i'm about to build this amp for a school project http://www.redcircuits.com/Page2.htm
what do you think about the design, can it be improved, does it need to be improved? i'm not going for some hi power, i'd rather have better sound quality. i'm building this one, cause i can find all the components for it... i'm planning to run it from a pc, does it need a preamp, or maybe something to reduce the signal from the sound card?
any suggestions would be nice
cheers
what do you think about the design, can it be improved, does it need to be improved? i'm not going for some hi power, i'd rather have better sound quality. i'm building this one, cause i can find all the components for it... i'm planning to run it from a pc, does it need a preamp, or maybe something to reduce the signal from the sound card?
any suggestions would be nice
cheers
redcircuits Red Free Circuit Designs IRF530 HEXFET
this has been discussed and even warned a bit for
several times, several different years
the hookup, bad thing,
is that only a variable resistor R11 is used
to control the idle current in output stage
for your own safety and your transistor safety
you should, if you know how to:
Replace R11 with a VBE multiplier ( trimpot + transistor put onto heatsink, to sense high temperature )
This is highly important advice
if you use any of the specified IRF530 / IRF9530
or any other HEXFET, IRFxxx output FET transistors
And this warning is not only from me, but from others who had a look at this schematic.
For find more topics regarding this hazardous amplifier,
that is nothing to play with, for those who does not know these things mentioned:
SEARCH this Solid State forum: http://www.diyaudio.com/forums/search.php
Use Search Keyword like:
redcircuits
Red Free Circuit designs
HEXFET
IRF530
IRF9530
Regards
lineup
this has been discussed and even warned a bit for
several times, several different years
the hookup, bad thing,
is that only a variable resistor R11 is used
to control the idle current in output stage
for your own safety and your transistor safety
you should, if you know how to:
Replace R11 with a VBE multiplier ( trimpot + transistor put onto heatsink, to sense high temperature )
This is highly important advice
if you use any of the specified IRF530 / IRF9530
or any other HEXFET, IRFxxx output FET transistors
And this warning is not only from me, but from others who had a look at this schematic.
For find more topics regarding this hazardous amplifier,
that is nothing to play with, for those who does not know these things mentioned:
SEARCH this Solid State forum: http://www.diyaudio.com/forums/search.php
Use Search Keyword like:
redcircuits
Red Free Circuit designs
HEXFET
IRF530
IRF9530
Regards
lineup
a
GOOD alternative:
Take a look at this well documented amplifier project, in details!
This is totally safe and sound
and besides one of the nicest articles I have ever seen
describing how to build a good amplifier
with reasonable output power
(not too much and not too little power WATT for normal speakers)
It is a fairly simple amplifier, even good for a beginner.
Still it is not so simple it is bad.
I am actually quite sure it is a very good amplifier!
Because reading those texts and see those details described
The Author might as well be a teacher
in A Power Amplifier School.
The people of Denmark can make good amplifiers,
as well as loudspeakers ( VIFA and Scan-Speak! )
for sure!
25 W DIY Power Amplifier - Try something simple for a change
These pages are written and maintained by Mads K. Madsen, Denmark
Good Luck, pudge667
from
lineup
Lineup Amplifier Laboratory
http://lineup.awardspace.com/
GOOD alternative:
Take a look at this well documented amplifier project, in details!
This is totally safe and sound
and besides one of the nicest articles I have ever seen
describing how to build a good amplifier
with reasonable output power
(not too much and not too little power WATT for normal speakers)
It is a fairly simple amplifier, even good for a beginner.
Still it is not so simple it is bad.
I am actually quite sure it is a very good amplifier!
Because reading those texts and see those details described
The Author might as well be a teacher
in A Power Amplifier School.
An externally hosted image should be here but it was not working when we last tested it.
The people of Denmark can make good amplifiers,
as well as loudspeakers ( VIFA and Scan-Speak! )
for sure!
25 W DIY Power Amplifier - Try something simple for a change
These pages are written and maintained by Mads K. Madsen, Denmark
Good Luck, pudge667
from
lineup
Lineup Amplifier Laboratory
http://lineup.awardspace.com/
pudge667 said:
Yes it MUST be improved, the bias current generator (single trim pot) is DANGEROUS, if any IRF or IRFP part is used. It would work with something like a 2SJ162/2SK1058 pair but that will be very expensive (~110KN for each pair).
