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Old 17th October 2012, 10:19 PM   #11
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I am getting a pulse out of the transformer with a lot of ringing.
Is there anyway to stop this ?
I think the ringing is interfering with pulsees close together.
http://www.ckp-railways.talktalk.net/00.jpg
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Old 17th October 2012, 10:37 PM   #12
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Is the current limit circuit peak/pulse detect or level detect?
Is the limit pin cap bypassed?
What is your topology?
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Old 17th October 2012, 11:24 PM   #13
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Post your circuit.
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Old 18th October 2012, 12:59 AM   #14
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I have added 180pf and 1k snubber across transformer primary and this has improved the ringing a lot.
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Old 18th October 2012, 01:00 AM   #15
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Quote:
Originally Posted by Yooper View Post
Is the current limit circuit peak/pulse detect or level detect?
Is the limit pin cap bypassed?
What is your topology?
I have a resistor in series with the triac and measure the voltage across it.
The PIC looks at the over current pin.
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Old 18th October 2012, 01:01 AM   #16
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Quote:
Originally Posted by sawreyrw View Post
Post your circuit.
I have used the L6565 example circuit (the first one in the datasheet) and replaced the L6565 with a PIC.
My screenshots dont come out well.
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Old 18th October 2012, 01:27 AM   #17
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Here is the latest waveform.
The low part is the transformer primary charging up.
The high part is the secondary passing current through a diode into a smoothing capacitor.
Then there is a large gap which if I try to put out another pulse I get an over current event. Still needs a bit of thought as to why.
http://www.ckp-railways.talktalk.net/000.jpg
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Old 18th October 2012, 01:37 AM   #18
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That waveform looks good to me.
you should easily be able to double the frequency of pulses with that setup.
Do you have any load connected.?
use bits of paper between the outside legs of the cores, and watch the differences with different gaps. then do the same with different loads.
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Old 18th October 2012, 01:45 AM   #19
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Originally Posted by whizgeek View Post
That waveform looks good to me.
you should easily be able to double the frequency of pulses with that setup.
Do you have any load connected.?
use bits of paper between the outside legs of the cores, and watch the differences with different gaps. then do the same with different loads.
I have a 25R resistor connected.
I am using an etd34 N97 core with 2mm gap.

As soon as I decrease the spacing between pulses I get an over current detect to the PIC.
I read a bit on the L6565 and it waits for transformer current to go to zero before it outputs another pulse. I am just using a timing loop in the software after looking on the scope.
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Old 18th October 2012, 01:47 AM   #20
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post the current waveforms used to detect oc.
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