Making car amplifier SMPS with tl494 + DC Protection

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#222
i maked smps from first page of this topic. but there is some problems that i hope help me anybody
can do it!

my smps working god without main toroid core with 80mA power dissipation.
i watched gate wave form with osc and every thing is ok and freq is
50kKHz
after adding the main core when i connect smps to battry my 6A fuse
is blown after half of a second.
i think the problem is in winding toroidal core
i did it like below:
4+4 winds for primary with 8 (040 wires)
12+12 winds for secondary with 4 (040 wires)
first i wound primary in all surface of toroid core then secondary
and something else:
my mosfets is irf540
what is wrong with my smps?
 
#223
Hi

I would not use battery as source. Try using supply instead for testing at beginning. I think the only problem you have is with battery that is pretty much unlimited source (amps) and because there is big capacitance on primary side, there goes a lot of amps through fuse.But that is only if you connect whole smps to battery and caps are not charged.
 
#224
thanks for your answer
but i know that the problem is not power source and fuse
let me to explain a little more

when i connect the power source from my 1.5A transformer(12V)
smps consumes about 1.5A and core begins to make buzz!
when i connect it to battery,in one second started to make buzz and
got louder until fuse burned.
i will send pics 4 hours later
and now i'm going to change my core to a ETD one!
best regards
amir
 
#225
The core isn't the proble now, it could any number of things.How did you wind your trafo(not number of turns)?

Sound to me that you output has short.When you start it duty cycle gets bigger = SMPS draws more current

I did the same project and it needs 50-100mA if nothing is connected and 0.5A if LM3886 amp is connected.
 
#226
excuse me
i had problems to connect

this is my smps picture
An externally hosted image should be here but it was not working when we last tested it.

i think the main problem is inductance,because when i connect
transformer in stand by it consumes about 1.5A with AC/DC adapter
but when i remove the transformer consumes about 80mA
it means that magnetic inductance level is low or core's maner like a short circuite.
when i measure output voltage of smps i found that one output is
constant and about 20V and another output increases slowly from
20V to 55V.when i disconnected the input to prevent caps crash!!.
this is my core pic:
An externally hosted image should be here but it was not working when we last tested it.


sellers are saying that this is a perfect ferrite core for about 400watts.
what do you think about that??
and finally
when i replaced the toroid core with an EOI type core
results were worst with louder noise from core!
what can i do now??
thanks for your good helps
bye
 
#227
ESP SMPS design

Hello Guys

I build the Ron Elliot SMPS design and it´s work great.
Also, I build a Nashville NA 2200 power amp replica (originally work with +65/-65V power supply) and it´s supplied by the SMPS with +36/-36V, but, I wind a new toroid to work with +55/-55V to substitute the other. My SMPS use 12 FQP50N06 and BC547/557 drivers. Only 4 2200uF capacitors in the output, no chokes, and no "huumms" or " bzzzz", Ok!! Ahh! No load, the current is 100 mA. I Canupload pictures of the SMPS for you.
Thank you very much
Sandro from Brazil.
 
#231
Ok this works now
First of all I would put one layer of isolating tape on whole core just to prevent any damage to wires isolation.Then put 5 turns for both primarys like so: 5 then center tape then 5 in same direction!!!. Use about let say 15 of 0.5 to 0.8 mm wire in parallel.For secendays put 20 turns center tape and another 20 in same direction. Use up to 6 of 0.5 to 0.8mm (same wire as before) in parallel. Use more wires in parallel if wire is tinner.

I think that is all you need to know, if I didn't forget something.

PS:and twist all wires together before you put them on core, this will make your life easyer.
 
#234
I used original shema and PCB of risto80. I will use it in car to drive single LM3886 with +/-30v with 4 omh sub."I will" by that I only mean that I need a car 🙂 to do that, but the amp is up and running.

Well max power... I don't know, didn't use/test it with anything but amp, but with it, it can produce 100 and some more watts with no problem, the only problem is with the amp, driving that load with sinus at max power 😀
 
#239
i'm back with better results! !
i wound toroid core again in addition to your post but no change in
result.
i tried to change the core with an EOI type core i got from an old
computer power supply i have had in home, now read the results below:

1st: output voltage of both rails are 30.9V
2nd: quiescent current is 83mA
3rd: no buzz!! no humm!! and no other sounds

now the problem:
i decided to exam it with a car light bulb(24V)
when connected it to negative output just a spark while connecting.
when connected it to positive output bulb flashed and turned off.
after spark or flash , smps started to make buzz! but when i disconnected the wires it stop making buzz.
i think if i wind wires tighter and secondary first then primary buzz problem will solve.
but i dont now what is the power transfering problem.
i dont know turns of EOI core but output voltage is correct.
i think it's turns equal with 4 for primary and 12 for secondary.
what do you think about that?
 
#240
First of all don't put load only on one side at a time.This is not amp that draws current from both rails at the same time.Test is with both rail used. 4 for primary is good, but 12 for sec is too low as supply will fast become unregulated (D.C = 50%), voltage will drop.Wires should be tight at all time.
 
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