In fact, this schematic has been developed to use the 2SJ162/2SK1058 LATERAL MOSFETs and (pardon my language) some idiot has simply replaced the labeling with IRFxxx, and now it keeps popping up allover he internet. Whoever has done so has no idea anout how what type of MOSFET works. Vertical MOSFETs (like IRFxxx) must be temperature compensated or will spontaneously increase their bias current as they heat up until something goes up in smoke.
To fix this, and use IRF parts, you need tio do the following:
Remove R11 from the schematic.
Buy the following parts:
1) IRF510, 520, 610 or even another IRF530, call it Q10
2) One 2.5k trim pot, instead of R11
3) Two 1.2k resistors, call them R19 and R20
Replace R11 with the above, connected as follows:
1) Drain of Q10 and one end of R19 to collector of Q6 (and other components on schematic)
2) Gate of Q10 to other end of R19 and counter-clockwise side of R11 trimmer
3) Source of Q10 to clockwise side of R11 trimmer and colelctor of Q7 (and other components that conenct to it in the original schematic)
4) R20 between counter-clockwise side of R11 trimmer and wiper (middle pin) of R11 trimmer.
Initially put the trimmer in fully counter-clockwise position. This will put the idle current of the output transistors at zero. Turning clockwise will increase it to the desired current, this will still be between 50-150mA.
5) Q10 MUST be mounted on the same heatsink and in close proximity to the output transistors Q8 and Q9, because it must be at the same temperature.
Also, to prevent gate destruction f the IRF MOSFETs at overcurrent:
Get two zener diodes, 5.6-6.2V (small size is fine)
Connect the diodes in series (A of the first to K of the second)
Connect the free K lead of this series combination to gate of IRF530, the free A lead to the gate of IRF9530, and the middle joint of the two zeners to the output of the amplifier (joined sources of the IRF530 and 9530).
Again, this is needed because the original 2SJ162/2SK1058 for which the schematic was made, have internal zeners, but IRFxxx do not, so they must be added outside.
This should be enough for a good start. Even with these modifications it is far from the ideal amp, but I think it will be more than fine to amplify the output of a PC.
Re: how about THIS AMP
Well just a suggestion. At this link,(http://www.pcpaudio.com/pcpfiles/proyectos_amplificadores/public/public.html) all information on pcb artwork and adjustment to suit output power is listed.
Maybe one could find it as a good initial project.
Cheers,
RSK
Well just a suggestion. At this link,(http://www.pcpaudio.com/pcpfiles/proyectos_amplificadores/public/public.html) all information on pcb artwork and adjustment to suit output power is listed.
Maybe one could find it as a good initial project.
Cheers,
RSK
Thanks, Lineup.
I made a search and found one of our member(Raka) has done it.(http://www.diyaudio.com/forums/showthread.php?s=&threadid=28932).Probably a good sounding piece of electronics.
Therefore its a proven design.
Cheers,
RSK.
I made a search and found one of our member(Raka) has done it.(http://www.diyaudio.com/forums/showthread.php?s=&threadid=28932).Probably a good sounding piece of electronics.
Therefore its a proven design.
Cheers,
RSK.
For circa 25W I'd try a gainclone. You can probably get the IC's off the Natsemi website as samples. If you go to the chip amp forum on this website, you'll find plenty of circuits and board layouts. These devices are easy to use and give superb performance for the effort. I've built two to replace the power amp section of a Marantz PM68 - great sound (I had to repalce the transformer as well since the PM68 has 57V rails and the Gainclone needed 25V).
If you want to build something with more power, then go discrete.
If you really want to go discrete in any event, try the JLH designs - search the forum - there are lots of memebers who have built this amp (10W only, but very good sound from what I've heard).
By the way, looking at the schematics on this thread, I'd agree with some of the comments - there are better designs out there.
Good luck.
If you want to build something with more power, then go discrete.
If you really want to go discrete in any event, try the JLH designs - search the forum - there are lots of memebers who have built this amp (10W only, but very good sound from what I've heard).
