Hello all,
I have started building the valveaudio car power amp almost similar to the ESP P89 (JUST the power section)
I have completed the PSU section when i power it up .. nothing happens i get 5.5v on the PIN 13 and 15 the data sheet of 3525 says 8~35v. I connect the 12vdc directly to the pin 13 & 15 and the output volt jumps to +/- 29volt .
But within seconds the toroid secondary ground wires become red hot and they start glowing .. i mean glowing like a light bulb
Toriod details
Material = Ferrite core (Looks like a ring magnet)
OD = 46mm
ID = 44.2 mm
THK = 10 mm
Primary winding done first with 0.8mm wire
5 wire x 4 turns tap then 4 again
Secondary winding done with 0.8 mm wire
2 wire x 17 turns tap then 17 again
What should be the voltage on PIN 13 and 15 of 3525 ?
What am i doing wrong...?
BTW nothing blew and nothing got warm except the glow from the toroid wires.
MOSFET Z44n
Diode BYW29
Please help
Thanx
Mastero
PS: I have read almost every thing the search gave me with 3525
I have started building the valveaudio car power amp almost similar to the ESP P89 (JUST the power section)
I have completed the PSU section when i power it up .. nothing happens i get 5.5v on the PIN 13 and 15 the data sheet of 3525 says 8~35v. I connect the 12vdc directly to the pin 13 & 15 and the output volt jumps to +/- 29volt .
But within seconds the toroid secondary ground wires become red hot and they start glowing .. i mean glowing like a light bulb
Toriod details
Material = Ferrite core (Looks like a ring magnet)
OD = 46mm
ID = 44.2 mm
THK = 10 mm
Primary winding done first with 0.8mm wire
5 wire x 4 turns tap then 4 again
Secondary winding done with 0.8 mm wire
2 wire x 17 turns tap then 17 again
What should be the voltage on PIN 13 and 15 of 3525 ?
What am i doing wrong...?
BTW nothing blew and nothing got warm except the glow from the toroid wires.
MOSFET Z44n
Diode BYW29
Please help
Thanx
Mastero
PS: I have read almost every thing the search gave me with 3525
No output with Vcc = 5.5 V is not surprising since the 3525 has an undervoltage lock-out feature requiring Vcc > 8V.
Wrt. the glowing wires - did you check for inadvertent shorts, such as ground loops through meters, o'scopes etc.? Any shorts in the output windings themselves (wire-to-wire, bad insulation)?
--WD
Wrt. the glowing wires - did you check for inadvertent shorts, such as ground loops through meters, o'scopes etc.? Any shorts in the output windings themselves (wire-to-wire, bad insulation)?
--WD
N channel you can down load expresspcb for free from www.expresspcb.com
Good software easy to use..
It was a faulty transistor ... not give 12v to pin 13 and 15.. small things make big difference
15 downloads and no comments
Cheers
Mastero
Good software easy to use..
It was a faulty transistor ... not give 12v to pin 13 and 15..
small things make big difference15 downloads and no comments
Cheers
Mastero
Nice Board
Mastero,
Download was easy. Board looks good. Couple o' questions:
1) Why put the output inductors after the filter caps? Wouldn't it be better to put them before the caps, and perhaps couple them onto the same core? Just an idea I stole from looking inside every AT & ATX box I could get my hands on.
2) What is the pinout for the BYW29? Since I don't know, please forgive me if I'm talking out of school, but it looks like one leg of the secondaries is jumpered directly to the (+) output bus, and the (-) side of one of the BYW29s is tied to the other AC leg of the secondary. Since I do not have the datasheet for this diode, I could be wrong. Is this diode similar to the MUR1520 diode?
3) Have you considered using high-voltage Schottkys? I have used some MBR10100s (10A, 100PIV) with great success, and their forward voltage drop at full load is only 0.65 - 0.7V.
Please give us your thoughts. Thanks a bunch for giving me another project idea!
BTW, did you ever publish your DC-DC ATX schematic from the MP3car.com forum?
Steve
Mastero,
Download was easy. Board looks good. Couple o' questions:
1) Why put the output inductors after the filter caps? Wouldn't it be better to put them before the caps, and perhaps couple them onto the same core? Just an idea I stole from looking inside every AT & ATX box I could get my hands on.
2) What is the pinout for the BYW29? Since I don't know, please forgive me if I'm talking out of school, but it looks like one leg of the secondaries is jumpered directly to the (+) output bus, and the (-) side of one of the BYW29s is tied to the other AC leg of the secondary. Since I do not have the datasheet for this diode, I could be wrong. Is this diode similar to the MUR1520 diode?
