Ignition coil for flashtubes as HV transformer?

Ignition coil for flashtubes as HV transformer? I want to make a few hundred volts at very low current, a few uA. These trigger tubes for flash tubes seem to do 200V in 4000V out, by discharging a cap in the primary. They are dirt cheap here. So the transformer ratio is 1 : 20. I am thinking about PWMing one to make 500 V peak from 5 V DC. As I do not have one yet, does anybody know the inductance of these things? I used one a hundred years ago in a flash tube trigger circuit... Should have measured it..

Reply to
Jan Panteltje
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An easy source of trigger transformers is disposable cameras - but the transformer is tiny.

Photography shops return the disposable cameras to the factory for recycling and in the UK they get around £50 for a sack full.

Some shops will let you scrounge a few cameras to experiment with, others charge between £0.50p & £1 per camera.

Reply to
Ian Field

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I don't know if this is typical, but:

http://www.rpelectronics.com/90-150-1-trigger-transformer-for-xenon-flash-tube.html
Reply to
John Fields

s?

I measured an old Ford ignition coil a few years ago and the turns ratio seemed to be about 100:1. A 1 volt sinewave gave me about 100 volts out with no load, but I forgot what frequency I was using. I think the primary inductance measured around 10 millihenrys. You get about 2 amps in 2 milliseconds from 12 volts and a 1 ohm primary coil resistance. That's about 5000 RPM and 8 cylinders. Lower RPM is more current and energy.

-Bill

Reply to
Bill Bowden

On a sunny day (Mon, 29 Aug 2011 21:29:13 +0100) it happened "Ian Field" wrote in :

Yea, but I was thinking a bit larger production.

Reply to
Jan Panteltje

On a sunny day (Mon, 29 Aug 2011 22:15:10 -0700 (PDT)) it happened Bill Bowden wrote in :

Those are car ignition coils, I know about those. I was referring to flash tube ignition coils. Those are tiny, 10 mm length, 8 mm diameter. Anyways I found some data, 16.5 turns .25 mm diameter primary,

500 turns .07 mm diameter secondary, 9 kV max secondary without corona or sparks, 4 kV nominal, 200V primary. Looks like I have to order a bunch. Less than an Euro in quantity.
Reply to
Jan Panteltje

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1.69 EUR in 10's. Looks like they're obsolescent.

Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

Probably SMD mount versions now.

Reply to
SoothSayer

On a sunny day (Tue, 30 Aug 2011 05:15:14 -0400) it happened Spehro Pefhany wrote in :

Right, these have a bit higher turns ratio it seems.

I can get other ones from

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for 1.33 Euro a piece, less for per 10, even less for per hunderd.
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Type item number 542144 in their search window for prices, and they ship free above 25 Euro. For > 1000 directly to source probably 25 cents? I tried to find some diodes on mouser.com last night... and gave up. Could not get their 'filter' to work in my browser, digikey worked OK.

BTW do you know if PIC 18F14K22 will be continued for long time?

Reply to
Jan Panteltje

even less for per hunderd.

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above 25 Euro.

No idea, but generally Microchip seldom obsoletes parts and when they do there's usually a direct replacement. What's the difference between the 18F14K22 and 18F14K22T? The latter seems slightly cheaper.

Best regards, Spehro Pefhany

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"it's the network..."                          "The Journey is the reward"
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Reply to
Spehro Pefhany

You didn't make that clear in your post - you suggested along the lines that you needed samples to measure.

Reply to
Ian Field

On a sunny day (Tue, 30 Aug 2011 14:14:54 +0100) it happened "Ian Field" wrote in : tography shops return the disposable cameras to the factory for

Just wanted to know the inductance so I can work out the cicuit, or if somebody used those as HV transformer. Looks like I will order some and run some tests.

Reply to
Jan Panteltje

On a sunny day (Tue, 30 Aug 2011 08:34:24 -0400) it happened Spehro Pefhany wrote in :

Yea, I am porting something from the 16F690 to this, I do not need the high clock speed, but the programming is easier, need to add some stuff that needs a lot of FLASH memory. The paged memory in the 16F690 is a problem for this.

No idea, my (old) datasheet does not know the 'T' suffix. Maybe a mask revision and they finally fixed SPI? But I do not need SPI in this project. Indeed Microchip so far is safer to use, they keep making the chips.

Reply to
Jan Panteltje

owden

ing=3D

Yes, I guess that was an overkill. Maybe something like used in digital cameras for the flash would work? That would be much smaller. I wonder what the inductance is for the tiny flash transformers operating on a couple AA batteries?

-Bill

Reply to
Bill Bowden

All those i have seen have no core (air) and so energy storage is very small and "power" capability is near zero.

Reply to
Robert Baer

On a sunny day (Wed, 31 Aug 2011 00:07:51 -0700) it happened Robert Baer wrote in :

The one Sphero showed a link to has a core: Core: ferrite core E5 R 5.8x15.8mm

Reply to
Jan Panteltje

That would make it usable.

Reply to
Robert Baer

On a sunny day (Sat, 03 Sep 2011 09:34:14 -0700) it happened Robert Baer wrote in :

I only need a few uA.

Reply to
Jan Panteltje

Robert Baer wrote in news:-ZOdnUddT5GJyv_TnZ2dnUVZ snipped-for-privacy@posted.localnet:

I belive that since it does take some power to "light up" a photoflash tube,the inverter XFMR would have some "power capability".

Not so the trigger pulse transformer/coil. all that needs is to establish an electrostatic field to ionize the flashtube's gas to the point of conductivity.

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Jim Yanik
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Reply to
Jim Yanik

Jan Panteltje Inscribed thus:

Grab a disposable camera from a D&P store ! If your nice they may give you a few. :-)

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Best Regards:
                          Baron.
Reply to
Baron

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