Flyback driver not functioning?

ok, after seeing a few threads showing member's home built TEA nitrogen lasers I decided to make one myself. i have half finished the actual laser but have no way of charging it. I couldn't find any laser printers to dismantle to steal its HV module but had plenty of tv flybacks. a couple of yeas ago i built a simple flyback driver out of a 2n3055 some visitors and drive an old B&W tv flyback so that i could make a simple plasma globe.

now i am attempting to drive a newer style colour tv flyback and this is the website I have gotten the driver from: The Professor's Homebuilt Lasers Site - Notes on High Voltage. I have uploaded exactly how mine is set up down below. I have assembled it all. Not just a botch job, on pcb and all however it wont run.

what voltages should i be getting and where?

ANY help will be appreciated. thanks

@ 19v your looking at something in the order of 2.5kV

Do you have the correct pin out for your flyback? Are you sure you have the right polarity on the primary? What frequency are you hitting it with? FBT usually like running close to 22kHz.

Without being connected to the flyback I get 0.4v across the output. Cant test frequency, and when i said what voltages i was meaning what voltages on the driver. As of now the output voltage of the flyback isn't my concern. Im pretty sure i have narrowed it down to the 2n3055 being dead, yes it was well heatsinked. I tested all resistors, the pot and also the 2n3906. the reason being is that it is the only component i couldn't get a good test done on and that i didnt replace, also it was one i had from a while back, ill get a new one when i can and post if it was the problem.

Also I would imagine a higher output on the flyback at 19v... the last one I didnt I got about 15kv and that was off the same supply. Even then I thought that these ran on 12v most of the time in the tv itself. anyway before i worry about that i should get the driver going.

Thanks Bob btw

No probs. Oh I was assuming you meant the flat pack type FBT. Do you have the newer 15 pin FBT with focusing knobs? If so, you should be able to reach about 25kV at ~24v but only with a ZVS driver. I would assume it to be about 15-20kV with a less efficient driver.

Good luck... Without pics of your actual setup its hard to tell.

BTW a ghetto way of testing frequency is put a speaker on the output of the driver and hook up a microphone to the audio jack input on your pc. Now just record a section of the sound and analyze it with a playback program. It will be quite inaccurate, but it will give you a ball park figure which can be handy.

BTW a ghetto way of testing frequency is put a speaker on the output of the driver and hook up a microphone to the audio jack input on your pc. Now just record a section of the sound and analyze it with a playback program. It will be quite inaccurate, but it will give you a ball park figure which can be handy.

Click to expand...

HAHA genius! I will be sure to do that. Im actually not looking for too high of a voltage anyway i dont want to punch through my thin plastic dielectric lol. Its only a small laser.

i would supply pics of my setup but it would kinda be pointless as there inst much to see on it its basically what you see up there except with wires all over the back of the 555. I didnt change the setup much from the schematic so it would be harder to confuse myself .

I would start by reading the Absolute Maximum Specs
on the NE555.....

http://www.fairchildsemi.com/ds/LM/LM555.pdf


According to your Drawing and info... You are inputting
19 VDC into a device that has a ABSOLUTE MAXIMUM
Input Voltage rating of 16 VDC

I would use the Speaker trick at pin 3 of the NE555
first....:undecided:


Jerry

The data sheet provided by the supplier stated 18v as the max and it's not like this thing is going to be used for over 2 mins at a time. Thanks for the tip about pin 3 I will give it a go tomorrow.

Will a microphone even pick up 22KHz? What if its higher?

I still wouldn't plug that chip into a 19V source, 18V or 16V max. Why even risk a possible failure because you're running out of spec? It isn't hard to just wire up some rectifier diodes to the power to drop the voltage to usable levels.