If no good, why?
Please, inform the complementary, i have many FETs in my home and i do not know if i can match them to work as complementary.
What is the main characteristics i should observe into the datasheet to decide if they can work together? (studing N type and P type).
Is this mismatch related drain to source resistance something important to worry about?... some of them, for instance, having 0,47 ohms and others having even lower...or higher resistance.
Because of Dudainc kindness and also Anonimous kindness, now a days i have hundreds of power FETs in my home... also BGT power units and drivers.
Thank you,
regards,
Carlos
Please, inform the complementary, i have many FETs in my home and i do not know if i can match them to work as complementary.
What is the main characteristics i should observe into the datasheet to decide if they can work together? (studing N type and P type).
Is this mismatch related drain to source resistance something important to worry about?... some of them, for instance, having 0,47 ohms and others having even lower...or higher resistance.
Because of Dudainc kindness and also Anonimous kindness, now a days i have hundreds of power FETs in my home... also BGT power units and drivers.
Thank you,
regards,
Carlos
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Carlos
I cannot imagine that I am gonna say this to YOU, but......Try it!
Feedback should take care of whatever non-linearities there might be. Try them in maybe in these:
http://www.adam.com.au/cgpap/QuasiWeb/index.htm
...and tell us about it.
Henrik
I cannot imagine that I am gonna say this to YOU, but......Try it!
Feedback should take care of whatever non-linearities there might be. Try them in maybe in these:
http://www.adam.com.au/cgpap/QuasiWeb/index.htm
...and tell us about it.
Henrik
Grollins uses exactly this one and its P-channel in his 25W class A amp here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=120673&highlight=
...even without feedback! So these must be very good for audio.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=120673&highlight=
...even without feedback! So these must be very good for audio.
Yes...there are a lot of readings to be made
I have a new toy to be play with.... i have to clean all that mess to decide if will be fixed or dismounted to use heatskinks and transformer (some capacitors too)
Carlos
I have a new toy to be play with.... i have to clean all that mess to decide if will be fixed or dismounted to use heatskinks and transformer (some capacitors too)
Carlos
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Hi Carlos
Nice kindness to you indeed. Farchild's Q-fets are tough to destroy if you use them properly.
I am using smaller versions in my amp right now, FQP50N06 and FQP47P06. If I can get over 100Wrms from just 2 pair of these little ones, I bet you could build a really BIG amp with all those larger ones but then you may need a medium industrial power feed installed in your home. Neighbors may complain…...
As mentioned before these are really designed for switching and can have a bit of distortion at low current levels due to non linear Vgs vs Id characteristics. If you constructed an EC gate drive circuit, you could alleviate most of those distortions and make a great quality, powerful amp that could drive any speaker load you throw at it (within reason). Matching of P to N types isn't quite as critical with EC, but if you parallel devices you may need to match similar types. I have not tried to match the ones I have because I'm using them as single pairs so I don't know how well they match up, like polarity or as complements.
The
FQA19N20 can dissipate 75W at 100 degrees C.
Because these devices are designed for higher voltage, they have a greater change in Vgs vs Id than the lower voltage ones, wrt current. If they can be matched, you could use them in parallel (+/- 90V) and operate each one with less transconductance. You could use larger source resistors too. This would make their mismatch in minimum Rds-on not as big of a factor since you wouldn’t be operating close to it anyway. I’m afraid that if you did build a proper gate drive circuit, the result could be that you'll never go back to power BJT’s again.
I ain’t an expert, just a few comments on my experience playing with them.
Nice kindness to you indeed.
Farchild's Q-fets are tough to destroy if you use them properly. I am using smaller versions in my amp right now, FQP50N06 and FQP47P06. If I can get over 100Wrms from just 2 pair of these little ones, I bet you could build a really BIG amp with all those larger ones but then you may need a medium industrial power feed installed in your home. Neighbors may complain…...As mentioned before these are really designed for switching and can have a bit of distortion at low current levels due to non linear Vgs vs Id characteristics. If you constructed an EC gate drive circuit, you could alleviate most of those distortions and make a great quality, powerful amp that could drive any speaker load you throw at it (within reason
). Matching of P to N types isn't quite as critical with EC, but if you parallel devices you may need to match similar types. I have not tried to match the ones I have because I'm using them as single pairs so I don't know how well they match up, like polarity or as complements. The FQA19N20 can dissipate 75W at 100 degrees C.
