15kV High-Voltage Diode Stick Prototype
Prototype of a high-voltage diode stick for approximately 15 kV, using no more than 9 series diodes.
Intermediate Project
— The circuit itself is simple, but 15 kV prototype work requires careful attention to insulation, creepage/clearance, surge rating, and safe measurement practices.
Assumptions:
- The user wants a series diode string (not a complete HV supply or multiplier).
- The diode stick is for prototype use only, so ease of sourcing and assembly matter more than production packaging.
- The actual current is likely low, but the reverse voltage requirement is the key constraint.
- Because the requested voltage is 15 kV, none of the verified DB Schottky parts are suitable as the main HV diodes.
Bill of Materials
Compatibility Notes
- The recommended 1N4007 string is a passive HV component and does not interface electrically with the MCU except through any optional measurement or control circuitry.
- If you add sensing or switching around the HV stick, keep the low-voltage MCU side isolated from the HV node and use proper creepage/clearance.
- The Pico runs at 3.3 V logic, so any external measurement front-end must be designed for 3.3 V GPIO/ADC levels.
- Do not use the DB Schottky parts in the provided database for the 15 kV string; their reverse-voltage ratings are far too low for this application.
You'll Also Need
- High-voltage resistors for voltage sharing or bleeder functions, if needed.
- Insulating standoffs, HV-rated PCB material or perfboard spacing, and enclosure.
- HV wire, solder lugs, heat-shrink, and strain relief.
- Measurement probe or divider network if you need to verify the 15 kV output safely.
- No complete HV source or multiplier is included; this list only covers the diode stick itself and optional low-voltage control.
Estimated BOM Cost: $5-20 for the diode stick itself, or $15-35 includ (based on live distributor pricing)
Design Considerations
Voltage Margin
For a 15 kV stick with no more than 9 diodes, the per-diode reverse rating needs to be around 1.7 kV minimum, and more is better for transients. A 1N4007 string gives 9 kV nominal reverse rating if you count 1 kV per diode, so in practice you should verify the actual waveform and consider extra margin if the circuit is pulsed or resonant. If the application has fast edges, reverse recovery and dynamic sharing become more important than the DC rating alone.
Creepage and Clearance
At 15 kV, physical spacing is often the limiting factor, not the diode silicon. Use generous spacing between nodes, avoid sharp solder points, and keep the assembly clean and dry because contamination can create surface leakage and corona. For a prototype, point-to-point wiring with heat-shrink and standoffs is often safer than a tightly packed PCB.
Current and Thermal Stress
Even though the voltage is high, the average current may be low, which is why a simple diode string can work. However, surge current during charging or discharge can be much higher than the steady-state current, so choose diodes with adequate surge capability and avoid relying on tiny signal diodes. If the stick is part of a multiplier or pulsed supply, thermal and repetitive surge limits matter more than average current.
Measurement Safety
Do not probe 15 kV directly with a standard DMM or scope input. Use a properly rated HV probe or a resistor divider designed for the voltage and power dissipation, and place the divider physically close to the measurement point to reduce stray pickup. Add a bleeder path so the assembly discharges after power-off.
Prototype Assembly
Through-hole diodes like 1N4007 are easier to assemble and inspect than SMD parts for this voltage class. Keep lead lengths consistent if you want more even voltage sharing, and mechanically support the string so vibration does not crack solder joints. For a first prototype, a straight axial chain with heat-shrink over each junction is a practical starting point.
Want to customize this project or build something different?
Try the Project Advisor
