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Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
coffeetable wrote ...
The materials at hand are a 2SD1555 transistor (built in damper diode, ~5V threshold voltage) and a 12V power supply. And it doesn't work.
That's a HOT, they don't work well in this circuit (probably because of very low Hfe).
You want a transistor similar to 2n3055, with <300V C-E max. voltage, I believe the low voltage ones are made with different process than the high-voltage horizontal output transistors.
EDIT: You can try decreasing the value of the top resistor. The circuit might start oscillating but it will probably work pretty bad with your transistor.
Registered Member #2316
Joined: Tue Aug 25 2009, 03:04AM
Location: Bendigo, Australia
Posts: 107
Dr. Kilovolt wrote ...
spark wrote ...
Can this circuit produce dangerous currents if a small FBT and 12V is used? I really wanna build this circuit but first I want to know how dangerous it is.
No circuit is dangerous if you observe safety precautions (like draw arcs to earthed wire and stay away from the HV output) I think not too dangerous currents are involved, probably below 20mA on the output.
You would be very lucky to get 20 mA out of a flyback. They generaly put out 5 mA(the new ones) and 10 mA(the old ones). However RF burn is very bad. It burns tiny holes into your flesh. I don't want to put you off but be careful around HFHV.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Zeus wrote ...
You would be very lucky to get 20 mA out of a flyback. They generaly put out 5 mA(the new ones) and 10 mA(the old ones). However RF burn is very bad. It burns tiny holes into your flesh. I don't want to put you off but be careful around HFHV.
Where they put out 5mA? In the TV? You forgot that our drivers can push X-times more power through the transformer than it did put out in the TV With the old-style AC ones, I think 50mA is not a problem (based on the appearance/thickness of the arc.)
Remember that if your driver draws e.g. 500W from the wall (most good flybacks can take this for a short time), the transformer can see over 1500VA. And with 20kV on the output, that's maybe something like 75mA short circuit current.
Registered Member #2316
Joined: Tue Aug 25 2009, 03:04AM
Location: Bendigo, Australia
Posts: 107
In regards to old flybacks 50 mA is possible because my hacked CFL circuit can melt glass and salt. However in this circuit 5 to 20 mA is likely. HFHV to my understanding is not as lethal as DC because AC will not lock musles like DC. A CRT needs a electrostatic field so the current only needs to be around 100 micro amps.
Registered Member #2871
Joined: Sat May 22 2010, 06:50PM
Location:
Posts: 81
sorry for reply on an old topic!I made this circuit..I use 500ohm resistor(combination of 3w and 10w resistors),18ohm resistor(combination of 10w resistors),25v 4400uf,250v~0,33uf(gpf type).Also i use this transistor:http://pdf1.alldatasheet.com/datasheet-
pdf/view/12991/PANASONIC/2SC5406A.html and i dont take anything!I used a 7v 3A battery!The problem maybe is the materials or the power supply?
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
aris wrote ...
sorry for reply on an old topic!I made this circuit..I use 500ohm resistor(combination of 3w and 10w resistors),18ohm resistor(combination of 10w resistors),25v 4400uf,250v~0,33uf(gpf type).Also i use this transistor:http://pdf1.alldatasheet.com/datasheet-
pdf/view/12991/PANASONIC/2SC5406A.html and i dont take anything!I used a 7v 3A battery!The problem maybe is the materials or the power supply?
Sorry for my English!
That's a HOT, they don't work well in this circuit (probably because of very low Hfe).
You want a transistor similar to 2n3055, with <300V C-E max. voltage, I believe the low voltage ones are made with different process than the high-voltage horizontal output transistors.
EDIT: You can try decreasing the value of the top resistor. The circuit might start oscillating but it will probably work pretty bad with your transistor.
Registered Member #2871
Joined: Sat May 22 2010, 06:50PM
Location:
Posts: 81
But this transistor work with the original driver..I forgot to mention that i use this diode(BY397P:http://www.datasheetcatalog.org/
datasheet/GeneralSemiconductor/mXusvqx.pdf).Also here are some of my capacitors:
Registered Member #2925
Joined: Sun Jun 13 2010, 06:38PM
Location:
Posts: 4
Hey guys, i need some help with my driver.
1 i use this diode: D31F6 (SIYU) 2 my cap is 3500uF 50V 3 and second Cap is a 0.22uF (The same XG-VF posted here but lower) 4 i use 22R 10W 5 i use a flyback from 15" LG and use 8 turns 18AWG for primary and 3 turns 22AWG for feedback
My 2n3055 toshiba transistor mounted in cooler and keep cooled all time, my pilot lamp burns inside and a metal wire smelts but the sparks only shows at almost short circuiting the cables from flyback and i need to do this to see the sparks with i'm powering with two batteries with 6V and 2.5A in series.
Please help-me i need to know where is the problem, if is my driver or power source or i made some wong substitutions.
Some pics form my driver "working" with this lower performer runing from those battery 12V, 2.5A.
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Hellraiser wrote ...
Hey guys, i need some help with my driver.
1 i use this diode: D31F6 (SIYU) 2 my cap is 3500uF 50V 3 and second Cap is a 0.22uF (The same XG-VF posted here but lower) 4 i use 22R 10W 5 i use a flyback from 15" LG and use 8 turns 18AWG for primary and 3 turns 22AWG for feedback
My 2n3055 toshiba transistor mounted in cooler and keep cooled all time, my pilot lamp burns inside and a metal wire smelts but the sparks only shows at almost short circuiting the cables from flyback and i need to do this to see the sparks with i'm powering with two batteries with 6V and 2.5A in series.
Please help-me i need to know where is the problem, if is my driver or power source or i made some wong substitutions.
Some pics form my driver "working" with this lower performer runing from those battery 12V, 2.5A.
@edit: Another question my 0.22uF capacitor has polarity?
What is the voltage over the batteries when you draw an arc? They could be discharged?
Registered Member #2925
Joined: Sun Jun 13 2010, 06:38PM
Location:
Posts: 4
The driver drains all tension from battery and it shows decresing until 0V but the battery shows 13V disconect and i use it for tests when i built this driver today. You think the battery is insuficient or i built it with wong itens? I token those batteries from newer emergency light about 2 weeks they're in constanting float charger.
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Improved single transistor flyback driver
(like draw arcs to earthed wire and stay away from the HV output) I think not too dangerous currents are involved, probably below 20mA on the output.
