even relatively small radiation exposure doses add up. A smallest amount of radiation exposure from ANY sources is best. The safe amount of X-ray exposure is determined and regulated by many different Government standards in different countries. It is very wise to read, and to pay attention, to all radiation regulations and standards. Do NOT use an X-ray emitter, or do ANY experiments carelessly!

An automobile ignition coil is a transformer that is constructed of a few hundred turns heavier gage primary winding and a few thousand turn fine wire wound around a soft iron core. The whole assembly is encased in a steel enclosure that is outfitted with three connectors. The high voltage [HV] generated in a typical automotive ignition coils is up to 30 kV [kilovolts] or 30,000 Volt, enough to produce a spark about 1-1.5 mm long.

Picture 3. 120 VAC InputGas Igniter HV Transformer Circuit [12 KB]
Picture 3. 120 VAC Input Gas Igniter HV Transformer Circuit

The basic inductive discharge type of ignition system [Kettering System] uses approximately 50 mJ [millijoules] of energy to provide for a dependable ignition of the compressed gas-air mixture in an automobile engine. Using a standard ignition coil along with its condenser and ballast resistor would provide a handy power source for X-Ray generation experiments. There is a need for caution as the open circuit voltage in the ignition coil can be so high that it can destroy the coils insulation unless the energy has a path to flow into. Each pulse of HV energy can be delivered into the vacuum tube connected in a normal or reverse mode and an X-Ray pulse will be generated.

Single HV pulses can be produced with an ignition circuit like shown on Figure 2. with every press of the push button switch. The pulse is generated at the release of the push button NOT at the time of the push! By using an automotive electronic ignition module - or its driver transistors - with an external frequency generator circuit it is possible to make a repetitious train of pulses. The high voltage, few millisecond long pulses are ideal to power the HV vacuum tube where they generate short, intense X-Ray power bursts. A gas igniter HV coil assembly is also a useable component for HV pulse generation. The HV igniter circuit assembly in Figure 3. is used in many gas ranges

The high voltage vacuum tubes used to experiment like an 1B3GT Picture 1. can be operated in the traditional electronic tube configuration using the tubes heated cathode, or they can be employed like the original cold cathode Braun or the improved Crookes type evacuated tube devices were without using the hot cathode to emit electrons. All hot cathode vacuum tubes are cathode emission limited devices thus the maximum amount of electron emission is a function of the cathodes ability to furnish enough electrons for the desired highest current to flow.


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