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F4 Beast with hundreds of amperes
F4 Beast with hundreds of amperes
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Old 5th March 2018, 01:40 PM   #11
woofertester is offline woofertester  United States
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Quote:
Originally Posted by Ian Macmillan View Post
That looks better
Thank you for reviewing and correcting.
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Old 5th March 2018, 01:48 PM   #12
Ian Macmillan is offline Ian Macmillan
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You are welcome. Not really my intent to review, I am more interested in what you are doing. Just happened to notice in passing.
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Old 18th March 2018, 02:38 PM   #13
woofertester is offline woofertester  United States
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Default Heat Sinks have arrived

I bought three heatsinks from USA Heatsinks dot com. These are 10.08" long. I ordered three of them 7" tall. The picture is with a 15" ruler on top for perspective.

The only downside I notice so far is that where they are cut is a burr edge. It will require some time to remove all of the burr edges.

The weight of the 10.08" x 7" sink is 6 lbs 12 oz. (3.06 kg).

Some solder proto strip boards will arrive Monday. Then commences soldering up a driver board with K170/J74 inputs and K1058/J162 outputs with an FQP3N30 for a bias spreader.
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Old 22nd March 2018, 07:48 PM   #14
woofertester is offline woofertester  United States
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Most of the parts are here. Did some verifying of voltages and currents of the first two stages and placed those on the drawing.

The input stage idles at 8mA.

The LATFETS idling at 50mA require 0.26V Vgs for the J162 and 0.6V Vgs for the K1058. It would be nice to have matching LATFETs.

No capacitors anywhere.

My guess is that an NTC thermistor will be needed on the heatsink and included in the bias spreader for thermal OPS bias stability.
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Old 22nd March 2018, 07:50 PM   #15
woofertester is offline woofertester  United States
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Default Pic of circuit

Pic
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Old 22nd March 2018, 11:50 PM   #16
Telstar is offline Telstar  Italy
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subscribed. This is just what i need (never liked the IR mosfets)
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Old 22nd March 2018, 11:51 PM   #17
Telstar is offline Telstar  Italy
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Quote:
Originally Posted by woofertester View Post
Since I am going in a different direction than the other F4 beast builders, and I don't want to pollute what L H Quam is doing with the bias analysis, here is the front end of my "Beast with hundreds of amperes".
What are you doing differently? For people that haven't followed the Beast thread?
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Old 23rd March 2018, 12:38 AM   #18
woofertester is offline woofertester  United States
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Quote:
Originally Posted by Telstar View Post
What are you doing differently? For people that haven't followed the Beast thread?
1. I am not using a cascode input state

2. I am using LATFET in the driver stage

3. They are using much higher voltage which makes sense if you want to drive an 8-ohm speaker

4. They are implementing a servo bias much the same as the PL amplifier

5. I am going for super high current output at much lower voltage into very low impedance loads.

One of the intended applications is to drive a low impedance ribbon directly with almost unlimited current.
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Old 23rd March 2018, 12:42 AM   #19
Telstar is offline Telstar  Italy
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I just checked the other thread.
Your design follows better my needs and avoid complications, more like the original F4 but with a single more powerful output pair.
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Old 23rd March 2018, 01:26 AM   #20
woofertester is offline woofertester  United States
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Quote:
Originally Posted by Telstar View Post
I just checked the other thread.
Your design follows better my needs and avoid complications, more like the original F4 but with a single more powerful output pair.
I like to think of of what I am attempting as an F7 driving a lower impedance XA25 OPS without the current sensing nor current limiting nor safety shutdown etc etc.

I appreciate your interest. It will be running fairly soon.
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