I stocked jfets for RF and general use during last period activity. Now coming back to my first love, may some parts find also applications in audio ?
- PN4416
- 2N5486
- BF256
- 2N3823
- BF245
- U410
- 2N4093
- 2N5460G
- 2N3966
- J110G
- 2N5462G
Didn´t read all the datasheet but they are VERY usable in Audio.
Not sure how many of each you have but at least I´d do some matching and labelling so later it´s easier to use them.
Just to avoid drawing a new one for you, this is my basic MosFet matcher.
Can be used for preamp Fets with a simple variation , varying resistor value (its only component 🙂 )
Basic setup is the same, but resistor must be 15k.
What you measure is Vg@1mA , negative bias needed for FET to pass 1mA, a useful value when designing a simple gain stage.
Say you have a basic one, supply is 25V, Load/Drain resistor is 10k (so it drops 10V@1mA), what source resistor do you need to autobias at that current?
Suppose you measured Vg@1mA=-2.2V Then you need a 2k2 source resistor to bias it at the desired 1mA current.
That´s why I suggest you to measure all and attach a little label to each one, or if many, group them by Vg@1mA inside a parts box, group those within 10% or 20% together.
I do that with any "mystery" Fet I get my hands on, saves a lot of wasted time.
Not sure how many of each you have but at least I´d do some matching and labelling so later it´s easier to use them.
Just to avoid drawing a new one for you, this is my basic MosFet matcher.
Can be used for preamp Fets with a simple variation , varying resistor value (its only component 🙂 )
Basic setup is the same, but resistor must be 15k.
What you measure is Vg@1mA , negative bias needed for FET to pass 1mA, a useful value when designing a simple gain stage.
Say you have a basic one, supply is 25V, Load/Drain resistor is 10k (so it drops 10V@1mA), what source resistor do you need to autobias at that current?
Suppose you measured Vg@1mA=-2.2V Then you need a 2k2 source resistor to bias it at the desired 1mA current.
That´s why I suggest you to measure all and attach a little label to each one, or if many, group them by Vg@1mA inside a parts box, group those within 10% or 20% together.
I do that with any "mystery" Fet I get my hands on, saves a lot of wasted time.
hi Buenos Aires 😉
Great value advice with simple tester !
To go further, RF parts have caracteristics adapted for high frequencies. So among above parts, which one can used in audio and for which caracteristic ?
Great value advice with simple tester !
To go further, RF parts have caracteristics adapted for high frequencies. So among above parts, which one can used in audio and for which caracteristic ?
Generally RF devices have high 1/f noise knees, as they don't care about the sub-MHz regime - a device quoted as low noise at 100MHz tells you nothing about their 1kHz behaviour. So a random low noise RF transistor isn't likely to be low noise for audio (unless you are lucky). Audio noise isn't usually in the datasheet for RF transistors anyway.
However devices intended for low jitter oscillators have to have low 1/f knee and low noise across the audio band as low frequency noise in an oscillator creates jitter.
However devices intended for low jitter oscillators have to have low 1/f knee and low noise across the audio band as low frequency noise in an oscillator creates jitter.