# Help with xenon flash circuit

#### Небојша Илић

Joined May 14, 2017
7
I need help with this circuit. F.T. Capacitor Cs is 330V 800uf, Ct is 400V 0.047uF, resistor is 5.1M, triger coil is TC-36.
In this circuit capacitor Cs discharge through flash tube with full power.
I want to control discharging power in steps of 1/2, 1/4, 1/8 ...
How could this be achieved?

#### bertus

Joined Apr 5, 2008
20,766
Hello,

The ciruit only works when the capacitor is charged with a high voltage.
There are circuits that will charge the capacitor from a battery.

Bertus

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#### Небојша Илић

Joined May 14, 2017
7
O
Hello,

The ciruit only works when the capacitor is charged with a high voltage.
There are circuits that will charge the capacitor from a battery.

Bertus
O.K. Thanks for image, but I know how capacitor is charged, and how flash tube works. I dont know how to reduce/limit capacitor discharge into lamp to produce lower power of flash (1/2,1/4, 1/8...).

Joined Jan 15, 2015
5,646
O

O.K. Thanks for image, but I know how capacitor is charged, and how flash tube works. I dont know how to reduce/limit capacitor discharge into lamp to produce lower power of flash (1/2,1/4, 1/8...).
Which brings us to:
Before a flash fires, it determines how long it should fire to get the necessary exposure. The longer the flash fires, the brighter it will illuminate the subject. Flash Exposure Compensation works a lot like exposure compensation: turn it down one stop and the flash effectively gets darker; turn it up one stop and it gets brighter.
The above quote was taken from here.
So it becomes a matter of controlling the actual flash duration.I could have a bank of for example four capacitors and choose one of four to control my flash duration. Just as an example Full Power = 8,000 uF, 75% Power = 4,000 uF, 50% Power = 2,000 uF and 25% or 1/4 Power = 1,000 uF. I can mechanically switch or I can electronically select .

I can electronically or manually choose the capacitor I want and control the actual flash on time.

Ron

#### Sensacell

Joined Jun 19, 2012
2,598
Commercial flashes control the power level by placing a switch (usually an IGBT) in series with the flash tube.

The flash power is controlled by timing the switch, cutting it off mid discharge for 50%, for example.

#### Небојша Илић

Joined May 14, 2017
7
Commercial flashes control the power level by placing a switch (usually an IGBT) in series with the flash tube.

The flash power is controlled by timing the switch, cutting it off mid discharge for 50%, for example.
I was assuming something like that.
Any idea for circuit wherе to put IGBT or even thyristor?

#### Небојша Илић

Joined May 14, 2017
7
Which brings us to:

The above quote was taken from here.
So it becomes a matter of controlling the actual flash duration.I could have a bank of for example four capacitors and choose one of four to control my flash duration. Just as an example Full Power = 8,000 uF, 75% Power = 4,000 uF, 50% Power = 2,000 uF and 25% or 1/4 Power = 1,000 uF. I can mechanically switch or I can electronically select .
View attachment 127257
I can electronically or manually choose the capacitor I want and control the actual flash on time.
OK, that is one idea I have been considering, but I am more interested in circuit with only one big capacitor. I found on net information that is done by thyristor and series of resistor, but so far I couldnt find a funcional circuit.
Ron
Which brings us to:

The above quote was taken from here.
So it becomes a matter of controlling the actual flash duration.I could have a bank of for example four capacitors and choose one of four to control my flash duration. Just as an example Full Power = 8,000 uF, 75% Power = 4,000 uF, 50% Power = 2,000 uF and 25% or 1/4 Power = 1,000 uF. I can mechanically switch or I can electronically select .
View attachment 127257
I can electronically or manually choose the capacitor I want and control the actual flash on time.

Ron
Commercial flashes control the power level by placing a switch (usually an IGBT) in series with the flash tube.

The flash power is controlled by timing the switch, cutting it off mid discharge for 50%, for example.
Which brings us to:

The above quote was taken from here.
So it becomes a matter of controlling the actual flash duration.I could have a bank of for example four capacitors and choose one of four to control my flash duration. Just as an example Full Power = 8,000 uF, 75% Power = 4,000 uF, 50% Power = 2,000 uF and 25% or 1/4 Power = 1,000 uF. I can mechanically switch or I can electronically select .
View attachment 127257
I can electronically or manually choose the capacitor I want and control the actual flash on time.

Ron

#### Небојша Илић

Joined May 14, 2017
7
Which brings us to:

The above quote was taken from here.
So it becomes a matter of controlling the actual flash duration.I could have a bank of for example four capacitors and choose one of four to control my flash duration. Just as an example Full Power = 8,000 uF, 75% Power = 4,000 uF, 50% Power = 2,000 uF and 25% or 1/4 Power = 1,000 uF. I can mechanically switch or I can electronically select .
View attachment 127257
I can electronically or manually choose the capacitor I want and control the actual flash on time.

Ron
OK, that is one idea I have been considering, but I am more interested in circuit with only one big capacitor. I found on net information that is done by thyristor and series of resistor, but so far I couldnt find a funcional circuit.

Joined Jan 15, 2015
5,646
Using Google I can find block type diagrams but I am also having a problem finding an actual circuit. Anyone have anything?

Ron

#### Небојша Илић

Joined May 14, 2017
7
Using Google I can find block type diagrams but I am also having a problem finding an actual circuit. Anyone have anything?

Ron
Post some of its here. More useful informations, more chances to find solution for this.