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Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Need help on this... I cant get the Black text " Danger: High Voltage " to turn white on that red field,it just prints blacktext no matter what i change.
Any help please.. Im using AutoCAD 2007.
I need to spell check before the final proof print.
EDIT: fixed it!
LAbel looks real good, the JPEGification kinda spoils it in this pic though.
Registered Member #3637
Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068
Also, Patrick, could you PLEASE explain to me how you used the half bridge gate drive IC? I have the chip you used, as well as the beefier version FAN7392, (sinks and sources 3 amps) and I can never get them to work properly... Even when following the datasheet!
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Inducktion wrote ...
Also, Patrick, could you PLEASE explain to me how you used the half bridge gate drive IC? I have the chip you used, as well as the beefier version FAN7392, (sinks and sources 3 amps) and I can never get them to work properly... Even when following the datasheet!
You should have spoke up. Its easy to use. first they wont turn on below a certain voltage (UVLO) i think its 9 volts?
ill post a schematic of my own device, BRB in an hour i got to eat.
EDIT: This is the exact circuit i used for my single transistor flyback driver, If you bread board this we can see if it lights up a LED or something. ill talk you through it.
Registered Member #3637
Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068
Patrick wrote ...
Inducktion wrote ...
Also, Patrick, could you PLEASE explain to me how you used the half bridge gate drive IC? I have the chip you used, as well as the beefier version FAN7392, (sinks and sources 3 amps) and I can never get them to work properly... Even when following the datasheet!
You should have spoke up. Its easy to use. first they wont turn on below a certain voltage (UVLO) i think its 9 volts?
ill post a schematic of my own device, BRB in an hour i got to eat.
EDIT: This is the exact circuit i used for my single transistor flyback driver, If you bread board this we can see if it lights up a LED or something. ill talk you through it.
I used 1k pull down resistors on pins 2, 3 and 7.
Oh, right, I forgot you were using to drive only one MOSFET.
I've never been able to get it to work right driving a half bridge, anyway. The high side just never wants to work!
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Inducktion wrote ...
Oh, right, I forgot you were using to drive only one MOSFET.
I've never been able to get it to work right driving a half bridge, anyway. The high side just never wants to work!
We can fix that, whats your schematic look like? both my channels work, if you need the boot strap deal then you may need better components (if the high side doesnt work im suspicous its your boot PS that the problem.) Are you using a push-pull CT, or the half bridge? one is easier then the other.
Lets start a thead in the HV section. label it FAN7382N or something.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Ok mods and fixes complete.
accidental 4 inch arc flash to LV electronics, killed main MOSFET, both TVS's, Bridge rectifier, and my best transformer got smoked.
(Patrick <- depressed)
Ok having topped off the oil, so that 4 inch gap is now oil-not air, replaced and scoped all new semi's. interestingly enough the FAN7382 survived! (i hope it isnt one of the "zombie undead" semi's, that fail a few hours after overvolting.)
Ok the new flyback is installed, this time using the internal primary, meant for 65V, i currently drive it at 78 no load Volts. im sure theres some droop though once current starts getting switched. I should be switching 2 amps average and 4 amps peak throught the primary at about 70 volts.
It arcs every time continuosly across a gap of 1.2 inches and sparks to 1.4 inches intermitenly, in both cases gap electrodes are 0.44 inch dia. ball bearings.
Im thinking the HV out is 37 kV, at maybe 3-4 mA. so about 160 Watts.
Also, for my carbon fiber lifter, ill have to use a main gap of 2.5 or more inches.
EDIT: with no arcs or sparks present, and loaded only with my 10,000:1 Oscope probe (375 Mohm) it reads only 21kV !?
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Ok ive been having problems since the lo voltage side got hit with a 40kV spark.
ive gone through several of my precious STW13NK100Z's MOSFETs, even though before that bad spark i had not had a single mosfet fail. all of them failed the same way 0.01 ohms beteen all three pins, so i believe this indicates overvolting, not overcurrenting.
Until resolved im swithcing over to my cheaper more numerous HGTG7N60A4D IGBTs, this pic shows my new mods...
600 Volt IGBT, with a 300 volt unidirectional TVS from C to E, and an 18 volt bi-directional TVS from G to E... if this blows i dont know what else to try...
Gate drive appears to be way to low, like 3 volts, dont know why though.
I am seriously considering re-engineering the whole dam thing, getting rid of the 555 + FAN7382 and going with the UCC3526N. This will give me better wavform control then the 555, and current control.
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HV Flyback Bench Top Power Supply for Lab.
