Charge Pump

Charge Pump

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The motivation for this project comes after watching the video from Ben Eater on his YouTube channel about building a voltage multiplier and having around some SMD components from this box that I wanted to use.

I recommend watching the video since it does a wonderful job explaining how a voltage multiplier works. However, the general block diagram for this project is below.

For the oscillator part of the circuit, I will be using the NE555 timer in A-stable mode and I will be using the reference design from the datasheet on page 11.

I picked the values of R_a, R_b and C to have a frequency of oscillation that varies between 7Hz to 1.44 kHz. No particular preference on this range, these are components that I have available on the SMD assortment kit.

For the charge pump circuitry, I will follow Ben's components values, since I have them available on the SMD assortment kit.

Unfortunately, the SMD assortment kit doesn't have N-Channel transistors. With that, for the inverter, I will use the N-Channel (2N7002k).

Ben used 15 stages and increased the voltage from 9V to around 110V. Let's do some testing and figure it out how many stages should I include in this design.

I built the prototype up to 30 stages, resulting with an output voltage of 280V.

I set the NE555 to oscillate around 768Hz which sets a duty cycle around 76%. No particular preference on the frequency of oscillation for this test.

The design was divided into 2 parts: a main board with a 10-Stage charge pump and an expansion board with a 10-Stage charge pump. The expansion boards can stack on each other to create a bigger output voltage.

Main Board

Schematic (Zoom)

Layout (Zoom)

3D Rendering

Interactive BOM (Link)

Expansion Board

Schematic (Zoom)

Layout (Zoom)

3D Rendering

Interactive BOM (Link)

Main Board + Expansion Boards (Fusion 360)

The boards were manufactured by PCBWay.

Assembled in house.

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