3) Have you considered using high-voltage Schottkys? I have used some MBR10100s (10A, 100PIV) with great success, and their forward voltage drop at full load is only 0.65 - 0.7V.
Please give us your thoughts. Thanks a bunch for giving me another project idea!
BTW, did you ever publish your DC-DC ATX schematic from the MP3car.com forum?
Steve
PM650:
next time u're making a board , make sure to make the power lines first , then connect the low current signals using those "jumpers" if needed .
i also think that the caps should be aftre the inductors .
N-Channel:
i dont think thats its a good idea to use 1 corefor both output inductors.
next time u're making a board , make sure to make the power lines first , then connect the low current signals using those "jumpers" if needed .
i also think that the caps should be aftre the inductors .
N-Channel:
i dont think thats its a good idea to use 1 corefor both output inductors.
The inductors should go before the capacitors in the output side. You will really need them if you want the output voltage to be regulated and duty cycle is not always near 50%.
Using the same core for both output inductors as N-Channel recommends has an advantage: cross regulation. However, you must be very careful in order to have exactly the same number of turns (bifilar winding is recommended) and flux in the right direction.
I have built a offline SMPS with very similar secondary side and independent 47uH inductors work well, anyway.
Using the same core for both output inductors as N-Channel recommends has an advantage: cross regulation. However, you must be very careful in order to have exactly the same number of turns (bifilar winding is recommended) and flux in the right direction.
I have built a offline SMPS with very similar secondary side and independent 47uH inductors work well, anyway.
Good Coupling
Actually, I think it is a good idea to couple the output inductors on (+/-) symmetric supplies like those for audio. This idea is born out of the fact that the BIG yellow toroid after the output rectifiers in almost every AT & ATX box is cross-coupled between the +5V, +12V, -5V, and -12V (and +3.3V) outputs. Rationale: if one output is loaded down the others will respond in kind. For your purposes of the (+/-) outputs, it keeps them symmetrical even if only one rail is momentarily loaded down from a sudden big draw in current. (Whew! Now I can breathe!)
Thoughts?
BTW, I'm suprised that EVA hasn't chimed in yet. She always has something very useful to add to the mix..... Earth calling EVA....
Actually, I think it is a good idea to couple the output inductors on (+/-) symmetric supplies like those for audio. This idea is born out of the fact that the BIG yellow toroid after the output rectifiers in almost every AT & ATX box is cross-coupled between the +5V, +12V, -5V, and -12V (and +3.3V) outputs. Rationale: if one output is loaded down the others will respond in kind. For your purposes of the (+/-) outputs, it keeps them symmetrical even if only one rail is momentarily loaded down from a sudden big draw in current. (Whew! Now I can breathe!)
Thoughts?
BTW, I'm suprised that EVA hasn't chimed in yet. She always has something very useful to add to the mix..... Earth calling EVA....
Re: Good Coupling
Eva S.O.S!!
i dont think that one inductor on both outputs will work .
N-Channel:
where did u see an ATX power supply with negative rails?
N-Channel said:
BTW, I'm suprised that EVA hasn't chimed in yet. She always has something very useful to add to the mix..... Earth calling EVA....
Eva S.O.S!!
i dont think that one inductor on both outputs will work .
N-Channel:
where did u see an ATX power supply with negative rails?
Thank You, EVA! 
sss,
Just crack open any full-size 230W or greater AT or ATX (Not ITX- they're smaller, and, I believe, do not have -5V and -12V sections.). OK, OK, technically, they're not rails in the sense that they are realtively low-current (< 500mA). For the sake of the discussion here, though, I refer to them rails. The blue wire is -12V, and the white wire is -5V.
sss,
Just crack open any full-size 230W or greater AT or ATX (Not ITX- they're smaller, and, I believe, do not have -5V and -12V sections.). OK, OK, technically, they're not rails in the sense that they are realtively low-current (< 500mA). For the sake of the discussion here, though, I refer to them rails. The blue wire is -12V, and the white wire is -5V.
I would explain it in terms of magnetic amplification. When one output is loaded down, it moves the inductor toward saturation, making its impedance less. But at the same time, the transformer is loaded down more, tending to drop all the output voltages. However, referring back to the inductor, the cross-coupling lowers the impedance of the inductor for those outputs as well as the one under load, compensating for the load on the transformer. Well, I see it this way though I wonder if I explained it right.
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