Hello,

I'm looking into making my own strobe light, which I will be running in my car, +12VDC input.

I've been looking at some strobe circuits online trying to figure out how they work. There are quite a few that use a neon bulb connected to the HV transformer, what is this used for?
(like this one here http://www.aaroncake.net/circuits/strobe2.htm
Also, if anyone has a good circuit to use, I'd greatly appreciate it. (The strobe I'm planning on using is here: http://www.goldmine-elec-products.co...tem=1&mitem=13
or this one: http://www.goldmine-elec-products.co...tem=5&mitem=13 )

Thanks,

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Jeff
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A strobe tube needs not only high voltage on the 2 electrodes, but a third capacitive electrode requires a very high voltage pulse (1kV or often much more) to trigger it.

The neon bulb is a spark gap- it's an insulator until a certain voltage is reached, then current flows which either triggers a transformer directly or triggers an SCR driving a transformer. Simple yet effective.

 

But Aaron Cake's circuit has the neon bulb connected directly to the gate, so the gate takes the charged capacitor's current instead of the transformer. Maybe that's why people on his site say the circuit doesn't work! Maybe a resistor in series with the gate would help.
Better circuits use another charged capacitor that dumps into the transformer when the SCR fires. The 1st capacitor is only used for the neon to fire the SCR's gate.

 

The neon triggers the gate of the SCR, which then disharges the capacitor in to the primary of the trigger transformer. The neon itself will turn off once the voltage across it drops by a few volts - removing the gate current.

This is how neon relaxation oscillators work, although in this case the SCR causes the capacitor to be fully discharged each cycle - in a normal neon relaxation oscillator it generates a sawtooth about 10V p-p sat on about 70V or so.

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http://www3.telus.net/chemelec/Proje...obe/Strobe.htm
Here is a 12 Volt Strobe on my Website.

It uses a Strobe tube and has a Good Adjustable Flash Rate.

Take care.............Gary

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Hi Nigel,
Gary's strobe circuit is similar but has a resistor in series with the neon bulb like I suggested so that the transformer gets most of the capacitor's discharging current through the SCR.
An even better strobe circuit has both the neon's current and the SCR's current applied to the trigger transformer like this one:

Attached Thumbnails

 

 

It is also important that the low voltage winding has the correct polarity so that the entire transformer steps-up the voltage instead of the windings opposing. Also that the high voltage wire is positioned near the grounded (negative) terminal of the flash tube since the high voltage pulse is negative when the transformer is wired as shown.