Yes, that should work just fine. Did you not get my PM? (Just wondering)chopstuck wrote:If putting a VVR on my cathode biased tweed Super clone, can I use it like zener diode for limiting max voltage too? Darn 365-0-365 PT gives me 440 on the plates. My 6V6 Super clone has a 342-0-342 Pt and 400v on the plates. Would you then use a fixed resistor in series with the pot ?
VVR Circuit Schematic
Moderators: pompeiisneaks, Colossal
Re: VVR Circuit Schematic
Re: VVR Circuit Schematic
Yes, I got your message. I just have no access to it at the moment.
Thanks Dana !
Thanks Dana !
Re: VVR Circuit Schematic
That's cool. I just wanted to make sure you got the info.chopstuck wrote:Yes, I got your message. I just have no access to it at the moment.
Thanks Dana !
Re: VVR Circuit Schematic
i have a quick question - i used an IRF840B based VVR (albeit one without a heatsink because i figured the dissipation would be tiny as compared to its max spec) to scale only the power section of my 2061x w. switchable diode and tube rectification. it worked fantastic for a while... then!
I think it failed, but not in the way i expected - i thought a fuse would blow or something, but in my amp, the only thing that's happened is that the 1M pot has stopped working. the amp plays exactly as it did before the mod.
is this a blown mosfet or simply a burned-out pot? i'll probably replace both, just to make sure. are there any guidelines for distances between components? also, log or linear pots?
thanks all.
I think it failed, but not in the way i expected - i thought a fuse would blow or something, but in my amp, the only thing that's happened is that the 1M pot has stopped working. the amp plays exactly as it did before the mod.
is this a blown mosfet or simply a burned-out pot? i'll probably replace both, just to make sure. are there any guidelines for distances between components? also, log or linear pots?
thanks all.
In the interest of full disclosure, I am Animal Factory Amplification.
Re: VVR Circuit Schematic
The mosfet should always be properly heatsinked.
Use a linear 500V-rated pot - logs are only rated for 250V.
Creepage distance is app. 7 mm @ 500V, so HV components should be spaced by 10 mm or so.
Use a linear 500V-rated pot - logs are only rated for 250V.
Creepage distance is app. 7 mm @ 500V, so HV components should be spaced by 10 mm or so.
Re: VVR Circuit Schematic
Flood, what the wattage rating of the MOSFET means, is that it is the maximum dissipation at 25ºC - which means, that you need to keep the MOSFET at that temperature, to be able to do that. In other words, you need a big ol' heatsink - and probably a fan too!
Re: VVR Circuit Schematic
greekie wrote:Flood, what the wattage rating of the MOSFET means, is that it is the maximum dissipation at 25ºC - which means, that you need to keep the MOSFET at that temperature, to be able to do that. In other words, you need a big ol' heatsink - and probably a fan too!
whoops.
ok, time to make some modifications then.... :-/
In the interest of full disclosure, I am Animal Factory Amplification.
Re: VVR Circuit Schematic
I'm designing the layout for my 2XEL84 Rocket, and I'm down to the last bit - the power supply scaling. I only want to scale the power tubes as I am using a PPIMV , can someone tell me if the attached schem is a correct implementation of this ?
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Re: VVR Circuit Schematic
Duh, nevermind - I realized after I posted this that doing it this way would not scale the screens. I was just looking for a way to implement it without changing the stock power supply too much, maybe I'll just scale the whole thing.
Re: VVR Circuit Schematic
You need to isolate the two power rails with diodes. As it is, when you start to reduce the voltage with the VVR, it may effect the circuit behind it. You are correct you need to move the screen supply as well.
So after the rectifier, two diodes branch off. One goes to the VVR circuit and the plates and choke then screens. The other diode goes to the preamp supply and will not be effected by the VVR control. Now, the normal PSU filters everything after the plates through the choke, so you may think about adding another smaller choke to the preamp branch.
So after the rectifier, two diodes branch off. One goes to the VVR circuit and the plates and choke then screens. The other diode goes to the preamp supply and will not be effected by the VVR control. Now, the normal PSU filters everything after the plates through the choke, so you may think about adding another smaller choke to the preamp branch.