fakes really bad luck
I dont have test with BC and 2 SC 1845 like in schematic from quasi
2 sc 2240 and MPSA 42/92 in NMOS working very good
NMOS is working with all MJE or 2SA / 2SC or 2SD / 2SB if not... then you have fakes or faults in pcb
bought last year all parts for NMOS very cheap in Shenzen/China
25 Mosfets IRFP460 in USD about 0,70 USD pcs.
Metal film 0,6W Resistors minimum is 200 pcs. in USD about 2,50 USD for 200 pcs.
provide us pictures from your PCB
I dont have test with BC and 2 SC 1845 like in schematic from quasi
2 sc 2240 and MPSA 42/92 in NMOS working very good
NMOS is working with all MJE or 2SA / 2SC or 2SD / 2SB if not... then you have fakes or faults in pcb
bought last year all parts for NMOS very cheap in Shenzen/China
25 Mosfets IRFP460 in USD about 0,70 USD pcs.
Metal film 0,6W Resistors minimum is 200 pcs. in USD about 2,50 USD for 200 pcs.
provide us pictures from your PCB
so i will provide fastest i can. I think i should look up for some mje.By now my PCB is getting tired of replacing components.I will try to find good source of MJE,especially that my are isolated and may dissipate heat poorly,and this is first sign of fake.How about matching FETs? Did it anybody?or everybody has much more luck?
thanks every body for the reply...... one query can I use a single big heat sink for stereo operation.....??
Yes you can, I did take big single heat sink from 2 HE PA Amplifier
and SMPS Power Board +/- 80 V from PA Amplifier
@adamkaktus I think you have fault in PCB check all B C E Connection and HFE with Transistor tester, it can be fault in datasheet too .....
Before I did buy in germany MJE 340/350 with poor big difference HFE 15 and 120 its not a joke...
How about matching FETs? forget it, you dont need
actually Im writing this message and my NMOS producing earthquake in Bass...have 3 NMOS working now 1 for bass and 2 for stereo operation
I can hear details in music .... I did never heart before
heatsinks are about 30 degress after 2 hours
and SMPS Power Board +/- 80 V from PA Amplifier
@adamkaktus I think you have fault in PCB check all B C E Connection and HFE with Transistor tester, it can be fault in datasheet too .....
Before I did buy in germany MJE 340/350 with poor big difference HFE 15 and 120 its not a joke...
How about matching FETs? forget it, you dont need
actually Im writing this message and my NMOS producing earthquake in Bass...have 3 NMOS working now 1 for bass and 2 for stereo operation
I can hear details in music .... I did never heart before
heatsinks are about 30 degress after 2 hours
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I checked for differences this mje, 2sc and bc's. They're just like in their datasheets, also schematic is exactly similar to layout. Hfe of Mje 340 still about 67-76, Mje350 is ~150. I crushed 2 psc of this mje from fairchild, the same 2x2mm structure in both, soldered to copper-like collector. I'm going to find them in non-isolated to-126, from STM, it may not be a fake. Also i consider making new pcb, just like first, but on fiberglass base, not from epoksy-wire should be stronger, and i'm going to do this better. Old one is extremly exhausted of replacing parts-IRF's are difficult to unsolder. I also consider buying something from Mje 150XX series, is it possible to mach them on original PCB from Quasis project? Has anybody working PCB for 4 pairs of Fets-maybe it could be better grounded.
Thanks for any response.
A.
Thanks for any response.
A.
Mje 340 still about 67-76, Mje350 is ~150
ist not good, difference is to big use another devices
difference with my transistor in hfe between PNP and NPN is about 10
send pictures from pcb
ist not good, difference is to big use another devices
difference with my transistor in hfe between PNP and NPN is about 10
send pictures from pcb
Hi qsa!
Thanks for sharing the equivalent or replacement transistors. I have done my Nmos with above mention replacement parts. Sounds amazing very clear crisp sound with deep punch when I use this as Sub Woofer Amp.
But when I use this as full range amp I feel missing full range especially high frequency. Is it due to 2SB 649/2Sd669 character? Also I used 2sc 1845 in place 2SC2240. Suggestions appreciated
Vijay
Thanks for sharing the equivalent or replacement transistors. I have done my Nmos with above mention replacement parts. Sounds amazing very clear crisp sound with deep punch when I use this as Sub Woofer Amp.
But when I use this as full range amp I feel missing full range especially high frequency. Is it due to 2SB 649/2Sd669 character? Also I used 2sc 1845 in place 2SC2240. Suggestions appreciated
Vijay
Hello vijay_meyou
> Is it due to 2SB 649/2Sd669 character?
I dont know is it a good idea to use MJE 340/350.... because I dont know the NMOS Sound with devices like in quasis schematic
> But when I use this as full range amp I feel missing full range especially high frequency.
