X-Ray Tube Filament Current Source

A vacuum tube filament current source and power distribution board circuit

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While developing an X-Ray source using a dental X-Ray tube, I found that I needed a current supply that could be adjusted remotely and on the fly.

As opposed to a 'traditional' power supply that supplies a voltage and lets components draw as much current as they need, this circuit provides a fixed voltage, but limits the current that components can draw using a power MOSFET and an OP amp. It is controlled with DS3502 digipot using i2c coming from a microcontroller (Arduino, ESP, etc), and will output between 1.5A and 2.5A depending on the position of the potentiometer.

This circuit also features an L7805 to step down the input voltage to 5V for the other parts of the X-Ray source. (ESP-8266, relays, etc)

A short clip of the filament being powered at around 2A:
  • 1 × 100Ω 1/4W Resistor
  • 1 × 1kΩ 1/4W Resistor
  • 1 × 15kΩ 1/4W Resistor
  • 1 × 470kΩ 1/4W Resistor
  • 1 × 100mΩ 1W Resistor

View all 10 components

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