By the way, looking at the schematics on this thread, I'd agree with some of the comments - there are better designs out there.
Good luck.
thank you for all your help people, guess i'm gonna go for K. Madsen's amp, it seems to be very well documented, and since you recommended it i'm gonna give it a try, and I seem to have the most of the parts for it at my disposal, so i won't spend much on building it!
if i have any questions about this amp, i'll ask here again
cheers
if i have any questions about this amp, i'll ask here again
cheers
pudge667 said:
.ps
postscript files
Download postscript files Reader, Viewer
It is free.
I use this most wellknown reader, GhostScript - think most uses this one:
http://www.cs.wisc.edu/~ghost/gsview/
========================================
about
.prn
printer files
those are files for your printer
think even is mentioned at Mads K. Madsen site
you can send such a file to printer,
using a direct Run Command Line in your PC
and the printer will print out 'xxxxxxx.prn' file
of course you download that file to your PC first
========================================
lineup
can you explain me some things?
so i'm building the madsen amp http://members.hometown.aol.com/_ht_a/lmdmkm/25w/25wamp.htm
now there are a few thing i don't understand:
1) about he pcb, it says "The PCB is single sided to make it easier for DIYs to make, but it of cause results in some jumpers on the board."
Could you translate that for me? English please! Are there any jumpers on the board, or is the pcb on the web site complete?
2) I'm not sure how to read some of the resistor values, like: 5k62 0.25 W 1%, is that 5,62kΩ
or 1K00 0.25 W 1%, is that 1kΩ
or 34R8 220R 0.25 W 1%, what's that?
3) In the parts table it's written
C10 -- 220uF / 35 V 100uF / 25 V E-Lyt. (2 modul) (2 modul)
so is it 220uF or 100uF, or both maybe? What does 2 modul mean?
Please any help?
Cheers
so i'm building the madsen amp http://members.hometown.aol.com/_ht_a/lmdmkm/25w/25wamp.htm
now there are a few thing i don't understand:
1) about he pcb, it says "The PCB is single sided to make it easier for DIYs to make, but it of cause results in some jumpers on the board."
Could you translate that for me? English please! Are there any jumpers on the board, or is the pcb on the web site complete?
2) I'm not sure how to read some of the resistor values, like: 5k62 0.25 W 1%, is that 5,62kΩ
or 1K00 0.25 W 1%, is that 1kΩ
or 34R8 220R 0.25 W 1%, what's that?
3) In the parts table it's written
C10 -- 220uF / 35 V 100uF / 25 V E-Lyt. (2 modul) (2 modul)
so is it 220uF or 100uF, or both maybe? What does 2 modul mean?
Please any help?
Cheers
Hi,
reading resistor values:- the multiplier replaces the decimal point and also avoids the ambiguity between using "." & "," for a decimal point when some nations reserve "," as the thousands separator in large numbers. eg 1,000,000 = one million.
but 1,000 could be either one thousand or one, to four significant figures, depending on your upbringing. Whereas 1M0 and 1k0 are unambiguous. 1R0 = one ohm.
The "modul" is multiples of 0.1inch (2.54mm).
Many of the cap locations have multiple pads for different size (pin to pin pitch) of caps. This is very good because often blinkered designers forget that some sizes are difficult to obtain particularly if trying to source from just a few suppliers.
C10 can use Either 100uF or 220uF. I would try to source the larger value IF it fits the PCB.
The Vbe multiplier is wrong.
The pot P1 is shown in the wrong side of the resistor ladder.
Two solutions.
Either swap loactions of P1 and R16 (2k0)
or
change Q8 to PNP (BD140), but ensure it is the correct way round.
I think C1 is too small use 2u2F.
The thick balck lines are wire links (about 11).
By the way (BTW) the site is well written. read and learn.
reading resistor values:- the multiplier replaces the decimal point and also avoids the ambiguity between using "." & "," for a decimal point when some nations reserve "," as the thousands separator in large numbers. eg 1,000,000 = one million.
but 1,000 could be either one thousand or one, to four significant figures, depending on your upbringing. Whereas 1M0 and 1k0 are unambiguous. 1R0 = one ohm.
The "modul" is multiples of 0.1inch (2.54mm).