I cant confirm this....Sound from my NMOS is very excellent in high frequency
...I think you should check your capacitors
have replace CLASS D Amp with NMOS, trust me NMOS is sounding better in high frequency and music details
1 pcs. working NMOS has 2SC 2240 for Input - all another small signal transistors MPSA 42 / 92 - MJE15034 and MJE15035 in VAS and Driver Stage BD 139 for VBE
and another NMOS
1 pcs. working NMOS has 2SC 2240 for Input - all another small signal transistors MPSA 42 / 92 - 2SB 649A / 2SD 669A in VAS, 2SA1837 / 2SC4793 in Driver Stage, BD 139 for VBE
I cant hear difference in Sound between this two NMOS with different devices
Replacement for BD 139 if not possibile 2SD669A OR MJE 180
all this devices are very popular by amplifier manufacturer easy to get and very very cheap
have change devices in NMOS for HIGHER VOLTAGE use about +/- 100 -130V DC
actually cant test with HIGHER VOLTAGE because have only here +/- 85 V DC SMPS Power Board
> Is it due to 2SB 649/2Sd669 character?
I dont know is it a good idea to use MJE 340/350.... because I dont know the NMOS Sound with devices like in quasis schematic
> But when I use this as full range amp I feel missing full range especially high frequency.
I cant confirm this....Sound from my NMOS is very excellent in high frequency
...I think you should check your capacitors
have replace CLASS D Amp with NMOS, trust me NMOS is sounding better in high frequency and music details
1 pcs. working NMOS has 2SC 2240 for Input - all another small signal transistors MPSA 42 / 92 - MJE15034 and MJE15035 in VAS and Driver Stage BD 139 for VBE
and another NMOS
1 pcs. working NMOS has 2SC 2240 for Input - all another small signal transistors MPSA 42 / 92 - 2SB 649A / 2SD 669A in VAS, 2SA1837 / 2SC4793 in Driver Stage, BD 139 for VBE
I cant hear difference in Sound between this two NMOS with different devices
Replacement for BD 139 if not possibile 2SD669A OR MJE 180
all this devices are very popular by amplifier manufacturer easy to get and very very cheap
have change devices in NMOS for HIGHER VOLTAGE use about +/- 100 -130V DC
actually cant test with HIGHER VOLTAGE because have only here +/- 85 V DC SMPS Power Board
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Substitute for VAS MJE 340/350 should be 2SA1406/2SC3600 or BF 871/872 too
Check what you can get from dealer in your country, normally you can change devices without problems
Check what you can get from dealer in your country, normally you can change devices without problems
Hi qsa,
Thanks for your quick reply.
May be you are right. I used capacitors form my old salvage boards. Today i will re build my NMOS with all new capacitors. Also need to check the availability of 2SA1406/2SC3600.
Can you advice any matching preamplifier with buffer or gain boost for NMOS amp? if any circuits are PCB layout available to build please send me.
Thanks
Vijay
Thanks for your quick reply.
May be you are right. I used capacitors form my old salvage boards. Today i will re build my NMOS with all new capacitors. Also need to check the availability of 2SA1406/2SC3600.
Can you advice any matching preamplifier with buffer or gain boost for NMOS amp? if any circuits are PCB layout available to build please send me.
Thanks
Vijay
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Here latest PCB Layout from NMOS
If interest for professional NMOS PCB from PCB supplier like in PDF file send me email
changes compare to original quasi design are
1. different semiconductor devices look previous postings
2. have add VI Limiter, Crowbar DC Protection, Electronic Turn on/off - No output Relay necessarily,
Size: 220 x 80
If interest for professional NMOS PCB from PCB supplier like in PDF file send me email
changes compare to original quasi design are
1. different semiconductor devices look previous postings
2. have add VI Limiter, Crowbar DC Protection, Electronic Turn on/off - No output Relay necessarily,
Size: 220 x 80
power amp under development
hi qsa
greetings nice pcb just want to know afew things
1 can 6 output pairs be used
2 rail voltage using 6 output pairs max supply voltage and your suggested voltage
3 biasing method and quiescent current
4 have you revised the orignal circuit or please can you post latest schematic
i am trying to make single sided design diy design double sided pcb is very
expensive to make
thanking you
andrew lebon
hi qsa
greetings nice pcb just want to know afew things
1 can 6 output pairs be used
2 rail voltage using 6 output pairs max supply voltage and your suggested voltage
3 biasing method and quiescent current
4 have you revised the orignal circuit or please can you post latest schematic
i am trying to make single sided design diy design double sided pcb is very
expensive to make
thanking you
andrew lebon
<Here latest PCB Layout from NMOS
If interest for professional NMOS PCB from PCB supplier like in PDF file send me email
changes compare to original quasi design are
1. different semiconductor devices look previous postings
2. have add VI Limiter, Crowbar DC Protection, Electronic Turn on/off - No output Relay necessarily,
-----------------
Hi qsa,
Nice layout with all protections,thankyou for posting. I will study this and try. it would good if i get some seperate input preamp circuit layout so that i can use the orginal quasi layout which i already have. (home made PCB)
Thanks
Vijay Daniel.
