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TCA785 Controlled Rectifier design problems

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z45679420x

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Hey all, I'm trying to design a controlled half wave rectifier using thyristors using the tca785 chip to derive my firing pulses. After wrestling with the UAA2016 for a week I was made aware of the tca785 through this forum. I'm not trying to do anything fancy. I'm aiming for a 30-120V input (3 phase actually, plan to use 3 of these ). I will be supplying the DC supply needed for the logic circuit from an external supply and power consumption is not an issue.

After trying unsuccessfuly to get any pulse from the output using the datasheet test circuits as well as modified example circuits I decided to implement the design posted by user Mr. Cube here except I replaced the 220k Rsync with a 47k resistor. I also had to use 1N914s for the BAY 61s as I did no not have any 1N4148s in stock.

(the one labled 3-triacs)

I've tried it using my intended 2n6400 thyristors as well as btb10 400BW triacs and I'm not getting anything at all. If anything I get the behavior of an uncontrolled rectifier. I just do not see anything coming out of the 785's outputs.

I feel like I'm making a really simple and silly mistake. I am now in a state of desperation. Any help would be appreciated.
 

hi
if u make circuit like in that link
(the one labled 3-triacs)
yes u will never see any pulse in the output off tca785 because he miss to add
c12 at pin 12 that control pulse extention.............
and about pin 13 not conected to vcc but in data sheet for siemens its tied to vcc
for all application...

**broken link removed**
 

See that's what I thought, I will try it again in an hour or so. When I had it configured similar to the datasheet originally I experienced different problems, but I will try it again with your advice and report actual data. Thank you for your reply and I hope that's all the problem is :)
 
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    ycsoh

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By using TCA785,i want to control three phase Scr controlled rectifier...please send the circuit for me,,,i am trying lot for that,,,,

Can u help me.....?

waing 4 ur reply...?

regards
sundar
 
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    ycsoh

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