Note - current through the LEDs is around 1.7mA, so if you've got 6.9mA through R17, R18, VAS current = 6.9 - 1.7 = 5.2ma
Yes, higher value of R10 will give higher VAS current. You need to reach around 770mV over R17, R18 for having 6mA at VAS collectors.
Be careful with the bias - it will slightly increase at higher VAS current.
Yes i know,but i wonder is it safe this operation for the vas transistors without heatsink?
Right - I normally recommend small snap-on heatsinks for TO-126 devices, running with average power dissipation above, say, 250mW.
For running with no heatsinks, better leave it at 5.2mA - they must be warm already.
I see you post these graphs a lot. May I ask what you see in these and how they help you determine whether or not an amp is working well or not? What are you looking for when you look at them?
Thanks, Terry
Sons of Vhex ver.1.2 2sk146GR
A dual fet 2SK146GR as input fet.
Nice balance.
I think that an offset controlling trimmer is no more necessary.
A dual fet 2SK146GR as input fet.
Nice balance.
I think that an offset controlling trimmer is no more necessary.
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thimios
Excellent work! This design is a winner and with some attention to the power supply and layout, it's likely to get even better. Has anyone done phase and gain margin numbers?.
Excellent work! This design is a winner and with some attention to the power supply and layout, it's likely to get even better. Has anyone done phase and gain margin numbers?.
Hi Nania,
Please see the calculated feedback loop analysis in post #290
ULGF = 2.8MHz
Phase margin = 80 degrees
Gain margin = 16 db
Cheers,
Valery
vzaichenko
Thanks for the link, I'm glad stability shouldn't be an issue. I just noted you sell boards and kits on your website. Is there a board design for the VHex+BT? PM me.
Thanks for the link, I'm glad stability shouldn't be an issue. I just noted you sell boards and kits on your website. Is there a board design for the VHex+BT? PM me.