Many of the cap locations have multiple pads for different size (pin to pin pitch) of caps. This is very good because often blinkered designers forget that some sizes are difficult to obtain particularly if trying to source from just a few suppliers.
C10 can use Either 100uF or 220uF. I would try to source the larger value IF it fits the PCB.
The Vbe multiplier is wrong.
The pot P1 is shown in the wrong side of the resistor ladder.
Two solutions.
Either swap loactions of P1 and R16 (2k0)
or
change Q8 to PNP (BD140), but ensure it is the correct way round.
AAgh, this stops BD140 being used. Must swap P1 and R16.
I think C1 is too small use 2u2F.
The thick balck lines are wire links (about 11).
By the way (BTW) the site is well written. read and learn.
ok, i was pretty sure how to read the resistor values, but i asked because of this. R14 is 68R1 0.25 W 1%, so where do i find 68R1 resistor? will it be ok if i use approximately the same resistor value, or must i use 68R1 resistor?
and R18 is 220R 220R 0.25 W 1%, so should i use two 220R resistors in series, or what? why is 220R written two times?
would you explain this please?
thanks for your help so far!
and R18 is 220R 220R 0.25 W 1%, so should i use two 220R resistors in series, or what? why is 220R written two times?
would you explain this please?
thanks for your help so far!
Hi,
the pot is usually shown in the resistor leg corresponding to the base - emitter side of the multiplier.
Here, if the wiper goes open circuit the Vbe multplier voltage drops to minimum.
If the pot is inserted in the collector - base side, then if the wiper goes open circuit then the voltage goes to maximum and the quiescent current through the output stages rises enormously and overheats, probably to destruction, if other protection does not shut down the amplifier.
I think R17 & R18 are 100r from the schematic.
The duplication 220/220 is just a typo. Look at the schematic and the layout.
The chosen resistor values are generally E96 series, rather than the more usual and easier to obtain E24 series.
E96 are often reserved for 0.1% tolerance but here he has specified 1% tolerance.
68r1 +- 1% covers the range 64r42 to 68r78. He is telling you that any resistor in that range will operate correctly. You can choose an E24 series resistor value of 68r and it will work perfectly. There is little need for precision in most of the resistors used in this circuit.
the pot is usually shown in the resistor leg corresponding to the base - emitter side of the multiplier.
Here, if the wiper goes open circuit the Vbe multplier voltage drops to minimum.
If the pot is inserted in the collector - base side, then if the wiper goes open circuit then the voltage goes to maximum and the quiescent current through the output stages rises enormously and overheats, probably to destruction, if other protection does not shut down the amplifier.
I think R17 & R18 are 100r from the schematic.
The duplication 220/220 is just a typo. Look at the schematic and the layout.
The chosen resistor values are generally E96 series, rather than the more usual and easier to obtain E24 series.
E96 are often reserved for 0.1% tolerance but here he has specified 1% tolerance.
68r1 +- 1% covers the range 64r42 to 68r78. He is telling you that any resistor in that range will operate correctly. You can choose an E24 series resistor value of 68r and it will work perfectly. There is little need for precision in most of the resistors used in this circuit.
so i should do this?
http://img292.imageshack.us/my.php?image=modshhq0.jpg
switch places of R16 and P1? that would require some PCB modification, right? why doesn't the author mention nothing about this on his site?
the pot would look like this right?
http://tinyurl.com/yg5y2b
i should use elements from the schematic, not the ones listed on the site?
cheers
http://img292.imageshack.us/my.php?image=modshhq0.jpg
switch places of R16 and P1? that would require some PCB modification, right? why doesn't the author mention nothing about this on his site?
the pot would look like this right?
http://tinyurl.com/yg5y2b
i should use elements from the schematic, not the ones listed on the site?
cheers
if i use 3055 and 2955 instead of bd249 and bd250 do i have to change any other parts, or do i just solder these transistors instead?
how would it be the best to make volume control for this amp. i'm building two channels, and it would be nice to contro volume on both channels with just one knob (pot or whatever)
any advice?
cheers
how would it be the best to make volume control for this amp. i'm building two channels, and it would be nice to contro volume on both channels with just one knob (pot or whatever)
any advice?
cheers
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