Newbie here. I've simulated the J-Mo 3 headphone amp and was wondering if any of the big silicon carbide mosfets could be used in place of the IRF510
https://www.diyaudio.com/forums/headphone-systems/310544-jfet-mosfet-headphone-amplifier-mo-3-a.html
Doing some reading it looks like they need a higher gate voltage, that I get. But in the simulation it looks like the gate is really dragging down the voltage from the J113. Like it's too much of a load?
Can these mosfets be used at low voltages or are the characteristics just not right for this application?
https://www.diyaudio.com/forums/headphone-systems/310544-jfet-mosfet-headphone-amplifier-mo-3-a.html
Doing some reading it looks like they need a higher gate voltage, that I get. But in the simulation it looks like the gate is really dragging down the voltage from the J113. Like it's too much of a load?
Can these mosfets be used at low voltages or are the characteristics just not right for this application?
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The gate shouldn't load it down much as its a capacitance which is 463pf.
If it is add a gate resistor of 220R.
If it is add a gate resistor of 220R.
Show DC voltages.
ALWAYS check your DC voltages for sanity before you think about the AC action.
I suspect your J1 is bottomed out.
ALWAYS check your DC voltages for sanity before you think about the AC action.
I suspect your J1 is bottomed out.
So you have a 12V supply, you expect some nodes in the "middle" of the amplifier to be around half supply, around 6V.
Instead they are all 0.2V-0.25V. "Bottomed".
And reading J133 data, I don't know how that is possible. And I do not have a model for the STC part.
Instead they are all 0.2V-0.25V. "Bottomed".
And reading J133 data, I don't know how that is possible. And I do not have a model for the STC part.
Unless U1 draws a significant current through its pin 1, the drain voltage of J1 can never be that low. Even with a straight short from J1's drain to its source, you would still get 2.16 V.
If the gate of U1 accidentally got connected to pin 2 and the other terminals to pins 1 and 3, then the bias point makes sense.
Can you check the DC currents through the pins of U1?
If the gate of U1 accidentally got connected to pin 2 and the other terminals to pins 1 and 3, then the bias point makes sense.
Can you check the DC currents through the pins of U1?
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Lines 8 and 9 of the .lib file:
******************D G S
.SUBCKT SCT2450KE 1 2 3
So pin 1 is the drain, pin 2 the gate and pin 3 the source, which, by the way, is the normal order for MOSFETs in Spice netlists.
******************D G S
.SUBCKT SCT2450KE 1 2 3
So pin 1 is the drain, pin 2 the gate and pin 3 the source, which, by the way, is the normal order for MOSFETs in Spice netlists.