If interest for professional NMOS PCB from PCB supplier like in PDF file send me email
changes compare to original quasi design are
1. different semiconductor devices look previous postings
2. have add VI Limiter, Crowbar DC Protection, Electronic Turn on/off - No output Relay necessarily,
-----------------
Hi qsa,
Nice layout with all protections,thankyou for posting. I will study this and try. it would good if i get some seperate input preamp circuit layout so that i can use the orginal quasi layout which i already have. (home made PCB)
Thanks
Vijay Daniel.
hey every body ........... I just completed assembling the nmos using home made pcb ,
I am using IRF540N as O/p device , a 25-0-25V transformer...... But there seems to be problem I am getting 35V dc in the output .... Although nothing seems to blown as every thing is running cold ....... can any body point out the source of error as I am new to this field...... plz advise
I am using IRF540N as O/p device , a 25-0-25V transformer...... But there seems to be problem I am getting 35V dc in the output .... Although nothing seems to blown as every thing is running cold ....... can any body point out the source of error as I am new to this field...... plz advise
had similar problem in my second nmos....fault was reversed PIN from VBE
check all BCE PIN from transitors
if nothing fault in devices or reversed PIN amplifier is working
check all BCE PIN from transitors
if nothing fault in devices or reversed PIN amplifier is working
thanks qsa will check it at morning ..... its 3.00 am .... was trying to figure out the problem ......
regards
sekhar
regards
sekhar
@ vijay_meyou *
> I feel missing full range especially high frequency.
against gate capacitance / charge and discharge gates
I forgot to tell you …... drive gates with high current driver... Mje 340/350 is not a good choice in NMOS as driver, because Mosfets need high peak current for charge and discharge gates
use as driver MJE 15030- 34 / 2SA 1837 - 2SC4793 or similar it should solve your high frequency full range problem if it really exist.. ?
@ andrewlebon *
> hi qsa greetings nice pcb
thank you was a lot of work...
> just want to know afew things
> can 6 output pairs be used
yes, you need to add more devices for high output power or 2 OHM use
> 2 rail voltage using 6 output pairs max supply voltage and your suggested voltage
100 V +/- DC and 10 output pairs IRF 460 should work stable, dont have tested, dont have here 100 +/- DC SMPS
> 3 biasing method and quiescent current
look quasis construction guide
> 4 have you revised the orignal circuit or please can you post latest schematic
attachment latest schematic
> i am trying to make single sided design diy design double sided pcb is very
expensive to make
single sided design, no thanks, …. ! PCB will be to big and cost increase for big pcb
thanking you
andrew lebon
have add crowbar and electronic turn on/off, you dont need relay for turn on/off and DC protect
attachment schematic
> I feel missing full range especially high frequency.
against gate capacitance / charge and discharge gates
I forgot to tell you …... drive gates with high current driver... Mje 340/350 is not a good choice in NMOS as driver, because Mosfets need high peak current for charge and discharge gates
use as driver MJE 15030- 34 / 2SA 1837 - 2SC4793 or similar it should solve your high frequency full range problem if it really exist.. ?
@ andrewlebon *
> hi qsa greetings nice pcb
thank you was a lot of work...
> just want to know afew things
> can 6 output pairs be used
yes, you need to add more devices for high output power or 2 OHM use
> 2 rail voltage using 6 output pairs max supply voltage and your suggested voltage
100 V +/- DC and 10 output pairs IRF 460 should work stable, dont have tested, dont have here 100 +/- DC SMPS
> 3 biasing method and quiescent current
look quasis construction guide
> 4 have you revised the orignal circuit or please can you post latest schematic
attachment latest schematic
> i am trying to make single sided design diy design double sided pcb is very
expensive to make
single sided design, no thanks, …. ! PCB will be to big and cost increase for big pcb
thanking you
andrew lebon
have add crowbar and electronic turn on/off, you dont need relay for turn on/off and DC protect
attachment schematic
Hi Quasi,
i am intrested to build Nmos 350 MkII. but seems it was found on your web site.
what PCb can i use to build this modified schematic posted here. can i have pcb layout for this circuit Nmos 350 mkII.
Thanks
vijay
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Hi vijay_meyou
control board is obsolete, because its all add in current nmos PCB/schematic
like electronic turn on delay / fast off and crowbar dc protect
so we can save cost and space,
actually Im use SMPS +/- 80V DC power board from leight weight PA AMP, small, cost effective and leight weight
heavy transformer and capacitors,,, anymore ...no thanks
control board is obsolete, because its all add in current nmos PCB/schematic
like electronic turn on delay / fast off and crowbar dc protect
so we can save cost and space,
actually Im use SMPS +/- 80V DC power board from leight weight PA AMP, small, cost effective and leight weight
heavy transformer and capacitors,,, anymore ...no thanks
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