Author Topic: Discrete Regulated power supply  (Read 3746 times)

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Offline blackdog

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Re: Discrete Regulated power supply
« Reply #50 on: July 13, 2018, 05:23:33 pm »
Hi Cliff Matthews,

I am currently busy with the work and administration involved.
Some measurements have already been made and of course it generates.  :-DD
But not at a frequency you would expect.

The power supply is easy to set up and to load with 1 or 2 Ampere, so that works.

But debugging takes a lot of time, and I don't have that available now, probably next week.
A bit of patience please  :)

Kind regards,
Bram
Sometimes people don't want to hear the truth because they don't want their illusions destroyed
- Friedrich Nietzsche -
 
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Offline schmitt trigger

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Re: Discrete Regulated power supply
« Reply #51 on: July 13, 2018, 11:29:31 pm »
Blackdog;
I really like your prototype assembly techniques. They show you took the time to lay out things properly.

I specially like your "copper clad chassis". Very ingenious! And it makes a good ground plane too.
 

Offline GigaJoe

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Re: Discrete Regulated power supply
« Reply #52 on: July 15, 2018, 03:34:12 am »
So what the goal ? mediocrity PSU on 2 transistors ?  I may sound sarcastic , but really it not 80x  when find some opamp like to find a precious gemstone
for a zener need const curr, and diff amp need  const curr as well - to minimize pulsation
 

Offline blackdog

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Re: Discrete Regulated power supply
« Reply #53 on: July 15, 2018, 04:06:41 am »
Hi GigaJoe,  :)

I have already explained in this topic that with two opamps you can make a much better power supply.
But also that I like to work occasionally with discrete's, just for fun.

And not to forget, I am still learning from it!

I've already placed some extra "stopping" resistors here and there to avoid oscillations.
At a certain load and output voltage, oscillation occurs around 45 MHz!  :-DD
Touching the collector who is grounded from the differential amplifier, changed the frequency and level, total length of this wire 1.5cm!
Welcome in the world of small fast modern transistors...

A good reason to not do it this way  :)

Some pictures
Testing with a Heatkit dummy load.


The red circels are ground wires, all change the oscillation frequency.
Blue circle, wextra power decoupling off the board, can be removed again.
Small pink circle, collector is now connected via en small 100 Ohm resistor to ground.


Later more.

Kind regards,
Bram


Sometimes people don't want to hear the truth because they don't want their illusions destroyed
- Friedrich Nietzsche -
 

Offline GigaJoe

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Re: Discrete Regulated power supply
« Reply #54 on: July 15, 2018, 05:12:50 am »
OK, got it, even pay attention on circuit, that i missed ...
does osculation happens when current limiter involved ?  That usually a problem with all compensating VR, current pushing regulated signal down, when in the same time a second half trying to compensate it ... that when oscillation happens.
so need to change signal on input of diff ampl.


 
 

Offline GigaJoe

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Re: Discrete Regulated power supply
« Reply #55 on: July 15, 2018, 05:50:23 am »
silly ideas:  dif amp - darlington,   output from a zener going to another zener - that would be a vref;
 


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