Your all V-FET's have the same T-54 rank.
Imho Mr. Pass DUT diagram is more close to real work condition of the amplifier.
Make them hot for 15 minutes , temperature stabilise on the heatsink
then take Vgs measurements.
Sony VFET Amplifier Part 2
Greetings
Attachments
Sony VFET Amplifier Part 2
Sony VFET Amplifier Part 2
Sony VFET Amplifier Part 2
You can use two 19 Volts laptop psu's connected together for bipolar
(-) (0 Volts, center tap ) and (+).
Two bench lab psu's ( current limited 1A max ) are always great tools.
My setup on the pictures 🙂
Sony VFET Amplifier Part 2
Sony VFET Amplifier Part 2
You can use two 19 Volts laptop psu's connected together for bipolar
(-) (0 Volts, center tap ) and (+).
Two bench lab psu's ( current limited 1A max ) are always great tools.
My setup on the pictures 🙂
Attachments
@soundhappy, I love your picture... it's worth 1000 words.
Thank you for the links. I'm excited to make this amp. It will be the most complicated that I've built.
Thank you for the links. I'm excited to make this amp. It will be the most complicated that I've built.
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Anybody can give idea
Will this amp work optimal with 8 ohm 89 db jbl L166? Reasonably loud level
Thank you
Will this amp work optimal with 8 ohm 89 db jbl L166? Reasonably loud level
Thank you
RodeoDave thanks for this. I'm ready for the first stage of power up.
Just to double confirm, on the ZTX450/550, the round side is the side with the writing on it?
Ok, so I was able to confirm orientation from datasheets, where I should have gone in the first place!
I've powered up both boards, and with 510r in r34/35 I get around 4.7v across both r34/35 on both boards.
How do I ascertain Jfet idss from this and adjust r34/35?
My voltages are way off from the initial voltages as noted by Nelson. I'm using the Fairchild JFets
I've powered up both boards, and with 510r in r34/35 I get around 4.7v across both r34/35 on both boards.
How do I ascertain Jfet idss from this and adjust r34/35?
My voltages are way off from the initial voltages as noted by Nelson. I'm using the Fairchild JFets
There are no source resistors on the jfets so there are running at Idss.
So the voltage drop across R34/R35 is just the Idss times the resistance.
So the current is 4.7V/510 ohm ~ 9.2mA
A lot of numbers are different because with 510R for R35/R34 your mosfets are
now on. (See T6-T7 and T8-T9 voltages).
But things like G-T6 and G-T8 shouldn't change since those are just the rail voltages.
G-T4 and G-T2 also shouldn't change.
Please check these, as well as your raw DC rail voltages.
So the voltage drop across R34/R35 is just the Idss times the resistance.
So the current is 4.7V/510 ohm ~ 9.2mA
A lot of numbers are different because with 510R for R35/R34 your mosfets are
now on. (See T6-T7 and T8-T9 voltages).
But things like G-T6 and G-T8 shouldn't change since those are just the rail voltages.
G-T4 and G-T2 also shouldn't change.
Please check these, as well as your raw DC rail voltages.
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Something's not right. G-T6 should be pretty much the full positive supply voltage of 28V.
We need to see pics of the PSU, including transformer wiring.
We need to see pics of the PSU, including transformer wiring.
It looks consistent with setting 28V and getting +/-14V.
I think it's now time to pull out the transformer, caps and the
real power supply. 🙂
I think it's now time to pull out the transformer, caps and the
real power supply. 🙂
OK, very noob mistake then!!! Oops.
I'm repurposing my Aleph J PSU, I've a new transformer. I build up the PSU and report back.
I'm repurposing my Aleph J PSU, I've a new transformer. I build up the PSU and report back.