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Rollingblackout

Sat Jul 12 2008, 12:12AM

Registered Member #1524 Joined: Sun Jun 08 2008, 05:25PM
Location: Grand Junction, Colorado
Posts: 38

I think I have simply smoked the led in the tlp372 as I connected 15vdc to it as discribed in the book directly to the board connections and not through both r124 and r126. Does that sound about right? R124 and R126 are 25k 5w and I expect the working voltage of the TLP372 led is around 1.5v.

HV Enthusiast

Sun Jul 13 2008, 07:43PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Rollingblackout wrote ...

I think I have simply smoked the led in the tlp372 as I connected 15vdc to it as discribed in the book directly to the board connections and not through both r124 and r126. Does that sound about right? R124 and R126 are 25k 5w and I expect the working voltage of the TLP372 led is around 1.5v.

Yeah, that sounds about right.
Remember, the diode (input) on the optocoupler is a CURRENT device, not a voltage device. It requires a specified current to operate (usually a few mA) If you simply put 15V across it, you'll get a short circuit and blow the diode. You need a limiting resistor.

KresoLiubov

Wed Jul 16 2008, 11:12AM

Registered Member #1153 Joined: Mon Dec 03 2007, 07:27PM
Location: Croatia
Posts: 213

Well i came to my first problem.

All works, except my enable pins are all time pulled down. I apply + 5V to the external modulator input and it is present on PIN 5 of HC14, PIN 9 of HC08 and PIIN 11 of HC74 but it does not propagate to the gate drivers. Any suggestions ?

HV Enthusiast

Wed Jul 16 2008, 04:56PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

KresoLiubov wrote ...

Well i came to my first problem.

All works, except my enable pins are all time pulled down. I apply + 5V to the external modulator input and it is present on PIN 5 of HC14, PIN 9 of HC08 and PIIN 11 of HC74 but it does not propagate to the gate drivers. Any suggestions ?

What is the shutdown pin enable look like?

Also, you may need to have an input drive signal (from primary current feedback) to toggle the flip-flop. I forget since its been awhile since i've looked at the logic. Just do a simple truth table if you have trouble tracing the logic. This will also give you a better understanding on how the synchronized logic operates.

KresoLiubov

Thu Jul 17 2008, 04:29AM

Registered Member #1153 Joined: Mon Dec 03 2007, 07:27PM
Location: Croatia
Posts: 213

I solved the problem. The U21 (LM311) was constantly in "high" over current state. The problem was solved by simply putting a new one in there. I don't know why it was dead (it was new from Digikey). Anyway replaced it and everything works good. All functions of the board work perfectly and i already placed it in the coil.

Thanks for help

Rollingblackout

Thu Jul 17 2008, 06:12AM

Registered Member #1524 Joined: Sun Jun 08 2008, 05:25PM
Location: Grand Junction, Colorado
Posts: 38

Im rethinking my dc power conductors. To go through and do everything in a flat buss. Having not even lit this thing off for the first time, how much peak amperage can I expect between c121,c122 and the half-bridge board, and onto the primary. Will .015 copper 1/4-3/8 wide handle the load with cooling?

I think the "Monster Cable" I have on here now may lead to trouble.
Link

Tom540

Thu Jul 17 2008, 02:41PM

Banned on 3/17/2009.
Registered Member #487 Joined: Sun Jul 09 2006, 01:22AM
Location:
Posts: 617

Monster cable will be fine for powering the bridge but might not be too good for the primary or leading to the primary.

HV Enthusiast

Thu Jul 17 2008, 06:57PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Rollingblackout wrote ...

Im rethinking my dc power conductors. To go through and do everything in a flat buss. Having not even lit this thing off for the first time, how much peak amperage can I expect between c121,c122 and the half-bridge board, and onto the primary. Will .015 copper 1/4-3/8 wide handle the load with cooling?

I think the "Monster Cable" I have on here now may lead to trouble.
Link

Stranded 8 AWG wire is more than enough for both the DC bus and primary connections.

Austin

Thu Jul 17 2008, 07:09PM

Registered Member #1169 Joined: Wed Dec 12 2007, 09:16AM
Location: Portland OR
Posts: 251

yup thats what i used... however u might have some issues finding some good wired to put on MMC where there is no cap.

Ultra7

Thu Jul 17 2008, 10:40PM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

Austin wrote ...

yup thats what i used... however u might have some issues finding some good wired to put on MMC where there is no cap.

I used a paper clip.

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