Because these devices are designed for higher voltage, they have a greater change in Vgs vs Id than the lower voltage ones, wrt current. If they can be matched, you could use them in parallel (+/- 90V) and operate each one with less transconductance. You could use larger source resistors too. This would make their mismatch in minimum Rds-on not as big of a factor since you wouldn’t be operating close to it anyway. I’m afraid that if you did build a proper gate drive circuit, the result could be that you'll never go back to power BJT’s again.
I ain’t an expert, just a few comments on my experience playing with them.
I continue unable to assemble Pass amplifiers
Now i have the complementary to the output.....but i have not the complementary small ones.
Now completed 4 years that i use to live with the curiosity about Pass Amplifiers... one day i will build one...for sure i will do that.
Was always a hell in my life this problem.... Nelson uses Fets, from the input to the output, and those folks are not very easy to find here.....now a days i am very rich about power units...but very poor about the input transistors...well...nothing is perfect!... i am glad i already have the output.
I have 2SK170 (Nordic has sent me some...not many)...but not the other one, the complementary small one...maybe i will able to use some to220 Fets i have to substitute them....maybe not...because i think i have not the complementary ones into to220 cases too.
I wish i would be living near you folks... say..without my mail problems.... custom problems...i could give you some power an receive small ones from you....but the customs will block calling non legal importation....grumpf!!! %$@#!*(#¨#%.... a "full ship" of insanity down here, inside this bureaucratic country.... we will never evolute without changing our minds.
Now we have "fast importation and exportation method"... starts offering you a list of needs... documents... bureaucracy, ask business registration number, so, not beeing a business man, only beeing a family man you cannot export or import a single transistor without this "filter" they use... and ask 30 USD by a ridiculous card box used to export, even if inside we are posting a single small transistor... standard thing!
I was thousand miles distant...now i am 3 or 4 miles distant... one day i will be there, assembling some Pass amplifiers..... but i am still travelling with into mind...wait me there folks!
Carlos
.....................................................................................................
Also i have a swedish friend that uses FETs into interesting designs he use to make.... also waiting the day i will manage to have those Fets to produce his schematics...some of them are very nice.
Well... i have made thousands of amplifiers.... and having problems with parts...i am imagining how many i could have made not having the component problems i had in the past...now a days i am wealthy about that stuff..enormous stock of powerfull Fets here...more than 200 units... and all them power units... maybe i still have more transistors "parked" into boxes here than Jacco Vermeullen,,, an the one seems to be a big parts colector.
Now i have the complementary to the output.....but i have not the complementary small ones.
Now completed 4 years that i use to live with the curiosity about Pass Amplifiers... one day i will build one...for sure i will do that.
Was always a hell in my life this problem.... Nelson uses Fets, from the input to the output, and those folks are not very easy to find here.....now a days i am very rich about power units...but very poor about the input transistors...well...nothing is perfect!... i am glad i already have the output.
I have 2SK170 (Nordic has sent me some...not many)...but not the other one, the complementary small one...maybe i will able to use some to220 Fets i have to substitute them....maybe not...because i think i have not the complementary ones into to220 cases too.
I wish i would be living near you folks... say..without my mail problems.... custom problems...i could give you some power an receive small ones from you....but the customs will block calling non legal importation....grumpf!!! %$@#!*(#¨#%.... a "full ship" of insanity down here, inside this bureaucratic country.... we will never evolute without changing our minds.
Now we have "fast importation and exportation method"... starts offering you a list of needs... documents... bureaucracy, ask business registration number, so, not beeing a business man, only beeing a family man you cannot export or import a single transistor without this "filter" they use... and ask 30 USD by a ridiculous card box used to export, even if inside we are posting a single small transistor... standard thing!
I was thousand miles distant...now i am 3 or 4 miles distant... one day i will be there, assembling some Pass amplifiers..... but i am still travelling with into mind...wait me there folks!
Carlos
.....................................................................................................
Also i have a swedish friend that uses FETs into interesting designs he use to make.... also waiting the day i will manage to have those Fets to produce his schematics...some of them are very nice.
Well... i have made thousands of amplifiers.... and having problems with parts...i am imagining how many i could have made not having the component problems i had in the past...now a days i am wealthy about that stuff..enormous stock of powerfull Fets here...more than 200 units... and all them power units... maybe i still have more transistors "parked" into boxes here than Jacco Vermeullen,,, an the one seems to be a big parts colector.
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