moamps

Re: Drip Opto 6 LA2A - Low voltages across the board
« Reply #40 on: November 08, 2018, 04:41:04 PM »
Yay!
So the half-wave rectification was normal all along?

It's full wave rectifier. Please check the frequency of the residual ripple with the scope or write here the time divisions setting.
It's 100 or 120Hz for sure depending of your location.


Re: Drip Opto 6 LA2A - Low voltages across the board
« Reply #41 on: November 08, 2018, 04:50:37 PM »
It's full wave rectifier. Please check the frequency of the residual ripple with the scope or write here the time divisions setting.
It's 100 or 120Hz for sure depending of your location.

Where on the circuit should I get residual ripple? At the fourth filter cap?

moamps

Re: Drip Opto 6 LA2A - Low voltages across the board
« Reply #42 on: November 08, 2018, 05:00:19 PM »
Where on the circuit should I get residual ripple? At the fourth filter cap?

You already measured it on R29 (post 33).

scott2000

Re: Drip Opto 6 LA2A - Low voltages across the board
« Reply #43 on: November 08, 2018, 05:01:00 PM »
It's full wave rectifier.

doh...  :-[ edited

Re: Drip Opto 6 LA2A - Low voltages across the board
« Reply #44 on: November 08, 2018, 08:29:13 PM »
It's full wave rectifier. Please check the frequency of the residual ripple with the scope or write here the time divisions setting.
It's 100 or 120Hz for sure depending of your location.

Time is 2ms/DIV, so I'm measuring a full ripple cycle at 8.2 ms (120 Hz, I'm in Canada).

Where do I go from here? I'm getting the DC I want out of the filter caps BUT, my power supply isn't doing what it's supposed to do.
The original problem is fixed, although there's still something going wrong.

PRR

Re: Drip Opto 6 LA2A - Low voltages across the board
« Reply #45 on: November 09, 2018, 01:26:18 AM »
You have a "bad" rectifier. Check the joints. Replace the tube. Replace the diodes. In that order.

moamps

Re: Drip Opto 6 LA2A - Low voltages across the board
« Reply #46 on: November 09, 2018, 03:17:44 AM »
Where do I go from here? I'm getting the DC I want out of the filter caps BUT, my power supply isn't doing what it's supposed to do.
The original problem is fixed, although there's still something going wrong.

Your power supply works as it should. It's perfectly normal that there is a small ripple at capacitors in the row in an unregulated power supply.  And you can't avoid it. Just move on, and remember what you learned about using a scope.


Re: Drip Opto 6 LA2A - Low voltages across the board
« Reply #47 on: November 09, 2018, 08:39:49 AM »
Your power supply works as it should. It's perfectly normal that there is a small ripple at capacitors in the row in an unregulated power supply.  And you can't avoid it. Just move on, and remember what you learned about using a scope.

Alright. That’s great! You’ve been really helpful and patient moamps... thank you!

But just out of curiosity, why can’t I measure full-wave rectification on the scope?

moamps

Re: Drip Opto 6 LA2A - Low voltages across the board
« Reply #48 on: November 09, 2018, 09:27:11 AM »
But just out of curiosity, why can’t I measure full-wave rectification on the scope?

Of course, you can measure full wave rectification  with a scope. You already did it. :)
But, if your question is why you don't see it on your scope, that's because  you already have the smoothing capacitors connected.

Here is a very nice explanation about  rectifiers.
http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

(direct link doesn't work    go:  electricity and magnetism- dc circuits-power supplies-center tap rectifier)
« Last Edit: November 09, 2018, 09:33:04 AM by moamps »

Re: Drip Opto 6 LA2A - Low voltages across the board
« Reply #49 on: November 09, 2018, 09:40:02 AM »
Of course, you can measure full wave rectification  with a scope. You already did it. :)
But, if your question is why you don't see it on your scope, that's because  you already have the smoothing capacitors connected.

Here is a very nice explanation about  rectifiers.
http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

(direct link doesn't work    go:  electricity and magnetism- dc circuits-power supplies-center tap rectifier)

Actually, my question is: Why am I not seeing this? (see picture attached)


moamps

Re: Drip Opto 6 LA2A - Low voltages across the board
« Reply #50 on: November 09, 2018, 10:19:35 AM »
Actually, my question is: Why am I not seeing this? (see picture attached)

The original reading shows full wave rectifier with partially smoothing capacitor connected thru resistor 2k2W which you shorted in last version. The red waveforms would be 240Hz ripple which can not appear.
If you like to see the full wave rectifier alone, you should omit 2k2w resistor and bridge on it near the rectifier diodes, and then measure the voltage on connection of two diodes (anodes) using your scope.

Re: Drip Opto 6 LA2A - Low voltages across the board
« Reply #51 on: November 09, 2018, 10:28:29 AM »
The original reading shows full wave rectifier with partially smoothing capacitor connected thru resistor 2k2W which you shorted in last version. The red waveforms would be 240Hz ripple which can not appear.
If you like to see the full wave rectifier alone, you should omit 2k2w resistor and bridge on it near the rectifier diodes, and then measure the voltage on connection of two diodes (anodes) using your scope.

Gotcha! Thank you again!


 

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