Voltage-Doubler Circuit

D1, D2, C1, and C2 double the AC line in, charging C3 through R1 to approximately 320 volts. R1 isolates the voltage doubler from the discharge capacitor C3 so that C1 and C2 do not participate in the flashtube discharge path. R2 and D3 form a 16-volt supply for a relaxation ocillator from parts R3, R4, R5, R6, C4, and the PUT. This gates the SCR at approximately 60-70 times each minute, which discharges C5 through the primary of the trigger coil, thereby triggering the flashtube. R7 and R8 form a volt age divider to keep the voltage within safe limits for the SCR and C5. The flash energy produces 320 x 320 x .0001 x .5 = 5.12 joules.

CAUTION: Hazardous voltage exists within this circuit that can deliver a substatial shock, as is the case with most circuits that are powered off of a 110-volt line.

• Diodes:
  • D1, D2: 1N4004 or equivalent
  • D3: 16 volt zener diode 1N966B or equivalent

• Capacitors:
  • C1, C2: 4.7 microfarad 240 volts
  • C3: 100 microfarad 450 volts
  • C4: 2.2 microfarad tant. 25 volts
  • C5: .47 microfarad film 250 volts

• Resistors:
  • R1: 500 ohms 20 watts
  • R2, R7: 220K 1 watt
  • R3, R8: 240K .5 watt
  • R4: 47 ohms .5 watt
  • R5: 39K .5 watt
  • R6: 15K .5 watt

• Transistor:
  • PUT: 2N6027

• Silicon Controlled Rectifier:
  • SCR: MCR100-4 or 2N5064

• Trigger Coil: 6KV

• Flashtube: xenon type flashtube